better escape code support

LANGUAGE.md

@@ -16,8 +16,9 @@ roadmap and milestone history.
 - file-local relative imports, import aliases, and qualified member access
 - transparent declaration aliases with `Name :: alias package.Member`; functions/type factories,
   named types, and globals retain their original declaration or storage identity
-- `hide` makes any named top-level declaration package-local; declarations are public by default,
-  leading underscores are ordinary identifier characters, and imports are always file-local
+- bare `@hide` and explicit `@hide:package` make a named top-level declaration package-local;
+  `@hide:file` makes it file-local, and any qualifier may precede its declaration on a separate
+  line; the qualifier words remain valid identifiers, declarations are public by default, and imports are always file-local
 - relative `.h` imports as synthetic C header package namespaces
 - native `name test { ... }` declarations with fallible-void results inferred from `testing.Error`
   and errors propagated by `try`, plus anonymous
@@ -36,15 +37,16 @@ roadmap and milestone history.
 - pointer-to-array `.len`, indexing, slicing, `.ptr` on slices and pointers-to-arrays, implicit address-taking for array-variable slices, and pointer/slice sentinel weakening
 - `ptrcast!(T, ptr)` as a first-pass pointer-child retype that preserves optionality, pointer kind, mutability, and sentinel shape
 - unsafe `constcast!(value)` for restoring mutability to pointers, optional pointers, and slices without changing their child type or shape
-- UTF-8 string literals as immutable pointers to static zero-terminated byte arrays, plus raw backtick multiline strings
+- UTF-8 string literals as immutable pointers to static zero-terminated byte arrays, supporting `\\`, `\"`, `\n`, `\r`, `\t`, `\0`, and `\xNN` escapes, plus raw backtick multiline strings
 - narrow immutable zero-terminated byte pointer/slice conversion to `*c_char` / `?*c_char` without general `u8`/`c_char` interchange
-- optionals with `null`, `orelse`, postfix `?`, conditional unwraps, guarded unwraps, and left-to-right short-circuiting multi-unwraps
+- optionals with `null`, `orelse`, postfix `?`, conditional `if`/`while` unwraps, guarded unwraps, and left-to-right short-circuiting multi-unwraps
 - nominal distinct types with explicit scalar backing conversion during construction and explicit scalar backing extraction, native enums with optional explicit integer backing and explicit backing-to-scalar casts, contextual enum literals, and imported C enums as target-backed integer aliases
-- source-order native structs, opaque nominal records with `Name :: opaque`, complete `c_struct { ... }`, keyed record literals, native untagged unions, and native tagged unions `union(Enum)` / `union(enum)`
+- compiler-reordered native structs with fields laid out by decreasing alignment (declaration order breaks ties and remains the reflection/diagnostic order), opaque nominal records with `Name :: opaque`, complete source-order `c_struct { ... }`, keyed record literals, native untagged unions, and native tagged unions `union(Enum)` / `union(enum)`
 - named native struct fields may declare defaults with `field T = expression`; keyed literals use defaults for omitted fields and explicit initializers override them
 - void-payload tagged-union variants, anonymous struct payloads, contextual `.variant`, `.variant{payload}`, and `.variant{field = value}` construction
 - native sum composition with `A | B` for unbacked enums and tagged unions, optionally grouped as `(A | B)`, using program-global `u16` variant ids
-- fallible channel types `T ! E`, where `E` is a native enum/tagged union or supported sum composition; `void ! E` functions complete successfully on fallthrough, and void-success `catch` handlers may fall through without `yield`
+- fallible channel types `T ! E`, where `E` is a native enum, native struct, tagged union, or supported sum composition; `void ! E` functions complete successfully on fallthrough, and void-success `catch` handlers may fall through without `yield`
+- bodyful local functions and root `main` may write `T!` to infer a specialization-local error channel from propagated `try` expressions and concretely typed error returns; inference composes only existing named error types, never synthesizes variants, and requires at least one inferred error
 
 #### distinct types
 
@@ -61,8 +63,9 @@ nominal result type: checked integer `+`, `-`, `*`, unary `-`, bitwise operators
 comparisons, and compound assignments; float arithmetic, unary `-`, comparisons, and compound
 assignments; and boolean equality/inequality. Integer literals and float literals are contextual.
 Typed backing values and separate distinct identities remain incompatible in ordinary operations;
-an explicit constructor is required to cross that boundary. Distinct integers also work as indices and slice bounds;
-`minval!` / `maxval!` return the distinct type. Runtime and comptime behavior match.
+an explicit constructor is required to cross that boundary. Distinct integers require an explicit
+`usize` cast for indices and slice bounds; `minval!` / `maxval!` return the distinct type.
+Runtime and comptime behavior match.
 
 `typeinfo!(Distinct).backing` reports the immediate declared backing. Standard formatting peels
 distinct layers recursively, so all scalar format verbs behave like the final scalar backing.
@@ -115,9 +118,9 @@ fields. `_` is not a keyword member name.
 - checked integer `+ - *`, unary `-`, float-only `/`, IEEE float arithmetic, comparisons, `!`, `and`, and `or`
 - Zig-style integer bitwise complement `~`, binary `&`, `|`, `xor`, shifts `<<` / `>>`, and saturating left shift `<<|`; postfix `^` remains pointer dereference
 - assignments and compound assignments `+= -= *= /= &= |= xor= <<= >>= <<|=` with single evaluation of complex lvalues; `/=` is float-only and `xor=` is contiguous
-- field access through struct values and pointers, index/slice bounds contextually coerced to `usize`, and unsigned narrower index support
+- field access through struct values and pointers, exact `usize` indices and slice bounds, and contextual integer constants in those positions
 - boolean `if` / `else if` / `else` and `for` loops with braceless single-statement bodies when the preceding expression is parenthesized or a function call
-- `while` loops with optional post-iteration update clauses
+- `while` loops with conditional unwrap captures and guards plus optional post-iteration update clauses
 - `for` loops over ranges, arrays, slices, and pointers-to-arrays with copy captures, pointer captures `|@item|`, and optional `usize` index captures; `inline for` specializes a comptime aggregate into one checked body per element
 - `break`, `continue`, labeled `break :label`, labeled `continue :label`, and labeled plain blocks; `break :label` can cross nested scopes to exit a labeled block
 - bare block scopes, `defer`, and fallible-function `errdefer` with optional error capture; cleanup is block-scoped and LIFO
@@ -152,9 +155,9 @@ and
 or
 ```
 
-Each level is left-associative. Because `|` also delimits `if` and `for` captures, a bitwise-OR
-header expression must be parenthesized before a capture list, for example
-`if (flags | mask) |value| { ... }`.
+Each level is left-associative. Because `|` also delimits `if`, `while`, and `for` captures, a
+bitwise-OR header expression must be parenthesized before a capture list, for example
+`while (flags | mask) |value| { ... }`.
 
 #### division
 
@@ -263,7 +266,7 @@ exactly once. Bare functions named `memcopy` or `memset` remain ordinary user fu
 - `std/arraylist` generic `ArrayList(T)` with direct `items` slice access, explicit capacity, allocator ownership, fallible reserve/append, clear, and deinit
 - `std/meta` reflection records plus `EnumFieldStruct(E, Field, default ?Field)`, implemented with `struct_type!`; it produces a record with one field per native enum member in declaration order, where outer `null` means no field default
 - `std/io` explicit `Io` capabilities, provider-bound `Reader`/`Writer` handles, existing-file open/close operations, allocation-free `write_all`, and comptime-expanded writer-first `print`; formatting supports natural `{}`, byte `{s}`, decimal `{d}`, integer `{b}` / `{o}` / `{x}` / `{X}`, byte-character `{c}`, scientific float `{e}`, recursively scalar-backed distinct values, and `{{` / `}}`, with malformed formats and incompatible tuple fields rejected at comptime
-- entry points are either `main func() ...` or `main func(init process.Init) ...`; `std/process.Init` carries startup capabilities, currently only `io`, while the system provider remains hidden inside `std/io`
+- entry points are either `main func() ...` or `main func(init process.Init) ...`; their success channel is `void`, `i32`, or `int` and may have an error channel; an unhandled entry error exits with status 1. `std/process.Init` carries startup capabilities, currently only `io`, while the system provider remains hidden inside `std/io`
 - `std/debug.print` is an allocation-free, failure-ignoring stderr escape hatch independent of `process.Init`
 - `std/testing` supplies fallible `expect`, expected-first `expect_equal`, and exact compile-time `expect_type`; direct calls through
   an alias of exactly `@std/testing` receive compiler-injected source locations

README.md

@@ -208,14 +208,18 @@ mem :: import "@std/mem"
 value :: math.sum(other_math.value, 1)
 ```
 
-Top-level declarations are public by default. Prefix a declaration with `hide`
-to keep it local to its package; sibling files can use it, but importing packages
-cannot. Leading underscores have no visibility meaning. Imports are always file-local
-and cannot be hidden or re-exported:
+Top-level declarations are public by default. Prefix a declaration with bare `@hide`
+to make it package-local, or spell the scope explicitly with `@hide:package` or
+`@hide:file`. The qualifier is contextual, so `hide`, `package`, and `file` remain
+available as identifiers. Imports are always file-local and cannot use visibility
+qualifiers or be re-exported:
 
 ```bro
-hide helper func() i32 { return 42 }
-hide State :: struct { value i32 }
+@hide
+shared_helper func() i32 { return 42 }
+
+@hide:file
+implementation_detail func() i32 { return shared_helper() }
 ```
 
 Current prototype features:
@@ -230,7 +234,7 @@ Current prototype features:
 - Pointer-preserving `.ptr`/`.len`, pointer-to-array indexing and slicing, postfix pointer dereference and optional unwrap, and keyed struct literals
 - Contextual integer constants and typed compile-time evaluation of arithmetic and Zig-style bitwise expressions
 - Integer `~`, `&`, `|`, `xor`, guarded `<<` / `>>`, saturating `<<|`, and their compound assignments; postfix `^` remains pointer dereference
-- Scalar-backed nominal `distinct` types with same-identity runtime/comptime operators, explicit backing extraction casts, integer bounds/indexing, reflection, and recursive standard formatting
+- Scalar-backed nominal `distinct` types with same-identity runtime/comptime operators, explicit backing extraction casts, integer bounds, reflection, and recursive standard formatting
 - Directory packages with merged declarations and file-local relative imports
 - Relative C header imports as synthetic package namespaces
 - Plain imported C structs/unions, fixed arrays, and C function pointer typedefs, including keyed literals, field access, callbacks, and Apple Silicon by-value ABI lowering

compiler/ast/ast.odin

@@ -202,13 +202,12 @@ Stmt :: struct {
 	assignment_op: Assignment_Op,
 	target:     Expr_Id,
 	expr:       Expr_Id,
-	// `If` statements use `expr` as the condition, `captures` as optional
-	// unwrap binding names, `guard` as the optional post-unwrap boolean
-	// condition, `body` as the then-block, and `else_body` as the else-block.
-	// An `else if` chain is represented as an `else_body` holding a single
-	// nested `If` statement.
-	// `While` statements use `expr` as the condition, `body` as the loop body,
-	// and `update` as the optional post-iteration statement.
+	// `If` and `While` statements use `expr` as the condition, `captures` as
+	// optional unwrap binding names, and `guard` as the optional post-unwrap
+	// boolean condition. `If` uses `body` as the then-block and `else_body` as
+	// the else-block; an `else if` chain is represented as an `else_body`
+	// holding a single nested `If` statement. `While` uses `body` as the loop
+	// body and `update` as the optional post-iteration statement.
 	// `For` statements use `expr` as the iterable, `name` as the item capture,
 	// `index_name` as the optional index capture, and `pointer_capture` to
 	// distinguish `|@item|` from copy capture.
@@ -243,12 +242,13 @@ Function :: struct {
 	generated:  bool,
 	analysis_root: bool,
 	test:       bool,
-	package_hidden: bool,
+	visibility: types.Visibility,
 	has_body:   bool,
 	variadic:   bool,
 	params:     []Param,
 	result:     Type_Syntax,
 	error:      Type_Syntax,
+	infer_error: bool,
 	body:       []Stmt_Id,
 	link_name:  string,
 	unsupported_reason: string,
@@ -265,7 +265,7 @@ Global :: struct {
 	immutable:  bool,
 	external:   bool,
 	writable:   bool,
-	package_hidden: bool,
+	visibility: types.Visibility,
 	expr:       Expr_Id,
 	diagnostic: source.Diagnostic_Id,
 }
@@ -313,7 +313,7 @@ Declaration_Alias :: struct {
 	target_pkg:  Package_Id,
 	target:      u32,
 	kind:        Declaration_Alias_Kind,
-	package_hidden: bool,
+	visibility:   types.Visibility,
 	valid:       bool,
 	diagnostic:  source.Diagnostic_Id,
 }

compiler/checker/comptime.odin

@@ -291,6 +291,7 @@ Ct_Binding :: struct {
 	value:   Ct_Value_Id,
 	cell:    Ct_Cell_Id,
 	mutable: bool,
+	open_integer: bool,
 }
 
 Ct_Error_Refinement :: struct {
@@ -473,9 +474,23 @@ ct_extend_place :: proc(
 	return ct_add_place(state, base.cell, value_type, writable, extended[:])
 }
 
-ct_bind_value :: proc(state: ^Ct_State, name: symbol.Id, value_type: types.Type, value: Ct_Value_Id, mutable: bool) {
+ct_bind_value :: proc(
+	state: ^Ct_State,
+	name: symbol.Id,
+	value_type: types.Type,
+	value: Ct_Value_Id,
+	mutable: bool,
+	open_integer := false,
+) {
 	cell := ct_add_cell(state, value, mutable)
-	append(&state.bindings, Ct_Binding{name=name, type=value_type, value=value, cell=cell, mutable=mutable})
+	append(&state.bindings, Ct_Binding{
+		name=name,
+		type=value_type,
+		value=value,
+		cell=cell,
+		mutable=mutable,
+		open_integer=open_integer,
+	})
 }
 
 ct_pop_bindings :: proc(state: ^Ct_State, start: int) {
@@ -581,6 +596,32 @@ ct_binding_value :: proc(state: ^Ct_State, index: int) -> Ct_Value_Id {
 	return binding.value
 }
 
+ct_contextualize_open_integer_binding :: proc(state: ^Ct_State, index: int, expected: types.Type) {
+	if expected != types.USIZE || index < 0 || index >= len(state.bindings) ||
+	   !state.bindings[index].open_integer {
+		return
+	}
+	value_id := ct_binding_value(state, index)
+	if value_id == INVALID_CT_VALUE || int(value_id) >= len(state.values) {
+		return
+	}
+	value := state.values[value_id]
+	if value.kind != .Integer ||
+	   !fits_integer_type(value.integer, expected, state.checker.target) {
+		return
+	}
+	value.type = expected
+	contextual := ct_add_value(state, value)
+	binding := &state.bindings[index]
+	binding.type = expected
+	binding.value = contextual
+	binding.open_integer = false
+	if binding.cell != INVALID_CT_CELL && int(binding.cell) < len(state.cells) &&
+	   state.cells[binding.cell].live {
+		state.cells[binding.cell].value = contextual
+	}
+}
+
 ct_binding_place :: proc(state: ^Ct_State, index: int) -> Ct_Place_Id {
 	if index < 0 || index >= len(state.bindings) {
 		return INVALID_CT_PLACE
@@ -1315,6 +1356,7 @@ ct_eval_expr :: proc(
 	case .Name:
 		if !symbol.is_valid(expr.qualifier) {
 			if index, ok := ct_find_binding_index(state, expr.name); ok {
+				ct_contextualize_open_integer_binding(state, index, expected)
 				return ct_observe_value(state, ct_binding_value(state, index), expr.span)
 			}
 			if value, ok := current_comptime_value(checker, expr.name); ok {
@@ -1452,16 +1494,19 @@ ct_eval_expr :: proc(
 		}
 		return ct_eval_field_value(state, base_id, expr.name, expr.span)
 	case .Index:
-		index_id, index_flow, index_ok := ct_eval_expr(state, expr.right, types.INVALID, depth+1)
+		index_id, index_flow, index_ok := ct_eval_expr(state, expr.right, types.USIZE, depth+1)
 		if !index_ok || index_flow.kind != .Normal {
 			return INVALID_CT_VALUE, index_flow, index_ok
 		}
 		index_type := state.values[index_id].type
-		index_representation := types.runtime_representation(index_type, store)
-		index_literal := is_numeric_constant_expr(checker, expr.right)
-		if !types.is_concrete_integer(index_representation) ||
-		   !index_literal && !can_implicitly_convert_type(checker, index_representation, types.USIZE) {
-			return INVALID_CT_VALUE, ct_flow(.Normal), ct_fail(state, .Not_Comptime, expr.span, "comptime index must be coercible to usize")
+		if !types.equal(index_type, types.USIZE) {
+			return INVALID_CT_VALUE, ct_flow(.Normal), ct_failf(
+				state,
+				.Not_Comptime,
+				checker.ast_module.exprs[expr.right].span,
+				"index must have type usize, got %s",
+				type_label(checker, index_type),
+			)
 		}
 		index_value, index_is_int := ct_integer_value(state, index_id)
 		if !index_is_int || index_value < 0 || index_value > i128(0x7fff_ffff) {
@@ -1962,16 +2007,19 @@ ct_eval_slice_expr :: proc(state: ^Ct_State, expr: ast.Expr, depth: int) -> (Ct_
 		if bound == ast.INVALID_EXPR {
 			continue
 		}
-		value, bound_flow, bound_ok := ct_eval_expr(state, bound, types.INVALID, depth+1)
+		value, bound_flow, bound_ok := ct_eval_expr(state, bound, types.USIZE, depth+1)
 		if !bound_ok || bound_flow.kind != .Normal {
 			return INVALID_CT_VALUE, bound_flow, bound_ok
 		}
 		bound_type := state.values[value].type
-		bound_representation := types.runtime_representation(bound_type, store)
-		bound_literal := is_numeric_constant_expr(checker, bound)
-		if !types.is_concrete_integer(bound_representation) ||
-		   !bound_literal && !can_implicitly_convert_type(checker, bound_representation, types.USIZE) {
-			return INVALID_CT_VALUE, ct_flow(.Normal), ct_fail(state, .Not_Comptime, expr.span, "slice bounds must be coercible to usize")
+		if !types.equal(bound_type, types.USIZE) {
+			return INVALID_CT_VALUE, ct_flow(.Normal), ct_failf(
+				state,
+				.Not_Comptime,
+				checker.ast_module.exprs[bound].span,
+				"slice bound must have type usize, got %s",
+				type_label(checker, bound_type),
+			)
 		}
 		integer, integer_ok := ct_integer_value(state, value)
 		if !integer_ok || integer < 0 || integer > i128(0x7fff_ffff) {
@@ -2352,6 +2400,16 @@ ct_eval_place :: proc(
 		if !index_ok || index_flow.kind != .Normal {
 			return INVALID_CT_PLACE, types.INVALID, false, index_flow, index_ok
 		}
+		index_type := state.values[index_value].type
+		if !types.equal(index_type, types.USIZE) {
+			return INVALID_CT_PLACE, types.INVALID, false, ct_flow(.Normal), ct_failf(
+				state,
+				.Not_Comptime,
+				checker.ast_module.exprs[expr.right].span,
+				"index must have type usize, got %s",
+				type_label(checker, index_type),
+			)
+		}
 		index_int, int_ok := ct_integer_value(state, index_value)
 		if !int_ok || index_int < 0 || index_int > i128(0x7fff_ffff) {
 			return INVALID_CT_PLACE, types.INVALID, false, ct_flow(.Normal), ct_fail(state, .Not_Comptime, expr.span, "comptime index must be a non-negative integer")
@@ -4487,6 +4545,19 @@ ct_return_value :: proc(state: ^Ct_State, expr_id: ast.Expr_Id, span: source.Spa
 		if expr.kind == .Enum_Literal && types.sum_has_name(&checker.module.types, error_type, u32(expr.name)) {
 			error_path = true
 			expected = error_type
+		} else if expr.kind == .Struct_Literal {
+			target_pkg, available := expr_package(checker, expr, state.pkg, state.file, true)
+			named := types.find_named(
+				&checker.module.types,
+				u32(target_pkg),
+				u32(expr.name),
+				file=u32(expr_lookup_file(expr, state.file)),
+			) if available else types.INVALID
+			named = types.resolve_alias(named, &checker.module.types)
+			if can_implicitly_convert_type(checker, named, error_type) {
+				error_path = true
+				expected = error_type
+			}
 		} else if expr.kind == .Name && !symbol.is_valid(expr.qualifier) {
 			if index, found := ct_find_binding_index(state, expr.name); found {
 				actual := state.bindings[index].type
@@ -4970,6 +5041,11 @@ ct_exec_statements :: proc(
 			} else {
 				declared := type_from_syntax(checker, statement.type, state.pkg, state.file, active_state=state)
 				expected := declared if types.is_valid(declared) && !types.is_void(declared) else types.INVALID
+				open_integer := false
+				if !is_runtime_type(checker, declared) {
+					constant := eval_integer_constant_in_context(checker, statement.expr, state.pkg, state.file)
+					open_integer = constant.kind == .Value
+				}
 				value, expr_flow, expr_ok := ct_eval_expr(state, statement.expr, expected, depth+1)
 				ok = expr_ok
 				flow = expr_flow
@@ -4978,7 +5054,14 @@ ct_exec_statements :: proc(
 						value, ok = ct_coerce_value(state, value, expected, statement.span)
 					}
 					if ok && statement.name != checker.sink_symbol {
-						ct_bind_value(state, statement.name, state.values[value].type, value, !statement.immutable)
+						ct_bind_value(
+							state,
+							statement.name,
+							state.values[value].type,
+							value,
+							!statement.immutable,
+							open_integer=open_integer,
+						)
 					}
 				}
 			}
@@ -5245,6 +5328,70 @@ ct_exec_assignment :: proc(state: ^Ct_State, statement: ast.Stmt, depth: int) ->
 	return ct_flow(.Normal), true
 }
 
+ct_eval_conditional_unwrap :: proc(
+	state: ^Ct_State,
+	statement: ast.Stmt,
+	keyword: string,
+	depth: int,
+) -> (matched: bool, scope_start: int, flow: Ct_Flow, ok: bool) {
+	checker := state.checker
+	operands: [dynamic]ast.Expr_Id
+	operands.allocator = checker.allocator
+	defer delete(operands)
+	flatten_conditional_unwrap_operands(checker.ast_module, statement.expr, &operands)
+	if len(operands) != len(statement.captures) {
+		return false, len(state.bindings), ct_flow(.Normal), ct_failf(
+			state, .Not_Comptime, statement.span,
+			"'%s' unwrap capture count mismatch",
+			keyword,
+		)
+	}
+	scope_start = len(state.bindings)
+	matched = true
+	for operand, index in operands {
+		value, operand_flow, operand_ok := ct_eval_expr(state, operand, types.INVALID, depth+1)
+		if !operand_ok || operand_flow.kind != .Normal {
+			ct_pop_bindings(state, scope_start)
+			return false, scope_start, operand_flow, operand_ok
+		}
+		v := state.values[value]
+		if v.kind == .Null {
+			matched = false
+			break
+		}
+		if v.kind != .Optional_Some {
+			ct_pop_bindings(state, scope_start)
+			return false, scope_start, ct_flow(.Normal), ct_failf(
+				state, .Not_Comptime, statement.span,
+				"'%s' unwrap requires an optional value",
+				keyword,
+			)
+		}
+		children := ct_child_slice(state, v)
+		if len(children) > 0 && statement.captures[index] != checker.sink_symbol {
+			ct_bind_value(state, statement.captures[index], state.values[children[0]].type, children[0], false)
+		}
+	}
+	if matched && statement.guard != ast.INVALID_EXPR {
+		guard, guard_flow, guard_ok := ct_eval_expr(state, statement.guard, types.BOOL, depth+1)
+		if !guard_ok || guard_flow.kind != .Normal {
+			ct_pop_bindings(state, scope_start)
+			return false, scope_start, guard_flow, guard_ok
+		}
+		guard_value, bool_ok := ct_bool_value(state, guard)
+		if !bool_ok {
+			ct_pop_bindings(state, scope_start)
+			return false, scope_start, ct_flow(.Normal), ct_failf(
+				state, .Not_Comptime, statement.span,
+				"'%s' unwrap guard must be a bool",
+				keyword,
+			)
+		}
+		matched = guard_value
+	}
+	return matched, scope_start, ct_flow(.Normal), true
+}
+
 ct_exec_if :: proc(state: ^Ct_State, statement: ast.Stmt, yield_returns: bool, depth: int) -> (Ct_Flow, bool) {
 	checker := state.checker
 	if yield_returns && statement.else_body == nil {
@@ -5271,47 +5418,9 @@ ct_exec_if :: proc(state: ^Ct_State, statement: ast.Stmt, yield_returns: bool, d
 		}
 		return ct_exec_statements(state, body, false, depth+1)
 	}
-	operands: [dynamic]ast.Expr_Id
-	operands.allocator = checker.allocator
-	defer delete(operands)
-	flatten_conditional_unwrap_operands(checker.ast_module, statement.expr, &operands)
-	if len(operands) != len(statement.captures) {
-		return ct_flow(.Normal), ct_fail(state, .Not_Comptime, statement.span, "'if' unwrap capture count mismatch")
-	}
-	scope_start := len(state.bindings)
-	matched := true
-	for operand, index in operands {
-		value, flow, ok := ct_eval_expr(state, operand, types.INVALID, depth+1)
-		if !ok || flow.kind != .Normal {
-			ct_pop_bindings(state, scope_start)
-			return flow, ok
-		}
-		v := state.values[value]
-		if v.kind == .Null {
-			matched = false
-			break
-		}
-		if v.kind != .Optional_Some {
-			ct_pop_bindings(state, scope_start)
-			return ct_flow(.Normal), ct_fail(state, .Not_Comptime, statement.span, "'if' unwrap requires an optional value")
-		}
-		children := ct_child_slice(state, v)
-		if len(children) > 0 && statement.captures[index] != checker.sink_symbol {
-			ct_bind_value(state, statement.captures[index], state.values[children[0]].type, children[0], false)
-		}
-	}
-	if matched && statement.guard != ast.INVALID_EXPR {
-		guard, flow, ok := ct_eval_expr(state, statement.guard, types.BOOL, depth+1)
-		if !ok || flow.kind != .Normal {
-			ct_pop_bindings(state, scope_start)
-			return flow, ok
-		}
-		guard_value, guard_ok := ct_bool_value(state, guard)
-		if !guard_ok {
-			ct_pop_bindings(state, scope_start)
-			return ct_flow(.Normal), ct_fail(state, .Not_Comptime, statement.span, "'if' unwrap guard must be a bool")
-		}
-		matched = guard_value
+	matched, scope_start, unwrap_flow, unwrap_ok := ct_eval_conditional_unwrap(state, statement, "if", depth)
+	if !unwrap_ok || unwrap_flow.kind != .Normal {
+		return unwrap_flow, unwrap_ok
 	}
 	body := statement.body if matched else statement.else_body
 	flow := ct_flow(.Normal)
@@ -5344,34 +5453,53 @@ ct_exec_while :: proc(state: ^Ct_State, statement: ast.Stmt, yield_returns: bool
 		if !ct_step(state, statement.span) {
 			return ct_flow(.Normal), false
 		}
-		condition, flow, ok := ct_eval_expr(state, statement.expr, types.BOOL, depth+1)
-		if !ok || flow.kind != .Normal {
-			return flow, ok
-		}
-		value, bool_ok := ct_bool_value(state, condition)
-		if !bool_ok {
-			return ct_flow(.Normal), ct_fail(state, .Not_Comptime, statement.span, "'while' condition must be a bool")
-		}
-		if !value {
-			return ct_flow(.Normal), true
+		scope_start := len(state.bindings)
+		if len(statement.captures) > 0 {
+			matched, unwrap_scope_start, flow, ok :=
+				ct_eval_conditional_unwrap(state, statement, "while", depth)
+			scope_start = unwrap_scope_start
+			if !ok || flow.kind != .Normal {
+				return flow, ok
+			}
+			if !matched {
+				ct_pop_bindings(state, scope_start)
+				return ct_flow(.Normal), true
+			}
+		} else {
+			condition, flow, ok := ct_eval_expr(state, statement.expr, types.BOOL, depth+1)
+			if !ok || flow.kind != .Normal {
+				return flow, ok
+			}
+			value, bool_ok := ct_bool_value(state, condition)
+			if !bool_ok {
+				return ct_flow(.Normal), ct_fail(state, .Not_Comptime, statement.span, "'while' condition must be a bool")
+			}
+			if !value {
+				return ct_flow(.Normal), true
+			}
 		}
 		body_flow, body_ok := ct_exec_statements(state, statement.body, yield_returns, depth+1)
 		if !body_ok {
+			ct_pop_bindings(state, scope_start)
 			return body_flow, false
 		}
 		if ct_loop_consumes_flow(body_flow, statement.label, false) {
+			ct_pop_bindings(state, scope_start)
 			return ct_flow(.Normal), true
 		}
 		if body_flow.kind != .Normal && !ct_loop_consumes_flow(body_flow, statement.label, true) {
+			ct_pop_bindings(state, scope_start)
 			return body_flow, true
 		}
 		if statement.update != ast.INVALID_STMT {
 			update := [1]ast.Stmt_Id{statement.update}
 			update_flow, update_ok := ct_exec_statements(state, update[:], false, depth+1)
 			if !update_ok || update_flow.kind != .Normal {
+				ct_pop_bindings(state, scope_start)
 				return update_flow, update_ok
 			}
 		}
+		ct_pop_bindings(state, scope_start)
 	}
 }
 

compiler/hir/hir.odin

@@ -229,12 +229,12 @@ Stmt :: struct {
 	// by computing the target address once, loading its current value, applying
 	// the operation to `expr`, and storing through the original address.
 	assignment_op: Assignment_Op,
-	// Boolean `If` statements use `expr` as the condition. Conditional unwraps
-	// use `unwraps` for the ordered optional expressions and capture locals, and
-	// `guard` for the optional boolean checked after every unwrap succeeds.
-	// Both forms use `then_body`/`else_body` as the branch statement lists.
-	// `While` statements use `expr` as the condition, `then_body` as the loop
-	// body, and `update` as the optional post-iteration statement.
+	// Boolean `If` and `While` statements use `expr` as the condition.
+	// Conditional unwraps use `unwraps` for the ordered optional expressions
+	// and capture locals, and `guard` for the optional boolean checked after
+	// every unwrap succeeds. `If` uses `then_body`/`else_body` as its branches.
+	// `While` uses `then_body` as its loop body and `update` as the optional
+	// post-iteration statement.
 	// `For` statements use `expr` as the iterable, `local` as the item capture,
 	// `index_local` as the optional sequence index, and `iterator_type` as the
 	// normalized many-item pointer type for sequence iteration.

compiler/lexer/lexer.odin

@@ -8,6 +8,10 @@ is_identifier_start :: proc(value: byte) -> bool {
 	return value == '_' || value >= 'a' && value <= 'z' || value >= 'A' && value <= 'Z'
 }
 
+is_hex_digit :: proc(value: byte) -> bool {
+	return value >= '0' && value <= '9' || value >= 'a' && value <= 'f' || value >= 'A' && value <= 'F'
+}
+
 is_identifier_continue :: proc(value: byte) -> bool {
 	return is_identifier_start(value) || value >= '0' && value <= '9'
 }
@@ -26,7 +30,6 @@ keyword_kind :: proc(text: string) -> token.Kind {
 	case "distinct":      return .Keyword_Distinct
 	case "alias":         return .Keyword_Alias
 	case "import":        return .Keyword_Import
-	case "hide":          return .Keyword_Hide
 	case "return":        return .Keyword_Return
 	case "try":           return .Keyword_Try
 	case "catch":         return .Keyword_Catch
@@ -320,13 +323,21 @@ lex :: proc(
 			for cursor < len(bytes) && bytes[cursor] != '"' && bytes[cursor] != '\n' {
 				if bytes[cursor] == '\\' {
 					cursor += 1
-					if cursor >= len(bytes) ||
-					   (bytes[cursor] != '\\' && bytes[cursor] != '"' && bytes[cursor] != 'n' &&
-					    bytes[cursor] != 'r' && bytes[cursor] != 't' && bytes[cursor] != '0') {
+					valid_escape := cursor < len(bytes) &&
+						(bytes[cursor] == '\\' || bytes[cursor] == '"' || bytes[cursor] == 'n' ||
+						 bytes[cursor] == 'r' || bytes[cursor] == 't' || bytes[cursor] == '0')
+					if cursor < len(bytes) && bytes[cursor] == 'x' {
+						valid_escape = cursor+2 < len(bytes) &&
+							is_hex_digit(bytes[cursor+1]) && is_hex_digit(bytes[cursor+2])
+						if valid_escape {
+							cursor += 2
+						}
+					}
+					if !valid_escape {
 						source.add(
 							diagnostics,
-							source.Span{file=source_file.id, start=source.Offset(max(cursor-1, start)), end=source.Offset(min(cursor+1, len(bytes)))},
-							"strings only support '\\\\', '\\\"', '\\n', '\\r', '\\t', and '\\0' escapes",
+							source.Span{file=source_file.id, start=source.Offset(max(cursor-1, start)), end=source.Offset(min(cursor+3, len(bytes)))},
+							"strings only support '\\\\', '\\\"', '\\n', '\\r', '\\t', '\\0', and '\\xNN' escapes",
 						)
 						valid = false
 					}

compiler/llvm/llvm.odin

@@ -1050,6 +1050,16 @@ emit_instruction_stream :: proc(
 						fmt.sbprintf(&emitter.builder, "  %%fallible_payload%d = getelementptr i8, ptr %%fallible_slot%d, i64 %d\n", instruction_index, instruction_index, payload_offset)
 						fmt.sbprintf(&emitter.builder, "  call void @llvm.memcpy.p0.p0.i64(ptr %%fallible_payload%d, ptr %%fallible_error_payload%d, i64 %d, i1 false)\n", instruction_index, instruction_index, error_payload_size)
 					}
+				} else if types.is_struct(error_type, &emitter.module.types) {
+					if !valid_value(instructions, instruction.args[0], error_type, &emitter.module.types) {
+						emit_recovery_value(emitter, instruction_index, instruction, "invalid fallible struct error operand")
+						continue
+					}
+					fmt.sbprintf(&emitter.builder, "  store i16 1, ptr %%fallible_slot%d\n", instruction_index)
+					fmt.sbprintf(&emitter.builder, "  %%fallible_payload%d = getelementptr i8, ptr %%fallible_slot%d, i64 %d\n", instruction_index, instruction_index, payload_offset)
+					fmt.sbprintf(&emitter.builder, "  store %s ", llvm_type(error_type, &emitter.module.types))
+					write_operand(&emitter.builder, instructions, instruction.args[0], error_type, &emitter.module.types)
+					fmt.sbprintf(&emitter.builder, ", ptr %%fallible_payload%d\n", instruction_index)
 				}
 				fmt.sbprintf(&emitter.builder, "  %%v%d = load %s, ptr %%fallible_slot%d\n", instruction_index, type_name, instruction_index)
 				continue
@@ -1107,6 +1117,15 @@ emit_instruction_stream :: proc(
 				} else if item.kind == .Range && arg_index == 2 {
 					element_type = types.BOOL
 				}
+				aggregate_index := arg_index
+				if item.kind == .Struct {
+					aggregate_index = types.physical_field_index(
+						&emitter.module.types,
+						instruction.type,
+						arg_index,
+						emitter.module.target,
+					)
+				}
 				final := arg_index == total-1
 				if final {
 					fmt.sbprintf(&emitter.builder, "  %%v%d = insertvalue %s ", instruction_index, type_name)
@@ -1124,7 +1143,7 @@ emit_instruction_stream :: proc(
 				} else {
 					write_constant(&emitter.builder, i64(item.sentinel), element_type, &emitter.module.types)
 				}
-				fmt.sbprintf(&emitter.builder, ", %d\n", arg_index)
+				fmt.sbprintf(&emitter.builder, ", %d\n", aggregate_index)
 			}
 		case .Null:
 			item, ok := types.node(&emitter.module.types, instruction.type)
@@ -1324,13 +1343,19 @@ emit_instruction_stream :: proc(
 				emit_recovery_value(emitter, instruction_index, instruction, "invalid field reference")
 				continue
 			}
+			physical_index := types.physical_field_index(
+				&emitter.module.types,
+				base_type,
+				field_index,
+				emitter.module.target,
+			)
 			if types.is_union(base_type, &emitter.module.types) {
 				fmt.sbprintf(&emitter.builder, "  %%v%d = getelementptr i8, ptr %%v%d, i64 %d\n", instruction_index, instruction.a, types.union_payload_offset(base_type, &emitter.module.types, emitter.module.target))
 			} else {
 				fmt.sbprintf(
 					&emitter.builder,
 					"  %%v%d = getelementptr %s, ptr %%v%d, i32 0, i32 %d\n",
-					instruction_index, llvm_type(base_type, &emitter.module.types), instruction.a, field_index,
+					instruction_index, llvm_type(base_type, &emitter.module.types), instruction.a, physical_index,
 				)
 			}
 		case .Load:
@@ -1389,6 +1414,12 @@ emit_instruction_stream :: proc(
 				fmt.sbprintf(&emitter.builder, "  %%v%d = load %s, ptr %%fallible_error_slot%d\n", instruction_index, type_name, instruction_index)
 				continue
 			}
+			if types.is_struct(error_type, &emitter.module.types) {
+				source_offset := types.fallible_payload_offset(channel_type, &emitter.module.types, emitter.module.target)
+				fmt.sbprintf(&emitter.builder, "  %%fallible_error_source%d = getelementptr i8, ptr %%v%d, i64 %d\n", instruction_index, instruction.a, source_offset)
+				fmt.sbprintf(&emitter.builder, "  %%v%d = load %s, ptr %%fallible_error_source%d\n", instruction_index, llvm_type(error_type, &emitter.module.types), instruction_index)
+				continue
+			}
 			emit_recovery_value(emitter, instruction_index, instruction, "unsupported fallible error type")
 		case .Store:
 			if !valid_address(instructions, instruction.a, instruction.type, &emitter.module.types) ||
@@ -2577,12 +2608,30 @@ emit_types :: proc(emitter: ^Emitter) {
 			strings.write_string(&emitter.builder, " }\n")
 			continue
 		}
+		fields := types.fields_for(&emitter.module.types, id)
 		strings.write_string(&emitter.builder, "{ ")
-		for field, field_index in types.fields_for(&emitter.module.types, id) {
-			if field_index > 0 {
+		previous_index := -1
+		for physical_index in 0..<len(fields) {
+			logical_index := -1
+			for _, candidate_index in fields {
+				if previous_index >= 0 &&
+				   !types.field_layout_precedes(
+						&emitter.module.types, id, previous_index, candidate_index, emitter.module.target,
+				   ) {
+					continue
+				}
+				if logical_index < 0 ||
+				   types.field_layout_precedes(
+						&emitter.module.types, id, candidate_index, logical_index, emitter.module.target,
+				   ) {
+					logical_index = candidate_index
+				}
+			}
+			if physical_index > 0 {
 				strings.write_string(&emitter.builder, ", ")
 			}
-			strings.write_string(&emitter.builder, llvm_type(field.type, &emitter.module.types))
+			strings.write_string(&emitter.builder, llvm_type(fields[logical_index].type, &emitter.module.types))
+			previous_index = logical_index
 		}
 		strings.write_string(&emitter.builder, " }\n")
 	}

compiler/loader/loader.odin

@@ -1249,14 +1249,29 @@ load_package :: proc(
 	return pkg_id
 }
 
+declaration_scopes_overlap :: proc(
+	left_visibility: types.Visibility,
+	left_file: ast.File_Id,
+	right_visibility: types.Visibility,
+	right_file: ast.File_Id,
+) -> bool {
+	return left_visibility != .File || right_visibility != .File || left_file == right_file
+}
+
+declaration_visible_in_file :: proc(visibility: types.Visibility, declaration_file, file: ast.File_Id) -> bool {
+	return visibility != .File || declaration_file == file
+}
+
 declaration_conflicts :: proc(module: ^ast.Module, pkg: ast.Package_Id, file: ast.File_Id, name: symbol.Id) -> bool {
 	for function in module.functions {
-		if function.pkg == pkg && function.name == name {
+		if function.pkg == pkg && function.name == name &&
+		   declaration_visible_in_file(function.visibility, function.file, file) {
 			return true
 		}
 	}
 	for global in module.globals {
-		if global.pkg == pkg && global.name == name {
+		if global.pkg == pkg && global.name == name &&
+		   declaration_visible_in_file(global.visibility, global.file, file) {
 			return true
 		}
 	}
@@ -1327,7 +1342,9 @@ find_visible_enum_global :: proc(
 	public_only := false,
 ) -> ast.Global_Id {
 	for global, index in module.globals {
-		if global.pkg == pkg && global.name == name && (!global.package_hidden || !public_only) {
+		if global.pkg == pkg && global.name == name &&
+		   ((public_only && global.visibility == .Public) ||
+		    (!public_only && declaration_visible_in_file(global.visibility, global.file, file))) {
 			return ast.global_id(index)
 		}
 	}
@@ -1451,17 +1468,20 @@ resolve_enum_values :: proc(state: ^State) {
 
 alias_conflicts_with_declaration :: proc(module: ^ast.Module, alias: ast.Declaration_Alias) -> bool {
 	for function in module.functions {
-		if function.pkg == alias.pkg && function.name == alias.name {
+		if function.pkg == alias.pkg && function.name == alias.name &&
+		   declaration_scopes_overlap(function.visibility, function.file, alias.visibility, alias.file) {
 			return true
 		}
 	}
 	for global in module.globals {
-		if global.pkg == alias.pkg && global.name == alias.name {
+		if global.pkg == alias.pkg && global.name == alias.name &&
+		   declaration_scopes_overlap(global.visibility, global.file, alias.visibility, alias.file) {
 			return true
 		}
 	}
 	for item in module.type_store.nodes {
-		if item.declared && item.pkg == u32(alias.pkg) && item.name == u32(alias.name) {
+		if item.declared && item.pkg == u32(alias.pkg) && item.name == u32(alias.name) &&
+		   declaration_scopes_overlap(item.visibility, ast.File_Id(item.file), alias.visibility, alias.file) {
 			return true
 		}
 	}
@@ -1473,7 +1493,7 @@ direct_alias_target :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symb
 	target: u32
 	kinds := 0
 	for function, index in module.functions {
-		if function.pkg == pkg && function.name == name && !function.generated && !function.package_hidden {
+		if function.pkg == pkg && function.name == name && !function.generated && function.visibility == .Public {
 			kind = .Function
 			target = u32(ast.function_id(index))
 			kinds += 1
@@ -1481,7 +1501,7 @@ direct_alias_target :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symb
 		}
 	}
 	for global, index in module.globals {
-		if global.pkg == pkg && global.name == name && !global.package_hidden {
+		if global.pkg == pkg && global.name == name && global.visibility == .Public {
 			kind = .Global
 			target = u32(ast.global_id(index))
 			kinds += 1
@@ -1498,24 +1518,24 @@ direct_alias_target :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symb
 	return kind, target, kinds
 }
 
-hidden_alias_target_exists :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symbol.Id) -> bool {
+non_public_alias_target_exists :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symbol.Id) -> bool {
 	for function in module.functions {
-		if function.pkg == pkg && function.name == name && function.package_hidden {
+		if function.pkg == pkg && function.name == name && function.visibility != .Public {
 			return true
 		}
 	}
 	for global in module.globals {
-		if global.pkg == pkg && global.name == name && global.package_hidden {
+		if global.pkg == pkg && global.name == name && global.visibility != .Public {
 			return true
 		}
 	}
 	for item in module.type_store.nodes {
-		if item.declared && item.pkg == u32(pkg) && item.name == u32(name) && item.package_hidden {
+		if item.declared && item.pkg == u32(pkg) && item.name == u32(name) && item.visibility != .Public {
 			return true
 		}
 	}
 	for alias in module.aliases {
-		if alias.valid && alias.pkg == pkg && alias.name == name && alias.package_hidden {
+		if alias.valid && alias.pkg == pkg && alias.name == name && alias.visibility != .Public {
 			return true
 		}
 	}
@@ -1524,7 +1544,7 @@ hidden_alias_target_exists :: proc(module: ^ast.Module, pkg: ast.Package_Id, nam
 
 find_public_alias :: proc(module: ^ast.Module, pkg: ast.Package_Id, name: symbol.Id) -> int {
 	for alias, index in module.aliases {
-		if alias.valid && alias.pkg == pkg && alias.name == name && !alias.package_hidden {
+		if alias.valid && alias.pkg == pkg && alias.name == name && alias.visibility == .Public {
 			return index
 		}
 	}
@@ -1581,11 +1601,11 @@ resolve_declaration_alias :: proc(state: ^State, index: int, states: []u8) -> bo
 		return false
 	}
 
-	if hidden_alias_target_exists(state.module, alias.target_pkg, alias.member) {
+	if non_public_alias_target_exists(state.module, alias.target_pkg, alias.member) {
 		alias.diagnostic = source.addf(
 			state.diagnostics,
 			alias.span,
-			"package member '%s.%s' is package-hidden",
+			"package member '%s.%s' is not public",
 			symbol.resolve(state.symbols, alias.qualifier),
 			symbol.resolve(state.symbols, alias.member),
 		)
@@ -1611,7 +1631,8 @@ validate_declaration_aliases :: proc(state: ^State) {
 			continue
 		}
 		for previous in state.module.aliases[:index] {
-			if previous.pkg == alias.pkg && previous.name == alias.name {
+			if previous.pkg == alias.pkg && previous.name == alias.name &&
+			   declaration_scopes_overlap(previous.visibility, previous.file, alias.visibility, alias.file) {
 				alias.diagnostic = source.addf(state.diagnostics, alias.span, "duplicate declaration alias '%s'", name)
 				alias.valid = false
 				break
@@ -1661,9 +1682,9 @@ validate_declaration_aliases :: proc(state: ^State) {
 			u32(alias.pkg),
 			u32(alias.name),
 			file=u32(alias.file),
-			package_hidden=alias.package_hidden,
+			visibility=alias.visibility,
 		)
-		if !types.define_alias(&state.module.type_store, id, types.Type(alias.target), alias.package_hidden) {
+		if !types.define_alias(&state.module.type_store, id, types.Type(alias.target), alias.visibility) {
 			alias.diagnostic = source.addf(state.diagnostics, alias.span, "duplicate type declaration '%s'", symbol.resolve(state.symbols, alias.name))
 			alias.valid = false
 		}

compiler/lower/lower.odin

@@ -924,6 +924,101 @@ lower_expr :: proc(state: ^State, expr_id: hir.Expr_Id) -> ir.Instruction_Id {
 	return last
 }
 
+lower_conditional_unwrap_header :: proc(
+	state: ^State,
+	statement: hir.Stmt,
+	success_lbl, false_lbl: i64,
+) {
+	for unwrap in statement.unwraps {
+		optional := lower_expr(state, unwrap.expr)
+		present := append_instruction(state, ir.Instruction{
+			op=.Optional_Is_Some,
+			span=statement.span,
+			type=types.BOOL,
+			target=ir.INVALID_REF,
+			a=optional,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		next_lbl := fresh_label(state)
+		append_instruction(state, ir.Instruction{
+			op=.Cond_Br,
+			span=statement.span,
+			type=types.VOID,
+			a=present,
+			integer=next_lbl,
+			target=ir.Ref(u32(false_lbl)),
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		append_instruction(state, ir.Instruction{
+			op=.Label,
+			span=statement.span,
+			type=types.VOID,
+			integer=next_lbl,
+			target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		if unwrap.local != hir.INVALID_LOCAL && int(unwrap.local) < len(state.func_locals) {
+			local := state.func_locals[unwrap.local]
+			slot := append_instruction(state, ir.Instruction{
+				op=.Alloca,
+				span=statement.span,
+				type=local.type,
+				target=ir.local_ref(ir.Local_Id(unwrap.local)),
+				a=ir.INVALID_INSTRUCTION,
+				b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+			state.local_slots[unwrap.local] = slot
+			inner := append_instruction(state, ir.Instruction{
+				op=.Optional_Value,
+				span=statement.span,
+				type=local.type,
+				target=ir.INVALID_REF,
+				a=optional,
+				b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+			append_instruction(state, ir.Instruction{
+				op=.Store,
+				span=statement.span,
+				type=local.type,
+				target=ir.INVALID_REF,
+				a=slot,
+				b=inner,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		}
+	}
+	if statement.guard != hir.INVALID_EXPR {
+		guard := lower_expr(state, statement.guard)
+		append_instruction(state, ir.Instruction{
+			op=.Cond_Br,
+			span=statement.span,
+			type=types.VOID,
+			a=guard,
+			integer=success_lbl,
+			target=ir.Ref(u32(false_lbl)),
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	} else {
+		append_instruction(state, ir.Instruction{
+			op=.Br,
+			span=statement.span,
+			type=types.VOID,
+			integer=success_lbl,
+			target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	}
+}
+
 lower_statements :: proc(state: ^State, statements: []hir.Stmt_Id) {
 	hir_module := state.hir_module
 	for statement_id in statements {
@@ -1136,97 +1231,7 @@ lower_statements :: proc(state: ^State, statements: []hir.Stmt_Id) {
 			false_target := else_lbl if has_else else merge_lbl
 
 			if len(statement.unwraps) > 0 {
-				// Evaluate each optional exactly once, entering the next operand only
-				// after the previous one is present. Capture storage is initialized in
-				// these success blocks so the optional guard can use every binding.
-				for unwrap in statement.unwraps {
-					optional := lower_expr(state, unwrap.expr)
-					present := append_instruction(state, ir.Instruction{
-						op=.Optional_Is_Some,
-						span=statement.span,
-						type=types.BOOL,
-						target=ir.INVALID_REF,
-						a=optional,
-						b=ir.INVALID_INSTRUCTION,
-						diagnostic=source.INVALID_DIAGNOSTIC,
-					})
-					success_lbl := fresh_label(state)
-					append_instruction(state, ir.Instruction{
-						op=.Cond_Br,
-						span=statement.span,
-						type=types.VOID,
-						a=present,
-						integer=success_lbl,
-						target=ir.Ref(u32(false_target)),
-						b=ir.INVALID_INSTRUCTION,
-						diagnostic=source.INVALID_DIAGNOSTIC,
-					})
-					append_instruction(state, ir.Instruction{
-						op=.Label,
-						span=statement.span,
-						type=types.VOID,
-						integer=success_lbl,
-						target=ir.INVALID_REF,
-						a=ir.INVALID_INSTRUCTION,
-						b=ir.INVALID_INSTRUCTION,
-						diagnostic=source.INVALID_DIAGNOSTIC,
-					})
-					if unwrap.local != hir.INVALID_LOCAL && int(unwrap.local) < len(state.func_locals) {
-						local := state.func_locals[unwrap.local]
-						slot := append_instruction(state, ir.Instruction{
-							op=.Alloca,
-							span=statement.span,
-							type=local.type,
-							target=ir.local_ref(ir.Local_Id(unwrap.local)),
-							a=ir.INVALID_INSTRUCTION,
-							b=ir.INVALID_INSTRUCTION,
-							diagnostic=source.INVALID_DIAGNOSTIC,
-						})
-						state.local_slots[unwrap.local] = slot
-						inner := append_instruction(state, ir.Instruction{
-							op=.Optional_Value,
-							span=statement.span,
-							type=local.type,
-							target=ir.INVALID_REF,
-							a=optional,
-							b=ir.INVALID_INSTRUCTION,
-							diagnostic=source.INVALID_DIAGNOSTIC,
-						})
-						append_instruction(state, ir.Instruction{
-							op=.Store,
-							span=statement.span,
-							type=local.type,
-							target=ir.INVALID_REF,
-							a=slot,
-							b=inner,
-							diagnostic=source.INVALID_DIAGNOSTIC,
-						})
-					}
-				}
-				if statement.guard != hir.INVALID_EXPR {
-					guard := lower_expr(state, statement.guard)
-					append_instruction(state, ir.Instruction{
-						op=.Cond_Br,
-						span=statement.span,
-						type=types.VOID,
-						a=guard,
-						integer=then_lbl,
-						target=ir.Ref(u32(false_target)),
-						b=ir.INVALID_INSTRUCTION,
-						diagnostic=source.INVALID_DIAGNOSTIC,
-					})
-				} else {
-					append_instruction(state, ir.Instruction{
-						op=.Br,
-						span=statement.span,
-						type=types.VOID,
-						integer=then_lbl,
-						target=ir.INVALID_REF,
-						a=ir.INVALID_INSTRUCTION,
-						b=ir.INVALID_INSTRUCTION,
-						diagnostic=source.INVALID_DIAGNOSTIC,
-					})
-				}
+				lower_conditional_unwrap_header(state, statement, then_lbl, false_target)
 			} else {
 				cond := lower_expr(state, statement.expr)
 				append_instruction(state, ir.Instruction{
@@ -1282,12 +1287,16 @@ lower_statements :: proc(state: ^State, statements: []hir.Stmt_Id) {
 				target=ir.INVALID_REF, a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
 				diagnostic=source.INVALID_DIAGNOSTIC,
 			})
-			condition := lower_expr(state, statement.expr)
-			append_instruction(state, ir.Instruction{
-				op=.Cond_Br, span=statement.span, type=types.VOID,
-				a=condition, integer=body_lbl, target=ir.Ref(u32(exit_lbl)),
-				b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
-			})
+			if len(statement.unwraps) > 0 {
+				lower_conditional_unwrap_header(state, statement, body_lbl, exit_lbl)
+			} else {
+				condition := lower_expr(state, statement.expr)
+				append_instruction(state, ir.Instruction{
+					op=.Cond_Br, span=statement.span, type=types.VOID,
+					a=condition, integer=body_lbl, target=ir.Ref(u32(exit_lbl)),
+					b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+				})
+			}
 			append_instruction(state, ir.Instruction{
 				op=.Label, span=statement.span, type=types.VOID, integer=body_lbl,
 				target=ir.INVALID_REF, a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
@@ -1752,41 +1761,49 @@ lower_global_initializer :: proc(hir_module: ^hir.Module, global: hir.Global, al
 
 append_injected_main :: proc(module: ^ir.Module, hir_module: ^hir.Module, allocator: mem.Allocator) {
 	main_index, main_ok := hir.index(hir_module.injected_main, hir.INVALID_FUNCTION, len(hir_module.functions))
+	if !main_ok {
+		return
+	}
+	main_function := &hir_module.functions[main_index]
 	provider_index, provider_ok := hir.index(hir_module.io_provider, hir.INVALID_FUNCTION, len(hir_module.functions))
-	if !main_ok || !provider_ok {
+	param_index := -1
+	if len(main_function.params) == 1 {
+		param_index, main_ok = hir.index(main_function.params[0], hir.INVALID_LOCAL, len(main_function.locals))
+		if !main_ok || !provider_ok {
+			return
+		}
+	} else if len(main_function.params) != 0 {
 		return
 	}
 
 	instructions: [dynamic]ir.Instruction
 	instructions.allocator = allocator
-	provider_call := ir.instruction_id(len(instructions))
-	append(&instructions, ir.Instruction{
-		op=.Call,
-		type=hir_module.functions[provider_index].result,
-		target=ir.function_ref(ir.Function_Id(provider_index)),
-		a=ir.INVALID_INSTRUCTION,
-		b=ir.INVALID_INSTRUCTION,
-		diagnostic=source.INVALID_DIAGNOSTIC,
-	})
-	main_function := &hir_module.functions[main_index]
-	param_index, param_ok := hir.index(main_function.params[0], hir.INVALID_LOCAL, len(main_function.locals))
-	if !param_ok {
-		return
+	args: []ir.Instruction_Id
+	if param_index >= 0 {
+		provider_call := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Call,
+			type=hir_module.functions[provider_index].result,
+			target=ir.function_ref(ir.Function_Id(provider_index)),
+			a=ir.INVALID_INSTRUCTION,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		init_args := make([]ir.Instruction_Id, 1, allocator)
+		init_args[0] = provider_call
+		init_value := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Aggregate,
+			type=main_function.locals[param_index].type,
+			args=init_args,
+			target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		args = make([]ir.Instruction_Id, 1, allocator)
+		args[0] = init_value
 	}
-	init_args := make([]ir.Instruction_Id, 1, allocator)
-	init_args[0] = provider_call
-	init_value := ir.instruction_id(len(instructions))
-	append(&instructions, ir.Instruction{
-		op=.Aggregate,
-		type=main_function.locals[param_index].type,
-		args=init_args,
-		target=ir.INVALID_REF,
-		a=ir.INVALID_INSTRUCTION,
-		b=ir.INVALID_INSTRUCTION,
-		diagnostic=source.INVALID_DIAGNOSTIC,
-	})
-	args := make([]ir.Instruction_Id, 1, allocator)
-	args[0] = init_value
 	main_call := ir.instruction_id(len(instructions))
 	append(&instructions, ir.Instruction{
 		op=.Call,
@@ -1797,36 +1814,114 @@ append_injected_main :: proc(module: ^ir.Module, hir_module: ^hir.Module, alloca
 		b=ir.INVALID_INSTRUCTION,
 		diagnostic=source.INVALID_DIAGNOSTIC,
 	})
-	if types.is_void(hir_module.functions[main_index].result) {
+
+	if types.kind(main_function.result, &hir_module.types) == .Fallible {
+		success := types.fallible_success(main_function.result, &hir_module.types)
+		channel_slot := ir.instruction_id(len(instructions))
 		append(&instructions, ir.Instruction{
-			op=.Return_Void,
-			type=types.VOID,
-			target=ir.INVALID_REF,
-			a=ir.INVALID_INSTRUCTION,
-			b=ir.INVALID_INSTRUCTION,
+			op=.Alloca, type=main_function.result, target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
-	} else {
 		append(&instructions, ir.Instruction{
-			op=.Return,
-			type=hir_module.functions[main_index].result,
-			target=ir.INVALID_REF,
-			a=main_call,
-			b=ir.INVALID_INSTRUCTION,
+			op=.Store, type=main_function.result, target=ir.INVALID_REF,
+			a=channel_slot, b=main_call, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		code := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Union_Tag, type=types.U16, target=ir.INVALID_REF,
+			a=channel_slot, b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		zero_tag := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Const, type=types.U16, integer=0, target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
+		ok := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Compare, type=types.BOOL, integer=i64(ir.Compare_Predicate.Eq),
+			target=ir.INVALID_REF, a=code, b=zero_tag,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		append(&instructions, ir.Instruction{
+			op=.Cond_Br, type=types.VOID, integer=1, target=ir.Ref(0), a=ok,
+			b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		append(&instructions, ir.Instruction{
+			op=.Label, type=types.VOID, integer=0, target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		failure := ir.instruction_id(len(instructions))
+		append(&instructions, ir.Instruction{
+			op=.Const, type=types.I32, integer=1, target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		append(&instructions, ir.Instruction{
+			op=.Return, type=types.I32, target=ir.INVALID_REF, a=failure,
+			b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		append(&instructions, ir.Instruction{
+			op=.Label, type=types.VOID, integer=1, target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+		success_value := ir.INVALID_INSTRUCTION
+		if types.is_void(success) {
+			success_value = ir.instruction_id(len(instructions))
+			append(&instructions, ir.Instruction{
+				op=.Const, type=types.I32, integer=0, target=ir.INVALID_REF,
+				a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		} else {
+			payload := ir.instruction_id(len(instructions))
+			append(&instructions, ir.Instruction{
+				op=.Field_Address, type=success, integer=0, target=ir.INVALID_REF,
+				a=channel_slot, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+			success_value = ir.instruction_id(len(instructions))
+			append(&instructions, ir.Instruction{
+				op=.Load, type=success, target=ir.INVALID_REF, a=payload,
+				b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		}
+		append(&instructions, ir.Instruction{
+			op=.Return, type=types.I32, target=ir.INVALID_REF, a=success_value,
+			b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	} else {
+		exit_value := main_call
+		if types.is_void(main_function.result) {
+			exit_value = ir.instruction_id(len(instructions))
+			append(&instructions, ir.Instruction{
+				op=.Const, type=types.I32, integer=0, target=ir.INVALID_REF,
+				a=ir.INVALID_INSTRUCTION, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		}
+		append(&instructions, ir.Instruction{
+			op=.Return, type=types.I32, target=ir.INVALID_REF, a=exit_value,
+			b=ir.INVALID_INSTRUCTION, diagnostic=source.INVALID_DIAGNOSTIC,
+		})
 	}
 
+	problematic := main_function.problematic
+	if provider_ok {
+		problematic = problematic || hir_module.functions[provider_index].problematic
+	}
 	append(&module.functions, ir.Function{
 		link_name=fmt.aprintf("main", allocator=allocator),
 		calling_convention=.C,
 		implementation=.Definition,
 		linkage=.External,
 		is_main=true,
-		result=hir_module.functions[main_index].result,
+		result=types.I32,
 		instructions=instructions[:],
-		problematic=hir_module.functions[main_index].problematic ||
-		            hir_module.functions[provider_index].problematic,
+		problematic=problematic,
 	})
 }
 

compiler/parser/parser.odin

@@ -31,7 +31,12 @@ Parser :: struct {
 	capture_pipe: bool,
 	// A parenthesized `if` condition ends before a leading-dot brace-less body.
 	if_condition: bool,
-	hidden_names: [dynamic]symbol.Id,
+	local_names: [dynamic]Local_Name,
+}
+
+Local_Name :: struct {
+	name:       symbol.Id,
+	visibility: types.Visibility,
 }
 
 MAX_EXPRESSION_NESTING :: 256
@@ -43,16 +48,16 @@ token_text :: proc(parser: ^Parser, tok: token.Token) -> string {
 	return parser.source_file.text[int(tok.span.start):int(tok.span.end)]
 }
 
-package_hidden_name :: proc(parser: ^Parser, name: symbol.Id) -> bool {
-	for hidden in parser.hidden_names {
-		if hidden == name {
-			return true
+declaration_visibility :: proc(parser: ^Parser, name: symbol.Id) -> types.Visibility {
+	for local in parser.local_names {
+		if local.name == name {
+			return local.visibility
 		}
 	}
-	return false
+	return .Public
 }
 
-collect_hidden_names :: proc(parser: ^Parser) {
+collect_local_names :: proc(parser: ^Parser) {
 	depth := 0
 	for item, index in parser.tokens.items {
 		#partial switch item.kind {
@@ -60,10 +65,38 @@ collect_hidden_names :: proc(parser: ^Parser) {
 			depth += 1
 		case .Right_Brace:
 			depth = max(depth-1, 0)
-		case .Keyword_Hide:
-			if depth == 0 && index+1 < len(parser.tokens.items) &&
-			   parser.tokens.items[index+1].kind == .Identifier {
-				append(&parser.hidden_names, parser.tokens.items[index+1].symbol)
+		case .At:
+			if depth != 0 || index+1 >= len(parser.tokens.items) ||
+			   parser.tokens.items[index+1].kind != .Identifier ||
+			   token_text(parser, parser.tokens.items[index+1]) != "hide" {
+				continue
+			}
+			visibility := types.Visibility.Package
+			name_index := index+2
+			if name_index < len(parser.tokens.items) &&
+			   parser.tokens.items[name_index].kind == .Colon {
+				if index+3 >= len(parser.tokens.items) ||
+				   parser.tokens.items[index+3].kind != .Identifier {
+					continue
+				}
+				scope := token_text(parser, parser.tokens.items[index+3])
+				if scope == "file" {
+					visibility = .File
+				} else if scope != "package" {
+					continue
+				}
+				name_index = index+4
+			}
+			for name_index < len(parser.tokens.items) &&
+			    parser.tokens.items[name_index].kind == .Newline {
+				name_index += 1
+			}
+			if name_index < len(parser.tokens.items) &&
+			   parser.tokens.items[name_index].kind == .Identifier {
+				append(&parser.local_names, Local_Name{
+					name=parser.tokens.items[name_index].symbol,
+					visibility=visibility,
+				})
 			}
 		case:
 		}
@@ -186,6 +219,16 @@ decode_character :: proc(parser: ^Parser, tok: token.Token) -> (u64, bool) {
 	return u64(value), width == len(contents)
 }
 
+decode_hex_digit :: proc(value: byte) -> byte {
+	if value >= '0' && value <= '9' {
+		return value - '0'
+	}
+	if value >= 'a' && value <= 'f' {
+		return value - 'a' + 10
+	}
+	return value - 'A' + 10
+}
+
 parse_type_constant :: proc(parser: ^Parser) -> (u64, bool) {
 	negative := false
 	if _, ok := allow(parser, .Minus); ok {
@@ -403,8 +446,8 @@ parse_type_atom :: proc(parser: ^Parser) -> ast.Type_Syntax {
 			source.add(parser.diagnostics, current(parser).span, "expected ')' after function type parameters")
 		}
 		result := parse_type(parser)
-		if _, ok := allow(parser, .Bang); ok {
-			error_type := parse_error_type(parser)
+		error_type, _ := parse_function_error(parser, false)
+		if types.is_valid(error_type) {
 			if c_abi {
 				source.add(parser.diagnostics, current(parser).span, "c_func pointer types cannot be fallible")
 			} else {
@@ -437,7 +480,7 @@ parse_type_atom :: proc(parser: ^Parser) -> ast.Type_Syntax {
 			u32(name.symbol),
 			u32(qualifier),
 			u32(parser.file),
-			!symbol.is_valid(qualifier) && package_hidden_name(parser, name.symbol),
+			types.Visibility.Public if symbol.is_valid(qualifier) else declaration_visibility(parser, name.symbol),
 		)
 		if token_text(parser, name) == "struct_type" &&
 		   current(parser).kind == .Bang && peek(parser).kind == .Left_Paren {
@@ -530,6 +573,22 @@ parse_error_type :: proc(parser: ^Parser) -> ast.Type_Syntax {
 	return parse_type_pipe_tail(parser, left)
 }
 
+parse_function_error :: proc(parser: ^Parser, allow_inferred: bool) -> (ast.Type_Syntax, bool) {
+	bang, present := allow(parser, .Bang)
+	if !present {
+		return types.INVALID, false
+	}
+	kind := current(parser).kind
+	inferred := kind == .Left_Brace || kind == .Newline || kind == .Eof
+	if !inferred {
+		return parse_error_type(parser), false
+	}
+	if !allow_inferred {
+		source.add(parser.diagnostics, bang.span, "inferred error channels require a function body")
+	}
+	return types.INVALID, true
+}
+
 skip_parenthesized :: proc(parser: ^Parser) -> source.Span {
 	start := current(parser)
 	depth := 0
@@ -2180,19 +2239,7 @@ parse_control_body :: proc(parser: ^Parser, header: ast.Expr_Id, diagnostic: str
 	return single
 }
 
-parse_if :: proc(parser: ^Parser) -> ast.Stmt_Id {
-	start := advance(parser) // consume 'if'
-	skip_newlines(parser)
-	saved := parser.no_struct_literal
-	parser.no_struct_literal = true
-	saved_capture_pipe := parser.capture_pipe
-	saved_if_condition := parser.if_condition
-	parser.capture_pipe = true
-	parser.if_condition = true
-	condition := parse_expression(parser)
-	parser.if_condition = saved_if_condition
-	parser.capture_pipe = saved_capture_pipe
-	parser.no_struct_literal = saved
+parse_conditional_captures :: proc(parser: ^Parser) -> ([]symbol.Id, ast.Expr_Id) {
 	captures: [dynamic]symbol.Id
 	captures.allocator = parser.module.allocator
 	guard := ast.INVALID_EXPR
@@ -2218,9 +2265,9 @@ parse_if :: proc(parser: ^Parser) -> ast.Stmt_Id {
 			if current(parser).kind == .Pipe {
 				source.add(parser.diagnostics, current(parser).span, "expected a guard expression after ':'")
 			} else {
-				saved = parser.no_struct_literal
+				saved := parser.no_struct_literal
 				parser.no_struct_literal = true
-				saved_capture_pipe = parser.capture_pipe
+				saved_capture_pipe := parser.capture_pipe
 				parser.capture_pipe = true
 				guard = parse_expression(parser)
 				parser.capture_pipe = saved_capture_pipe
@@ -2231,6 +2278,23 @@ parse_if :: proc(parser: ^Parser) -> ast.Stmt_Id {
 			source.add(parser.diagnostics, current(parser).span, "expected '|' to close unwrap captures")
 		}
 	}
+	return captures[:], guard
+}
+
+parse_if :: proc(parser: ^Parser) -> ast.Stmt_Id {
+	start := advance(parser) // consume 'if'
+	skip_newlines(parser)
+	saved := parser.no_struct_literal
+	parser.no_struct_literal = true
+	saved_capture_pipe := parser.capture_pipe
+	saved_if_condition := parser.if_condition
+	parser.capture_pipe = true
+	parser.if_condition = true
+	condition := parse_expression(parser)
+	parser.if_condition = saved_if_condition
+	parser.capture_pipe = saved_capture_pipe
+	parser.no_struct_literal = saved
+	captures, guard := parse_conditional_captures(parser)
 	then_body := parse_control_body(
 		parser,
 		condition,
@@ -2559,8 +2623,12 @@ parse_while :: proc(parser: ^Parser) -> ast.Stmt_Id {
 	skip_newlines(parser)
 	saved := parser.no_struct_literal
 	parser.no_struct_literal = true
+	saved_capture_pipe := parser.capture_pipe
+	parser.capture_pipe = true
 	condition := parse_expression(parser)
+	parser.capture_pipe = saved_capture_pipe
 	parser.no_struct_literal = saved
+	captures, guard := parse_conditional_captures(parser)
 	skip_newlines(parser)
 
 	update := ast.INVALID_STMT
@@ -2582,6 +2650,8 @@ parse_while :: proc(parser: ^Parser) -> ast.Stmt_Id {
 		span=span_from(start.span, previous(parser).span),
 		expr=condition,
 		body=body,
+		captures=captures,
+		guard=guard,
 		label=label,
 		update=update,
 		diagnostic=source.INVALID_DIAGNOSTIC,
@@ -2589,7 +2659,7 @@ parse_while :: proc(parser: ^Parser) -> ast.Stmt_Id {
 	return id
 }
 
-parse_function :: proc(parser: ^Parser, name: token.Token, c_abi, package_hidden: bool) {
+parse_function :: proc(parser: ^Parser, name: token.Token, c_abi: bool, visibility: types.Visibility) {
 	advance(parser)
 	if _, ok := allow(parser, .Left_Paren); !ok {
 		source.add(parser.diagnostics, current(parser).span, "expected '(' after 'func'")
@@ -2600,10 +2670,7 @@ parse_function :: proc(parser: ^Parser, name: token.Token, c_abi, package_hidden
 	}
 	skip_newlines(parser)
 	result := parse_type(parser)
-	error_type := types.INVALID
-	if _, ok := allow(parser, .Bang); ok {
-		error_type = parse_error_type(parser)
-	}
+	error_type, infer_error := parse_function_error(parser, true)
 	end := previous(parser)
 	ended_by_newline := current(parser).kind == .Newline
 	if current(parser).kind == .Newline {
@@ -2620,12 +2687,13 @@ parse_function :: proc(parser: ^Parser, name: token.Token, c_abi, package_hidden
 			pkg=parser.pkg,
 			file=parser.file,
 			c_abi=c_abi,
-			package_hidden=package_hidden,
+			visibility=visibility,
 			has_body=false,
 			variadic=variadic,
 			params=params,
 			result=result,
 			error=error_type,
+			infer_error=infer_error,
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
 		return
@@ -2639,12 +2707,13 @@ parse_function :: proc(parser: ^Parser, name: token.Token, c_abi, package_hidden
 		pkg=parser.pkg,
 		file=parser.file,
 		c_abi=c_abi,
-		package_hidden=package_hidden,
+		visibility=visibility,
 		has_body=true,
 		variadic=variadic,
 		params=params,
 		result=result,
 		error=error_type,
+		infer_error=infer_error,
 		body=body,
 		diagnostic=source.INVALID_DIAGNOSTIC,
 	})
@@ -2661,10 +2730,7 @@ parse_function_literal :: proc(parser: ^Parser) -> ast.Expr_Id {
 	}
 	skip_newlines(parser)
 	result := parse_type(parser)
-	error_type := types.INVALID
-	if _, ok := allow(parser, .Bang); ok {
-		error_type = parse_error_type(parser)
-	}
+	error_type, infer_error := parse_function_error(parser, true)
 	if current(parser).kind == .Newline {
 		skip_newlines(parser)
 	}
@@ -2687,6 +2753,7 @@ parse_function_literal :: proc(parser: ^Parser) -> ast.Expr_Id {
 		params=params,
 		result=result,
 		error=error_type,
+		infer_error=infer_error,
 		body=body,
 		diagnostic=source.INVALID_DIAGNOSTIC,
 	})
@@ -2825,9 +2892,9 @@ parse_inline_union_type :: proc(parser: ^Parser) -> types.Type {
 	return types.union_anonymous(&parser.module.type_store, fields[:], tag)
 }
 
-parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout, package_hidden: bool, is_union := false) {
+parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout: bool, visibility: types.Visibility, is_union := false) {
 	start := advance(parser)
-	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), package_hidden=package_hidden)
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), visibility=visibility)
 	// A tagged union spells its discriminant in parens: `union(Enum)` reuses an existing
 	// enum; `union(enum)` synthesizes one from the variant names after the body is parsed.
 	tag := types.INVALID
@@ -2861,7 +2928,7 @@ parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout, package_hidde
 				"native union declarations require a body" if is_union else "native struct declarations require a body",
 			)
 		}
-		if !types.define_record(&parser.module.type_store, id, nil, c_layout, true, is_union, tag=tag, declared_tag=declared_tag, package_hidden=package_hidden) {
+		if !types.define_record(&parser.module.type_store, id, nil, c_layout, true, is_union, tag=tag, declared_tag=declared_tag, visibility=visibility) {
 			source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 		}
 		if !ended_by_newline {
@@ -2898,7 +2965,7 @@ parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout, package_hidde
 	if is_union && (inferred_tag || types.is_valid(declared_tag)) {
 		tag = synthesize_union_tag(parser, fields[:])
 	}
-	if !types.define_record(&parser.module.type_store, id, fields[:], c_layout, false, is_union, tag=tag, declared_tag=declared_tag, tuple=tuple, package_hidden=package_hidden) {
+	if !types.define_record(&parser.module.type_store, id, fields[:], c_layout, false, is_union, tag=tag, declared_tag=declared_tag, tuple=tuple, visibility=visibility) {
 		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 	} else if !c_layout && !is_union && !tuple {
 		for value, index in defaults {
@@ -2917,10 +2984,10 @@ parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout, package_hidde
 	_ = finish_statement(parser)
 }
 
-parse_opaque :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
+parse_opaque :: proc(parser: ^Parser, name: token.Token, visibility: types.Visibility) {
 	start := advance(parser)
-	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), package_hidden=package_hidden)
-	if !types.define_record(&parser.module.type_store, id, nil, false, true, false, package_hidden=package_hidden) {
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), visibility=visibility)
+	if !types.define_record(&parser.module.type_store, id, nil, false, true, false, visibility=visibility) {
 		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 	}
 	if current(parser).kind == .Left_Brace {
@@ -2945,11 +3012,11 @@ synthesize_union_tag :: proc(parser: ^Parser, fields: []types.Field) -> types.Ty
 	return types.enum_anonymous(&parser.module.type_store, members, types.U16)
 }
 
-parse_distinct :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
+parse_distinct :: proc(parser: ^Parser, name: token.Token, visibility: types.Visibility) {
 	start := advance(parser)
 	child := parse_type(parser)
-	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), package_hidden=package_hidden)
-	if !types.define_distinct(&parser.module.type_store, id, child, package_hidden) {
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), visibility=visibility)
+	if !types.define_distinct(&parser.module.type_store, id, child, visibility) {
 		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 	}
 	if !types.is_valid(child) {
@@ -2958,7 +3025,7 @@ parse_distinct :: proc(parser: ^Parser, name: token.Token, package_hidden: bool)
 	_ = finish_statement(parser)
 }
 
-parse_alias :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
+parse_alias :: proc(parser: ^Parser, name: token.Token, visibility: types.Visibility) {
 	start := advance(parser)
 	saved := parser.cursor
 	if current(parser).kind == .Identifier && peek(parser).kind == .Dot {
@@ -2975,7 +3042,7 @@ parse_alias :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
 					pkg=parser.pkg,
 					file=parser.file,
 					target_pkg=ast.INVALID_PACKAGE,
-					package_hidden=package_hidden,
+					visibility=visibility,
 					valid=true,
 					diagnostic=source.INVALID_DIAGNOSTIC,
 				})
@@ -2986,8 +3053,8 @@ parse_alias :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
 	}
 	parser.cursor = saved
 	child := parse_type(parser)
-	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), package_hidden=package_hidden)
-	if !types.define_alias(&parser.module.type_store, id, child, package_hidden) {
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), visibility=visibility)
+	if !types.define_alias(&parser.module.type_store, id, child, visibility) {
 		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 	}
 	if !types.is_valid(child) {
@@ -3130,7 +3197,7 @@ parse_inline_enum_type :: proc(parser: ^Parser) -> types.Type {
 	return types.enum_anonymous(&parser.module.type_store, members[:], backing)
 }
 
-parse_enum :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
+parse_enum :: proc(parser: ^Parser, name: token.Token, visibility: types.Visibility) {
 	start := advance(parser)
 	explicit_backing := false
 	backing := types.INVALID
@@ -3152,8 +3219,8 @@ parse_enum :: proc(parser: ^Parser, name: token.Token, package_hidden: bool) {
 		_ = finish_statement(parser)
 		return
 	}
-	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), package_hidden=package_hidden)
-	if !types.define_enum(&parser.module.type_store, id, backing, members[:], explicit_backing, package_hidden) {
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol), file=u32(parser.file), visibility=visibility)
+	if !types.define_enum(&parser.module.type_store, id, backing, members[:], explicit_backing, visibility) {
 		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
 	}
 	if explicit_backing && deferred {
@@ -3186,6 +3253,9 @@ decode_import_path :: proc(parser: ^Parser, tok: token.Token) -> string {
 			case 'r': value = '\r'
 			case 't': value = '\t'
 			case '0': value = 0
+			case 'x':
+				value = decode_hex_digit(text[index+1])*16 + decode_hex_digit(text[index+2])
+				index += 2
 			case:
 			}
 		}
@@ -3282,10 +3352,38 @@ parse_test :: proc(parser: ^Parser, name: token.Token) {
 }
 
 parse_top_level :: proc(parser: ^Parser) {
-	hide_token, package_hidden := allow(parser, .Keyword_Hide)
+	modifier := current(parser)
+	hide_name := peek(parser)
+	visibility := types.Visibility.Public
+	has_modifier := modifier.kind == .At && hide_name.kind == .Identifier &&
+	                token_text(parser, hide_name) == "hide"
+	if has_modifier {
+		visibility = .Package
+		advance(parser)
+		advance(parser)
+		if _, scoped := allow(parser, .Colon); scoped {
+			if current(parser).kind == .Identifier {
+				scope := advance(parser)
+				scope_text := token_text(parser, scope)
+				if scope_text == "file" {
+					visibility = .File
+				} else if scope_text != "package" {
+					source.addf(
+						parser.diagnostics,
+						scope.span,
+						"unknown hide scope '%s'; expected 'package' or 'file'",
+						scope_text,
+					)
+				}
+			} else {
+				source.add(parser.diagnostics, current(parser).span, "expected 'package' or 'file' after '@hide:'")
+			}
+		}
+		skip_newlines(parser)
+	}
 	if current(parser).kind == .Keyword_Test && peek(parser).kind == .Keyword_Import {
-		if package_hidden {
-			source.add(parser.diagnostics, hide_token.span, "test imports cannot use 'hide'")
+		if has_modifier {
+			source.add(parser.diagnostics, modifier.span, "test imports cannot use a visibility modifier")
 		}
 		start := advance(parser)
 		advance(parser) // consume 'import'
@@ -3293,15 +3391,15 @@ parse_top_level :: proc(parser: ^Parser) {
 		return
 	}
 	if current(parser).kind == .Keyword_Import {
-		if package_hidden {
-			source.add(parser.diagnostics, hide_token.span, "imports are already file-local and cannot use 'hide'")
+		if has_modifier {
+			source.add(parser.diagnostics, modifier.span, "imports are already file-local and cannot use a visibility modifier")
 		}
 		start := advance(parser)
 		parse_import(parser, token.Token{}, start)
 		return
 	}
 	if current(parser).kind != .Identifier {
-		message := "expected a declaration name after 'hide'" if package_hidden else "expected a top-level declaration"
+		message := "expected a declaration name after visibility modifier" if has_modifier else "expected a top-level declaration"
 		source.add(parser.diagnostics, current(parser).span, message)
 		for current(parser).kind != .Newline && current(parser).kind != .Eof {
 			advance(parser)
@@ -3311,8 +3409,8 @@ parse_top_level :: proc(parser: ^Parser) {
 	}
 	name := advance(parser)
 	if current(parser).kind == .Keyword_Test {
-		if package_hidden {
-			source.add(parser.diagnostics, hide_token.span, "test declarations cannot use 'hide'")
+		if has_modifier {
+			source.add(parser.diagnostics, modifier.span, "test declarations cannot use a visibility modifier")
 		}
 		parse_test(parser, name)
 		return
@@ -3322,8 +3420,8 @@ parse_top_level :: proc(parser: ^Parser) {
 		advance(parser)
 		skip_newlines(parser)
 		if current(parser).kind == .Keyword_Import {
-			if package_hidden {
-				source.add(parser.diagnostics, hide_token.span, "imports are already file-local and cannot use 'hide'")
+			if has_modifier {
+				source.add(parser.diagnostics, modifier.span, "imports are already file-local and cannot use a visibility modifier")
 			}
 			start := advance(parser)
 			parse_import(parser, name, start)
@@ -3333,7 +3431,7 @@ parse_top_level :: proc(parser: ^Parser) {
 	}
 	if current(parser).kind == .Keyword_Func || current(parser).kind == .Keyword_C_Func {
 		c_abi := current(parser).kind == .Keyword_C_Func
-		parse_function(parser, name, c_abi, package_hidden)
+		parse_function(parser, name, c_abi, visibility)
 		return
 	}
 	type_syntax := types.INVALID
@@ -3362,32 +3460,32 @@ parse_top_level :: proc(parser: ^Parser) {
 		source.add(parser.diagnostics, span_from(name.span, current(parser).span),
 		           "function declarations do not use '::'; write 'name func(...)' or 'name c_func(...)'")
 		c_abi := current(parser).kind == .Keyword_C_Func
-		parse_function(parser, name, c_abi, package_hidden)
+		parse_function(parser, name, c_abi, visibility)
 		return
 	}
 	if operator.kind == .Colon_Colon &&
 	   (current(parser).kind == .Keyword_Struct || current(parser).kind == .Keyword_C_Struct) {
-		parse_struct(parser, name, current(parser).kind == .Keyword_C_Struct, package_hidden)
+		parse_struct(parser, name, current(parser).kind == .Keyword_C_Struct, visibility)
 		return
 	}
 	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Opaque {
-		parse_opaque(parser, name, package_hidden)
+		parse_opaque(parser, name, visibility)
 		return
 	}
 	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Union {
-		parse_struct(parser, name, false, package_hidden, is_union=true)
+		parse_struct(parser, name, false, visibility, is_union=true)
 		return
 	}
 	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Enum {
-		parse_enum(parser, name, package_hidden)
+		parse_enum(parser, name, visibility)
 		return
 	}
 	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Distinct {
-		parse_distinct(parser, name, package_hidden)
+		parse_distinct(parser, name, visibility)
 		return
 	}
 	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Alias {
-		parse_alias(parser, name, package_hidden)
+		parse_alias(parser, name, visibility)
 		return
 	}
 
@@ -3398,7 +3496,7 @@ parse_top_level :: proc(parser: ^Parser) {
 		name=name.symbol,
 		pkg=parser.pkg,
 		file=parser.file,
-		package_hidden=package_hidden,
+		visibility=visibility,
 		type=type_syntax,
 		immutable=operator.kind == .Colon_Colon,
 		expr=expr,
@@ -3419,9 +3517,9 @@ parse :: proc(
 		diagnostics=diagnostics,
 		module=ast.init_module(allocator),
 	}
-	parser.hidden_names.allocator = allocator
-	defer delete(parser.hidden_names)
-	collect_hidden_names(&parser)
+	parser.local_names.allocator = allocator
+	defer delete(parser.local_names)
+	collect_local_names(&parser)
 	skip_newlines(&parser)
 	for current(&parser).kind != .Eof {
 		parse_top_level(&parser)
@@ -3446,9 +3544,9 @@ parse_into :: proc(
 		pkg=pkg,
 		file=file,
 	}
-	parser.hidden_names.allocator = module.allocator
-	defer delete(parser.hidden_names)
-	collect_hidden_names(&parser)
+	parser.local_names.allocator = module.allocator
+	defer delete(parser.local_names)
+	collect_local_names(&parser)
 	skip_newlines(&parser)
 	for current(&parser).kind != .Eof {
 		parse_top_level(&parser)

compiler/testing.odin

@@ -175,7 +175,7 @@ append_runner :: proc(
 	for entry, index in tests {
 		test := module.functions[entry.function]
 		alias := fmt.tprintf("__brolang_test_%d", index)
-		fmt.sbprintf(&builder, "hide __brolang_test_adapter_%d func() void ! __brolang_testing.Error ", index)
+		fmt.sbprintf(&builder, "@hide __brolang_test_adapter_%d func() void ! __brolang_testing.Error ", index)
 		strings.write_string(&builder, "{\n\t")
 		fmt.sbprintf(&builder, "%s.%s() catch |_| ", alias, symbol.resolve(symbols, test.name))
 		strings.write_string(&builder, "{\n\t\treturn .expectation_failed\n\t}\n}\n\n")

compiler/token/token.odin

@@ -72,7 +72,6 @@ Kind :: enum u8 {
 	Keyword_Distinct,
 	Keyword_Alias,
 	Keyword_Import,
-	Keyword_Hide,
 	Keyword_Return,
 	Keyword_Try,
 	Keyword_Catch,

compiler/types/types.odin

@@ -56,6 +56,12 @@ Numeric_Category :: enum u8 {
 	Float,
 }
 
+Visibility :: enum u8 {
+	Public,
+	Package,
+	File,
+}
+
 Kind :: enum u8 {
 	Invalid,
 	Void,
@@ -109,7 +115,7 @@ Node :: struct {
 	tuple:        bool,
 	opaque:       bool,
 	declared:     bool,
-	package_hidden: bool,
+	visibility:   Visibility,
 	explicit_backing: bool,
 }
 
@@ -193,13 +199,21 @@ intern :: proc(store: ^Store, candidate: Node) -> Type {
 	return id
 }
 
-named :: proc(store: ^Store, pkg, name: u32, qualifier: u32 = 0, file: u32 = 0xffff_ffff, package_hidden := false) -> Type {
-	normalized_file := file if qualifier != 0 else u32(0)
+named :: proc(
+	store: ^Store,
+	pkg, name: u32,
+	qualifier: u32 = 0,
+	file: u32 = 0xffff_ffff,
+	visibility := Visibility.Public,
+) -> Type {
+	normalized_file := file if qualifier != 0 || visibility == .File else u32(0)
 	for existing, index in store.nodes {
 		if (existing.kind == .Named || existing.kind == .Alias || existing.kind == .Distinct ||
 		    existing.kind == .Enum || existing.kind == .Struct || existing.kind == .Union) &&
 		   existing.pkg == pkg && existing.name == name && existing.qualifier == qualifier &&
-		   (qualifier == 0 || existing.file == normalized_file) {
+		   ((qualifier != 0 && existing.file == normalized_file) ||
+		    (qualifier == 0 && visibility == .File && existing.visibility == .File && existing.file == normalized_file) ||
+		    (qualifier == 0 && visibility != .File && existing.visibility != .File)) {
 			return DYNAMIC_START+Type(index)
 		}
 	}
@@ -209,22 +223,41 @@ named :: proc(store: ^Store, pkg, name: u32, qualifier: u32 = 0, file: u32 = 0xf
 		name=name,
 		qualifier=qualifier,
 		file=normalized_file,
+		visibility=visibility,
 	})
 }
 
 find_named :: proc(store: ^Store, pkg, name: u32, qualifier: u32 = 0, file: u32 = 0xffff_ffff) -> Type {
+	fallback := INVALID
 	for existing, index in store.nodes {
-		if (existing.kind == .Named || existing.kind == .Alias || existing.kind == .Distinct ||
-		    existing.kind == .Enum || existing.kind == .Struct || existing.kind == .Union) &&
-		   existing.pkg == pkg && existing.name == name && existing.qualifier == qualifier &&
-		   (!existing.package_hidden || file != 0xffff_ffff) {
-			return DYNAMIC_START+Type(index)
+		if (existing.kind != .Named && existing.kind != .Alias && existing.kind != .Distinct &&
+		    existing.kind != .Enum && existing.kind != .Struct && existing.kind != .Union) ||
+		   existing.pkg != pkg || existing.name != name || existing.qualifier != qualifier {
+			continue
+		}
+		if qualifier != 0 {
+			if existing.file == file {
+				return DYNAMIC_START+Type(index)
+			}
+			continue
+		}
+		switch existing.visibility {
+		case .Public:
+			fallback = DYNAMIC_START+Type(index)
+		case .Package:
+			if file != 0xffff_ffff {
+				fallback = DYNAMIC_START+Type(index)
+			}
+		case .File:
+			if existing.file == file {
+				return DYNAMIC_START+Type(index)
+			}
 		}
 	}
-	return INVALID
+	return fallback
 }
 
-define_alias :: proc(store: ^Store, id, child: Type, package_hidden := false) -> bool {
+define_alias :: proc(store: ^Store, id, child: Type, visibility := Visibility.Public) -> bool {
 	existing, ok := node(store, id)
 	if !ok || existing.kind != .Named || existing.declared {
 		return false
@@ -232,12 +265,12 @@ define_alias :: proc(store: ^Store, id, child: Type, package_hidden := false) ->
 	index := int(id-DYNAMIC_START)
 	store.nodes[index].kind = .Alias
 	store.nodes[index].child = child
-	store.nodes[index].package_hidden = package_hidden
+	store.nodes[index].visibility = visibility
 	store.nodes[index].declared = true
 	return true
 }
 
-define_distinct :: proc(store: ^Store, id, child: Type, package_hidden := false) -> bool {
+define_distinct :: proc(store: ^Store, id, child: Type, visibility := Visibility.Public) -> bool {
 	existing, ok := node(store, id)
 	if !ok || existing.kind != .Named || existing.declared {
 		return false
@@ -245,12 +278,12 @@ define_distinct :: proc(store: ^Store, id, child: Type, package_hidden := false)
 	index := int(id-DYNAMIC_START)
 	store.nodes[index].kind = .Distinct
 	store.nodes[index].child = child
-	store.nodes[index].package_hidden = package_hidden
+	store.nodes[index].visibility = visibility
 	store.nodes[index].declared = true
 	return true
 }
 
-define_enum :: proc(store: ^Store, id, backing: Type, members: []Enum_Member, explicit_backing: bool, package_hidden := false) -> bool {
+define_enum :: proc(store: ^Store, id, backing: Type, members: []Enum_Member, explicit_backing: bool, visibility := Visibility.Public) -> bool {
 	existing, ok := node(store, id)
 	if !ok || existing.kind != .Named || existing.declared {
 		return false
@@ -261,7 +294,7 @@ define_enum :: proc(store: ^Store, id, backing: Type, members: []Enum_Member, ex
 	store.nodes[index].field_start = u32(len(store.enum_members))
 	store.nodes[index].field_count = u32(len(members))
 	store.nodes[index].explicit_backing = explicit_backing
-	store.nodes[index].package_hidden = package_hidden
+	store.nodes[index].visibility = visibility
 	store.nodes[index].declared = true
 	append(&store.enum_members, ..members)
 	return true
@@ -278,7 +311,7 @@ define_record :: proc(
 	tag: Type = INVALID,
 	declared_tag: Type = INVALID,
 	tuple := false,
-	package_hidden := false,
+	visibility := Visibility.Public,
 ) -> bool {
 	existing, ok := node(store, id)
 	if !ok || (existing.kind != .Named && existing.kind != .Struct && existing.kind != .Union) ||
@@ -290,7 +323,7 @@ define_record :: proc(
 	store.nodes[index].c_layout = c_layout
 	store.nodes[index].tuple = tuple
 	store.nodes[index].opaque = opaque
-	store.nodes[index].package_hidden = package_hidden
+	store.nodes[index].visibility = visibility
 	store.nodes[index].declared = true
 	store.nodes[index].explicit_size = explicit_size
 	store.nodes[index].explicit_alignment = explicit_alignment
@@ -636,6 +669,43 @@ fields_for :: proc(store: ^Store, value: Type) -> []Field {
 	return store.fields[start:end]
 }
 
+field_layout_precedes :: proc(
+	store: ^Store,
+	value: Type,
+	left, right: int,
+	selected := target.DEFAULT,
+) -> bool {
+	fields := fields_for(store, value)
+	item, ok := node(store, value)
+	if !ok || item.kind != .Struct || item.c_layout ||
+	   left < 0 || left >= len(fields) || right < 0 || right >= len(fields) {
+		return left < right
+	}
+	left_alignment := alignment_of(fields[left].type, store, selected)
+	right_alignment := alignment_of(fields[right].type, store, selected)
+	return left_alignment > right_alignment ||
+	       (left_alignment == right_alignment && left < right)
+}
+
+physical_field_index :: proc(
+	store: ^Store,
+	value: Type,
+	logical_index: int,
+	selected := target.DEFAULT,
+) -> int {
+	fields := fields_for(store, value)
+	if logical_index < 0 || logical_index >= len(fields) {
+		return logical_index
+	}
+	result := 0
+	for _, other_index in fields {
+		if field_layout_precedes(store, value, other_index, logical_index, selected) {
+			result += 1
+		}
+	}
+	return result
+}
+
 params_for :: proc(store: ^Store, value: Type) -> []Field {
 	item, ok := node(store, value)
 	if !ok || item.kind != .Function {
@@ -1709,11 +1779,18 @@ size :: proc(value: Type, store: ^Store, selected := target.DEFAULT) -> u64 {
 		}
 		offset: u64
 		max_align: u64 = 1
-		for field in fields_for(store, value) {
-			field_align := u64(alignment_of(field.type, store, selected))
-			offset = (offset+field_align-1)/field_align*field_align
-			offset += size(field.type, store, selected)
-			max_align = max(max_align, field_align)
+		if !item.c_layout {
+			for field in fields_for(store, value) {
+				offset += size(field.type, store, selected)
+				max_align = max(max_align, u64(alignment_of(field.type, store, selected)))
+			}
+		} else {
+			for field in fields_for(store, value) {
+				field_align := u64(alignment_of(field.type, store, selected))
+				offset = (offset+field_align-1)/field_align*field_align
+				offset += size(field.type, store, selected)
+				max_align = max(max_align, field_align)
+			}
 		}
 		return (offset+max_align-1)/max_align*max_align
 	case .Union:

compiler_tests.odin

@@ -1257,6 +1257,29 @@ main func() void {}
 	testing.expect_value(t, module.imports[2].path, "dir\"name\\tail")
 }
 
+@(test)
+honey_hex_byte_string_escapes_decode_to_bytes :: proc(t: ^testing.T) {
+	text := `value :: "\x1b[31m\x00\xFf"
+main func() void {}
+`
+	source_file := source.Source{path="test.hon", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&module)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect_value(t, len(module.strings), 1)
+	testing.expect_value(t, len(module.strings[0]), 7)
+	testing.expect_value(t, module.strings[0][0], byte(0x1b))
+	testing.expect_value(t, module.strings[0][5], byte(0))
+	testing.expect_value(t, module.strings[0][6], byte(0xff))
+}
+
 @(test)
 parser_accepts_chained_field_access :: proc(t: ^testing.T) {
 	text := `main func() void {
@@ -1278,7 +1301,7 @@ parser_accepts_chained_field_access :: proc(t: ^testing.T) {
 
 @(test)
 lexer_diagnoses_invalid_import_strings :: proc(t: ^testing.T) {
-	text := "import \"bad\\q\"\nimport \"unterminated\n"
+	text := "import \"bad\\q\"\nimport \"bad\\xg0\"\nimport \"bad\\x1\"\nimport \"unterminated\n"
 	source_file := source.Source{path="test.bro", text=text}
 	diagnostics := source.init_diagnostics(&source_file)
 	defer source.destroy_diagnostics(&diagnostics)
@@ -1287,7 +1310,7 @@ lexer_diagnoses_invalid_import_strings :: proc(t: ^testing.T) {
 	stream := lexer.lex(&source_file, &diagnostics, &symbols)
 	defer delete(stream.items)
 
-	testing.expect_value(t, len(diagnostics.items), 2)
+	testing.expect_value(t, len(diagnostics.items), 4)
 }
 
 @(test)
@@ -1867,6 +1890,92 @@ many_item_pointer_slices_require_end_bound :: proc(t: ^testing.T) {
 	testing.expect_value(t, end_bound_errors, 2)
 }
 
+@(test)
+indices_and_slice_bounds_require_usize :: proc(t: ^testing.T) {
+	text := `Index :: distinct u32
+main func() void {
+	values [2]i32 := [1, 2]
+	index := 1
+	start := 0
+	end := 1
+	small u32 := 0
+	id Index := Index(0)
+	_ = values[index]
+	_ = values[start..end]
+	_ = values[small]
+	_ = values[id]
+	_ = values[small..]
+	_ = values[..id]
+}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+
+	index_errors, bound_errors := 0, 0
+	for diagnostic in diagnostics.items {
+		index_errors += 1 if strings.contains(diagnostic.message, "index must have type usize") else 0
+		bound_errors += 1 if strings.contains(diagnostic.message, "slice bound must have type usize") else 0
+	}
+	testing.expect_value(t, len(diagnostics.items), 4)
+	testing.expect_value(t, index_errors, 2)
+	testing.expect_value(t, bound_errors, 2)
+}
+
+@(test)
+comptime_indices_infer_usize_and_reject_explicit_integer_types :: proc(t: ^testing.T) {
+	text := `good func($items [2]u8) u8 {
+	start := 0
+	end := 1
+	part :: items[start..end]
+	return part[start]
+}
+bad_index func($items [2]u8) u8 {
+	cursor u32 := 0
+	return items[cursor]
+}
+bad_bound func($items [2]u8) u8 {
+	start u32 := 0
+	return items[start..][0]
+}
+GOOD :: $good([7, 8])
+BAD_INDEX :: $bad_index([7, 8])
+BAD_BOUND :: $bad_bound([7, 8])
+main func() void {
+	_ = GOOD
+	_ = BAD_INDEX
+	_ = BAD_BOUND
+}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+
+	testing.expect_value(t, len(diagnostics.items), 2)
+	index_error, bound_error := false, false
+	for diagnostic in diagnostics.items {
+		index_error = index_error || strings.contains(diagnostic.message, "index must have type usize, got u32")
+		bound_error = bound_error || strings.contains(diagnostic.message, "slice bound must have type usize, got u32")
+	}
+	testing.expect(t, index_error && bound_error)
+}
+
 @(test)
 layout_builtins_compile_and_run :: proc(t: ^testing.T) {
 	directory := "/tmp/brolang-test-layout-builtins"
@@ -1887,6 +1996,18 @@ Bool_Last :: struct {
 	flag bool
 }
 
+Optimized :: struct {
+	prefix u8
+	wide u64
+	suffix u8
+}
+
+Source_Order_C :: c_struct {
+	prefix c_uchar
+	wide c_ulong
+	suffix c_uchar
+}
+
 Opaque :: opaque
 Color :: enum {
 	red
@@ -1937,12 +2058,19 @@ main func() i32 {
 	if (sizeof!(bool) != 1) return 15
 	if (sizeof!(Bool_First) != 2) return 16
 	if (sizeof!(Bool_Last) != 2) return 17
+	optimized Optimized := Optimized{prefix = 40, wide = 72623859790382856, suffix = 41}
+	if (sizeof!(Optimized) != 16) return 18
+	if (alignof!(Optimized) != 8) return 19
+	if (sizeof!(Source_Order_C) != 24) return 20
+	if (optimized.prefix != 40) return 21
+	if (optimized.wide != 72623859790382856) return 22
+	if (optimized.suffix != 41) return 23
 	first :: make_bool_first()
-	if (!first.flag) return 18
-	if (first.byte != 41) return 19
+	if (!first.flag) return 24
+	if (first.byte != 41) return 25
 	last :: make_bool_last()
-	if (!last.flag) return 20
-	if (last.byte != 42) return 21
+	if (!last.flag) return 26
+	if (last.byte != 42) return 27
 	return 0
 }
 `
@@ -3110,6 +3238,200 @@ bodyless_root_main_recovers_as_a_trap_definition :: proc(t: ^testing.T) {
 	testing.expect(t, !strings.contains(llvm_text, "declare i32 @main()"))
 }
 
+@(test)
+fallible_main_maps_success_and_error_channels_to_exit_codes :: proc(t: ^testing.T) {
+	Case :: struct {
+		name:      string,
+		source:    string,
+		exit_code: int,
+	}
+	cases := [?]Case{
+		{
+			name="void-success",
+			source=`Error :: enum { failed }
+succeed func() void ! Error {}
+main func() void ! Error { try succeed() }
+`,
+			exit_code=0,
+		},
+		{
+			name="void-error",
+			source=`Error :: enum { failed }
+fail func() void ! Error { return .failed }
+main func() void ! Error { try fail() }
+`,
+			exit_code=1,
+		},
+		{
+			name="int-success",
+			source=`Error :: enum { failed }
+value func() i32 ! Error { return 7 }
+main func() int ! Error { return try value() }
+`,
+			exit_code=7,
+		},
+		{
+			name="process-error",
+			source=`process :: import "@std/process"
+Error :: enum { failed }
+fail func() void ! Error { return .failed }
+main func(_ process.Init) void ! Error { try fail() }
+`,
+			exit_code=1,
+		},
+		{
+			name="inferred-main-try",
+			source=`Error :: enum { failed }
+fail func() void ! Error { return .failed }
+main func() void! { try fail() }
+`,
+			exit_code=1,
+		},
+		{
+			name="inferred-main-typed-return",
+			source=`Error :: enum { failed }
+main func() void! {
+	err Error := .failed
+	return err
+}
+`,
+			exit_code=1,
+		},
+		{
+			name="inferred-hidden-sum",
+			source=`A :: enum { a }
+B :: enum { b }
+fail_a func() void ! A { return .a }
+fail_b func() void ! B { return .b }
+@hide dispatch func(selector i32) void! {
+	if selector == 1 {
+		try fail_a()
+		return
+	}
+	try fail_b()
+}
+main func() void! { try dispatch(2) }
+`,
+			exit_code=1,
+		},
+		{
+			name="inferred-process-main",
+			source=`process :: import "@std/process"
+Error :: enum { failed }
+fail func() void ! Error { return .failed }
+main func(_ process.Init) void! { try fail() }
+`,
+			exit_code=1,
+		},
+	}
+	for test_case in cases {
+		directory := fmt.tprintf("/tmp/brolang-test-fallible-main-%s", test_case.name)
+		output := fmt.tprintf("%s/app", directory)
+		_ = os2.remove_all(directory)
+		defer _ = os2.remove_all(directory)
+		testing.expect(t, os.make_directory(directory) == nil)
+		testing.expect(t, os.write_entire_file(
+			fmt.tprintf("%s/main.bro", directory),
+			transmute([]byte)test_case.source,
+		))
+		status := compiler_core.compile_package(
+			directory,
+			output,
+			nil,
+			target.DEFAULT,
+			cimport.Options{},
+			".",
+		)
+		testing.expect_value(t, status, 0)
+		state, stdout, stderr, _ := os2.process_exec(
+			os2.Process_Desc{command=[]string{output}},
+			context.allocator,
+		)
+		defer delete(stdout)
+		defer delete(stderr)
+		testing.expect_value(t, state.exit_code, test_case.exit_code)
+		testing.expect_value(t, len(stdout), 0)
+		testing.expect_value(t, len(stderr), 0)
+	}
+}
+
+@(test)
+inferred_error_channels_reject_unstable_or_untyped_contracts :: proc(t: ^testing.T) {
+	Case :: struct {
+		source:  string,
+		message: string,
+		absent:  string,
+	}
+	cases := [?]Case{
+		{
+			source=`Error :: enum { failed }
+fail func() void ! Error { return .failed }
+visible func() void! { try fail() }
+main func() void {}
+`,
+			message="inferred error channels are only allowed on local functions and root main",
+		},
+		{
+			source=`Error :: enum { failed }
+fail func() void ! Error { return .failed }
+@hide untyped func(flag bool) void! {
+	if flag {
+		try fail()
+		return
+	}
+	return .failed
+}
+main func() void { untyped(false) catch |_| {} }
+`,
+			message="inferred error returns require a concretely typed error value",
+		},
+		{
+			source=`@hide empty func() void! {}
+main func() void { empty() catch |_| {} }
+`,
+			message="could not infer a named error channel for 'empty'",
+		},
+		{
+			source=`Error :: enum { failed }
+fail func() void ! Error { return .failed }
+value func() i32 { return 1 }
+main func() void! {
+	fail() catch |_| {
+		return
+	}
+	_ = try value()
+}
+`,
+			message="could not infer a named error channel for 'main'",
+			absent="non-void function must return a value",
+		},
+	}
+	for test_case in cases {
+		source_file := source.Source{path="test.bro", text=test_case.source}
+		diagnostics := source.init_diagnostics(&source_file)
+		symbols := symbol.init_table()
+		stream := lexer.lex(&source_file, &diagnostics, &symbols)
+		ast_module := parser.parse(&stream, &source_file, &diagnostics)
+		hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+
+		found := false
+		unexpected := false
+		for diagnostic in diagnostics.items {
+			found = found || strings.contains(diagnostic.message, test_case.message)
+			unexpected = unexpected ||
+			             len(test_case.absent) > 0 && strings.contains(diagnostic.message, test_case.absent)
+		}
+		testing.expect(t, found)
+		testing.expect(t, !unexpected)
+
+		hir.destroy_module(&hir_module)
+		ast.destroy_module(&ast_module)
+		delete(stream.items)
+		symbol.destroy_table(&symbols)
+		source.destroy_diagnostics(&diagnostics)
+	}
+}
+
 @(test)
 milestone_33_injects_explicit_io_provider_and_runs_std_io :: proc(t: ^testing.T) {
 	sources := source.init_store()
@@ -3364,11 +3686,11 @@ system func() Io { return Io {value = 0} }
 			process_source=`io :: import "@std/io"
 Init :: struct { io io.Io }
 `,
-			message="does not provide the required 'hide system func() Io'",
+			message="does not provide the required '@hide system func() Io'",
 		},
 		{
 			io_source=`Io :: struct { value i32 }
-hide system func() Io { return Io {value = 0} }
+@hide system func() Io { return Io {value = 0} }
 `,
 			process_source=`io :: import "@std/io"
 Init :: struct { io io.Io, extra i32 }
@@ -5894,7 +6216,7 @@ milestone_24_rejects_invalid_forms :: proc(t: ^testing.T) {
 	}
 	cases := [?]Case{
 		{"examples/programs/index_signed_error", "/tmp/brolang-test-index-signed-error"},
-		{"examples/programs/index_int_constraint_error", "/tmp/brolang-test-index-int-constraint-error"},
+		{"examples/programs/index_unsigned_error", "/tmp/brolang-test-index-unsigned-error"},
 		{"examples/programs/scalar_cast_error", "/tmp/brolang-test-scalar-cast-error"},
 		{"examples/programs/array_const_size_error", "/tmp/brolang-test-array-const-size-error"},
 	}
@@ -6953,6 +7275,51 @@ main func() i32 {
 	testing.expect_value(t, state.exit_code, 0)
 }
 
+@(test)
+struct_error_channels_compile_and_run_at_runtime_and_comptime :: proc(t: ^testing.T) {
+	text := `ScanError :: struct {
+	code i32
+	start usize
+	end usize
+}
+scan func(fail bool) i32 ! ScanError {
+	if fail {
+		return ScanError { code = 5, start = 7, end = 11 }
+	}
+	return 41
+}
+scan_local func() i32 ! ScanError {
+	err ScanError := ScanError { code = 3, start = 13, end = 17 }
+	return err
+}
+forward func(fail bool) i32 ! ScanError {
+	return try scan(fail)
+}
+score_comptime func() i32 {
+	return scan(true) catch |err| err.code + i32(err.start) + i32(err.end)
+}
+main func() i32 {
+	direct :: scan(true) catch |err| err.code + i32(err.start) + i32(err.end)
+	local :: scan_local() catch |err| err.code + i32(err.start) + i32(err.end)
+	forwarded :: forward(true) catch |err| err.code + i32(err.start) + i32(err.end)
+	success :: forward(false) catch 0
+	comptime_score i32 :: $score_comptime()
+	return direct + local + forwarded + success + comptime_score - 143
+}
+`
+	directory := "/tmp/brolang-test-struct-error-channel"
+	main_path := "/tmp/brolang-test-struct-error-channel/main.bro"
+	output := "/tmp/brolang-test-struct-error-channel-output"
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(output)
+	testing.expect(t, os.make_directory(directory) == nil)
+	testing.expect(t, os.write_entire_file(main_path, transmute([]byte)text))
+	testing.expect_value(t, compiler_core.compile_package(directory, output), 0)
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 0)
+}
+
 @(test)
 matched_error_residuals_return_at_runtime_and_comptime :: proc(t: ^testing.T) {
 	text := `KeyError :: enum { key_exists }
@@ -10106,14 +10473,18 @@ imports_are_file_local :: proc(t: ^testing.T) {
 }
 
 @(test)
-hide_is_rejected_outside_named_top_level_declarations :: proc(t: ^testing.T) {
+visibility_modifiers_are_rejected_outside_named_top_level_declarations :: proc(t: ^testing.T) {
 	cases := [?]string{
-		`hide import "../dep"`,
-		`hide dep :: import "../dep"`,
-		`hide func() void {}`,
-		`main func(hide value i32) void {}`,
-		`Box :: struct { hide i32 }`,
-		`main func() void { hide value i32 := 1 }`,
+		`@hide import "../dep"`,
+		`@hide:file dep :: import "../dep"`,
+		`@hide func() void {}`,
+		`main func(@hide value i32) void {}`,
+		`Box :: struct { @hide i32 }`,
+		`main func() void { @hide value i32 := 1 }`,
+		`@hide: value :: 1`,
+		`@hide:module value :: 1`,
+		`@hide:"file" value :: 1`,
+		`@hide(file) value :: 1`,
 	}
 	for text in cases {
 		source_file := source.Source{path="test.bro", text=text}
@@ -10131,17 +10502,17 @@ hide_is_rejected_outside_named_top_level_declarations :: proc(t: ^testing.T) {
 }
 
 @(test)
-hide_declarations_are_package_hidden :: proc(t: ^testing.T) {
-	output := "/tmp/brolang-test-hidden-declarations"
+local_declarations_resolve_at_their_declared_scope :: proc(t: ^testing.T) {
+	output := "/tmp/brolang-test-local-declarations"
 	defer _ = os.remove(output)
 	status := compiler_core.compile_package("examples/packages/hidden_valid/app", output)
 	testing.expect_value(t, status, 0)
 	state := run_executable(output)
-	testing.expect_value(t, state.exit_code, 9)
+	testing.expect_value(t, state.exit_code, 15)
 }
 
 @(test)
-package_hidden_declarations_resolve_locally_but_not_through_imports :: proc(t: ^testing.T) {
+package_and_file_local_visibility_is_enforced :: proc(t: ^testing.T) {
 	sources := source.init_store()
 	defer source.destroy_store(&sources)
 	diagnostics := source.init_store_diagnostics(&sources)
@@ -10159,18 +10530,27 @@ package_hidden_declarations_resolve_locally_but_not_through_imports :: proc(t: ^
 	found_sibling_type := false
 	found_import := false
 	found_collision := false
+	found_file_sibling := false
+	found_file_sibling_value := false
+	found_file_sibling_type := false
 	for diagnostic in diagnostics.items {
 		found_sibling = found_sibling || strings.contains(diagnostic.message, "unknown symbol 'sibling'")
 		found_sibling_value = found_sibling_value || strings.contains(diagnostic.message, "unknown symbol 'sibling_value'")
 		found_sibling_type = found_sibling_type || strings.contains(diagnostic.message, "unknown or opaque record type 'Sibling'")
 		found_import = found_import || strings.contains(diagnostic.message, "package 'dep' has no member 'secret'")
 		found_collision = found_collision || strings.contains(diagnostic.message, "duplicate function 'collision'")
+		found_file_sibling = found_file_sibling || strings.contains(diagnostic.message, "unknown symbol 'file_sibling'")
+		found_file_sibling_value = found_file_sibling_value || strings.contains(diagnostic.message, "unknown symbol 'file_sibling_value'")
+		found_file_sibling_type = found_file_sibling_type || strings.contains(diagnostic.message, "unknown symbol 'File_Sibling'")
 	}
 	testing.expect(t, !found_sibling)
 	testing.expect(t, !found_sibling_value)
 	testing.expect(t, !found_sibling_type)
 	testing.expect(t, found_import)
 	testing.expect(t, found_collision)
+	testing.expect(t, found_file_sibling)
+	testing.expect(t, found_file_sibling_value)
+	testing.expect(t, found_file_sibling_type)
 }
 
 @(test)
@@ -10297,7 +10677,7 @@ MaybePoint :: alias ?@dep.Point
 Concrete :: alias dep.Box(i32)
 `
 	hidden_text := `dep :: import "../dep"
-hide local_answer_alias :: alias dep.answer
+@hide local_answer_alias :: alias dep.answer
 `
 	top_text := `facade :: import "../facade"
 Box :: alias facade.RenamedBox
@@ -10421,7 +10801,7 @@ declaration_aliases_diagnose_invalid_targets :: proc(t: ^testing.T) {
 		testing.expect(t, os.make_directory(directory) == nil)
 	}
 	dep_text := `visible func() i32 { return 1 }
-hide hidden_target func() i32 { return 2 }
+@hide hidden_target func() i32 { return 2 }
 ambiguous func() i32 { return 3 }
 ambiguous i32 :: 4
 `
@@ -10465,7 +10845,7 @@ main func() void {}
 	testing.expect(t, loaded)
 	wants := []string{
 		"has no member 'missing'",
-		"is package-hidden",
+		"is not public",
 		"unknown symbol 'nope'",
 		"unavailable imported package 'gone'",
 		"package member 'dep.ambiguous' is ambiguous",
@@ -11243,6 +11623,39 @@ braceless_while_compiles_and_runs :: proc(t: ^testing.T) {
 	testing.expect_value(t, state.exit_code, 42)
 }
 
+@(test)
+while_unwrap_compiles_and_runs_at_runtime_and_comptime :: proc(t: ^testing.T) {
+	directory := "/tmp/brolang-test-while-unwrap"
+	main_path := "/tmp/brolang-test-while-unwrap/main.bro"
+	output := "/tmp/brolang-test-while-unwrap-output"
+	text := `next func(index @mut usize, limit usize) ?i32 {
+	if (index^ == limit) return null
+	index^ += 1
+	return i32(index^)
+}
+sum func(limit, cap usize) i32 {
+	index usize := 0
+	total i32 := 0
+	while next(&index, limit) |value : usize(value) <= cap| : total += value {}
+	return total
+}
+COMPTIME_SUM :: $sum(4, 4)
+COMPTIME_GUARDED :: $sum(5, 3)
+main func() i32 {
+	if COMPTIME_SUM != 10 or COMPTIME_GUARDED != 6 { return 1 }
+	return sum(4, 4) + sum(5, 3) - 16
+}
+`
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(output)
+	testing.expect(t, os.make_directory(directory) == nil)
+	testing.expect(t, os.write_entire_file(main_path, transmute([]byte)text))
+	testing.expect_value(t, compiler_core.compile_package(directory, output), 0)
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 0)
+}
+
 @(test)
 parser_diagnoses_braceless_for_and_unwrap_without_parens_or_call :: proc(t: ^testing.T) {
 	text := `main func() void {
@@ -13894,7 +14307,6 @@ main func() i32 {
 @(test)
 keywords_are_valid_enum_members_and_tagged_union_variants :: proc(t: ^testing.T) {
 	testing.expect(t, token.is_keyword(.Keyword_Func))
-	testing.expect(t, token.is_keyword(.Keyword_Hide))
 	testing.expect(t, token.is_keyword(.Keyword_C_Longdouble))
 	testing.expect(t, !token.is_keyword(.Identifier))
 	testing.expect(t, !token.is_keyword(.Underscore))
@@ -13909,6 +14321,9 @@ Token :: union(TokenKind) {
 	else void
 	return i32
 }
+hide func() i32 { return 0 }
+package func() i32 { return 0 }
+file func() i32 { return 0 }
 kind func(value bool) TokenKind {
 	if value {
 		return .if
@@ -13921,7 +14336,7 @@ main func() i32 {
 	a Token := Token{ if = 1 }
 	b Token := Token{ else }
 	c Token := .return{2}
-	total i32 := a.if + c.return
+	total i32 := a.if + c.return + hide() + package() + file()
 	match first {
 		.if: total = total + 1
 		.else: total = total + 2
@@ -14771,6 +15186,34 @@ missing_qualified_signature_symbol_reports_one_root_error :: proc(t: ^testing.T)
 	testing.expect(t, !strings.contains(formatted, "could not resolve the 'int' constraint"))
 }
 
+@(test)
+missing_unqualified_signature_type_reports_one_root_error :: proc(t: ^testing.T) {
+	text := `render_stmt func(node NodeId) void {}
+main func() void {
+	render_stmt(0)
+}
+`
+	source_file := source.Source{path="renderer.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+
+	testing.expect_value(t, len(diagnostics.items), 1)
+	testing.expect_value(t, diagnostics.items[0].message, "unknown symbol 'NodeId'")
+	formatted := source.format(&diagnostics, source.Diagnostic_Id(0))
+	defer delete(formatted)
+	testing.expect(t, strings.contains(formatted, "renderer.bro:1:23"))
+	testing.expect(t, strings.contains(formatted, "^^^^^^ unknown symbol"))
+	testing.expect(t, !strings.contains(formatted, "could not resolve specialization"))
+}
+
 @(test)
 poisoned_global_and_local_types_do_not_create_inference_fallbacks :: proc(t: ^testing.T) {
 	directory := "/tmp/brolang-test-poisoned-declarations"
@@ -14865,7 +15308,19 @@ exercise func(cursor usize, narrow i8, wider i16, count i32) i32 {
 	return 0
 }
 
-main func() i32 { return exercise(7, 1, 1000, 3) }
+scan_open_cursor func() void {
+	cursor := 0
+	first Token := Token{start = cursor}
+	second Token := Token{start = cursor}
+	_ = first
+	_ = second
+}
+
+main func() i32 {
+	result := exercise(7, 1, 1000, 3)
+	scan_open_cursor()
+	return result
+}
 `
 	source_file := source.Source{path="record_constraints.bro", text=text}
 	diagnostics := source.init_diagnostics(&source_file)
@@ -15136,12 +15591,12 @@ dependency_passes test {
 	defer delete(stderr)
 	output := string(stderr)
 	testing.expect_value(t, state.exit_code, 1)
-	testing.expect(t, strings.contains(output, "root.root_passes...[ok]"))
-	testing.expect(t, strings.contains(output, "root.root_fails...[failed]"))
+	testing.expect(t, strings.contains(output, "root.root_passes...[\x1b[92mok\x1b[0m]"))
+	testing.expect(t, strings.contains(output, "root.root_fails...[\x1b[91mfailure\x1b[0m]"))
 	testing.expect(t, strings.contains(output, "expected 42, found 41"))
-	testing.expect(t, strings.contains(output, "root.root_continues...[ok]"))
-	testing.expect(t, strings.contains(output, "root.root_errors...[failed]"))
-	testing.expect(t, strings.contains(output, "dependency.dependency_passes...[ok]"))
+	testing.expect(t, strings.contains(output, "root.root_continues...[\x1b[92mok\x1b[0m]"))
+	testing.expect(t, strings.contains(output, "root.root_errors...[\x1b[91mfailure\x1b[0m]"))
+	testing.expect(t, strings.contains(output, "dependency.dependency_passes...[\x1b[92mok\x1b[0m]"))
 	testing.expect(t, strings.contains(output, root_path))
 	testing.expect(t, strings.contains(output, "3 passed, 2 failed"))
 }

examples/packages/hidden_invalid/app/a.bro

@@ -1,12 +1,22 @@
-hide sibling func() i32 {
+@hide sibling func() i32 {
 	return 1
 }
 
-hide Sibling :: struct {
+@hide Sibling :: struct {
 	value i32
 }
 
-hide sibling_value :: 1
+@hide sibling_value :: 1
+
+@hide:file file_sibling func() i32 {
+	return 1
+}
+
+@hide:file File_Sibling :: struct {
+	value i32
+}
+
+@hide:file file_sibling_value :: 1
 
 collision c_func() i32 {
 	return 1

examples/packages/hidden_invalid/app/b.bro

@@ -1,6 +1,6 @@
 import "../dep"
 
-hide collision func() i32 {
+@hide collision func() i32 {
 	return 2
 }
 
@@ -12,6 +12,12 @@ read_sibling_value func() i32 {
 	return sibling_value
 }
 
-main func() i32 {
-	return sibling() + dep.secret() + read_sibling(Sibling { value = 1 }) + read_sibling_value()
+read_file_sibling func(value File_Sibling) i32 {
+	return value.value
+}
+
+main func() i32 {
+	return file_sibling() + file_sibling_value + sibling() + dep.secret() +
+	       read_sibling(Sibling { value = 1 }) + read_sibling_value() +
+	       read_file_sibling(File_Sibling { value = 1 })
 }

examples/packages/hidden_invalid/dep/dep.bro

@@ -1,3 +1,3 @@
-hide secret c_func() i32 {
+@hide:package secret c_func() i32 {
 	return 1
 }

examples/packages/hidden_valid/app/a.bro

@@ -1,26 +1,28 @@
-hide helper func() i32 {
+@hide:package
+helper func() i32 {
 	thing Thing := Thing { value = value }
 	return thing.value
 }
 
-hide Thing :: struct {
+@hide
+Thing :: struct {
 	value i32
 }
 
-hide Local_Union :: union {
+@hide Local_Union :: union {
 	value i32
 }
 
-hide Local_Enum :: enum {
+@hide Local_Enum :: enum {
 	value
 }
 
-hide Local_Opaque :: opaque
-hide Local_Distinct :: distinct i32
-hide Local_Alias :: alias i32
+@hide Local_Opaque :: opaque
+@hide Local_Distinct :: distinct i32
+@hide Local_Alias :: alias i32
 
-hide value :: 1
-hide mutable_value i32 := 1
+@hide value :: 1
+@hide mutable_value i32 := 1
 
 _foreign c_func() i32 {
 	return 1
@@ -30,15 +32,27 @@ _C_Record :: c_struct {
 	value c_int
 }
 
-hide local_foreign c_func() i32 {
+@hide local_foreign c_func() i32 {
 	return 1
 }
 
-hide Local_C_Record :: c_struct {
+@hide Local_C_Record :: c_struct {
 	value c_int
 }
 
+@hide:file
+file_helper func() i32 {
+	return 1
+}
+
+@hide:file File_Thing :: struct {
+	value i32
+}
+
+@hide:file file_value :: 1
+
 from_a func() i32 {
 	record Local_C_Record := Local_C_Record { value = 0 }
-	return helper() + local_foreign() + i32(record.value)
+	thing File_Thing := File_Thing { value = file_value }
+	return helper() + local_foreign() + file_helper() + thing.value + i32(record.value)
 }

examples/packages/hidden_valid/app/b.bro

@@ -5,9 +5,21 @@ Box :: struct {
 	_value i32
 }
 
+@hide:file file_helper func() i32 {
+	return 2
+}
+
+@hide:file File_Thing :: struct {
+	value i32
+}
+
+@hide:file file_value :: 2
+
 from_b func(_input i32) i32 {
 	_local Box := Box { _value = _input }
 	record _C_Record := _C_Record { value = 0 }
 	thing Thing := Thing { value = value }
-	return helper() + thing.value + _local._value + _foreign() + i32(record.value) + dep._visible()
+	file_thing File_Thing := File_Thing { value = file_value }
+	return helper() + thing.value + _local._value + _foreign() + i32(record.value) +
+	       dep._visible() + file_helper() + file_thing.value
 }

examples/programs/arraylist/main.bro

@@ -19,23 +19,23 @@ init func(allocator mem.Allocator) State {
 	}
 }
 
-hide fail_alloc func(_ ?@mut anyopaque, _ usize, _ usize) ?*mut u8 {
+@hide fail_alloc func(_ ?@mut anyopaque, _ usize, _ usize) ?*mut u8 {
 	return null
 }
 
-hide fail_realloc func(_ ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize, _ usize) ?*mut u8 {
+@hide fail_realloc func(_ ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize, _ usize) ?*mut u8 {
 	return null
 }
 
-hide fail_free func(_ ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize) void {}
+@hide fail_free func(_ ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize) void {}
 
-hide fail_vtable mem.AllocatorVTable :: mem.AllocatorVTable {
+@hide fail_vtable mem.AllocatorVTable :: mem.AllocatorVTable {
 	alloc = fail_alloc,
 	realloc = fail_realloc,
 	free = fail_free,
 }
 
-hide fail_allocator mem.Allocator :: mem.Allocator {
+@hide fail_allocator mem.Allocator :: mem.Allocator {
 	context = null,
 	vtable = &fail_vtable,
 }

examples/programs/distinct_types/main.bro

@@ -82,8 +82,8 @@ main func() i32 {
 	if bits != 255 { return 10 }
 
 	values [10]u8 := [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
-	if values[LocalID(4)] != 4 { return 11 }
-	section []u8 := values[LocalID(2)..LocalID(5)]
+	if values[usize(LocalID(4))] != 4 { return 11 }
+	section []u8 := values[usize(LocalID(2))..usize(LocalID(5))]
 	if section.len != 3 or section[usize(0)] != 2 or section[usize(2)] != 4 { return 12 }
 
 	if u32(id) != 7 or usize(id) != 7 or f64(id) != 7.0 { return 13 }

examples/programs/index_unsigned_error/main.bro

@@ -1,6 +1,6 @@
 main func() i32 {
 	items [3]mut i32 := undefined
-	i int := 1
+	i u32 := 1
 	items[i] = 42
 	return 0
 }

examples/programs/io/main.bro

@@ -1,7 +1,7 @@
 io :: import "@std/io"
 process :: import "@std/process"
 
-hide read_ok func(_ ?@mut anyopaque, _ io.Handle, buffer []mut u8) usize ! io.ReadError {
+@hide read_ok func(_ ?@mut anyopaque, _ io.Handle, buffer []mut u8) usize ! io.ReadError {
 	if buffer.len == 0 {
 		return 0
 	}
@@ -13,26 +13,26 @@ hide read_ok func(_ ?@mut anyopaque, _ io.Handle, buffer []mut u8) usize ! io.Re
 	return 2
 }
 
-hide read_too_much func(_ ?@mut anyopaque, _ io.Handle, buffer []mut u8) usize ! io.ReadError {
+@hide read_too_much func(_ ?@mut anyopaque, _ io.Handle, buffer []mut u8) usize ! io.ReadError {
 	return buffer.len + 1
 }
 
-hide read_eof func(_ ?@mut anyopaque, _ io.Handle, _ []mut u8) usize ! io.ReadError {
+@hide read_eof func(_ ?@mut anyopaque, _ io.Handle, _ []mut u8) usize ! io.ReadError {
 	return 0
 }
 
-hide write_short func(_ ?@mut anyopaque, _ io.Handle, bytes []u8) usize ! io.WriteError {
+@hide write_short func(_ ?@mut anyopaque, _ io.Handle, bytes []u8) usize ! io.WriteError {
 	if bytes.len > 2 {
 		return 2
 	}
 	return bytes.len
 }
 
-hide write_none func(_ ?@mut anyopaque, _ io.Handle, _ []u8) usize ! io.WriteError {
+@hide write_none func(_ ?@mut anyopaque, _ io.Handle, _ []u8) usize ! io.WriteError {
 	return 0
 }
 
-hide write_too_much func(_ ?@mut anyopaque, _ io.Handle, bytes []u8) usize ! io.WriteError {
+@hide write_too_much func(_ ?@mut anyopaque, _ io.Handle, bytes []u8) usize ! io.WriteError {
 	return bytes.len + 1
 }
 

examples/programs/mem_allocator/typed_alloc.bro

@@ -1,27 +1,27 @@
 mem :: import "@std/mem"
 
-hide probe_count func(context ?@mut anyopaque) void {
+@hide probe_count func(context ?@mut anyopaque) void {
 	if context |raw| {
 		count @mut usize :: ptrcast!(usize, raw)
 		count^ += 1
 	}
 }
 
-hide probe_alloc func(context ?@mut anyopaque, _ usize, _ usize) ?*mut u8 {
+@hide probe_alloc func(context ?@mut anyopaque, _ usize, _ usize) ?*mut u8 {
 	probe_count(context)
 	return null
 }
 
-hide probe_realloc func(context ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize, _ usize) ?*mut u8 {
+@hide probe_realloc func(context ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize, _ usize) ?*mut u8 {
 	probe_count(context)
 	return null
 }
 
-hide probe_free func(context ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize) void {
+@hide probe_free func(context ?@mut anyopaque, _ ?*mut u8, _ usize, _ usize) void {
 	probe_count(context)
 }
 
-hide probe_vtable mem.AllocatorVTable :: mem.AllocatorVTable {
+@hide probe_vtable mem.AllocatorVTable :: mem.AllocatorVTable {
 	alloc = probe_alloc,
 	realloc = probe_realloc,
 	free = probe_free,

examples/programs/milestone_24/main.bro

@@ -52,7 +52,7 @@ main func() i32 {
 	items[0] = 10
 	items[1] = 20
 
-	idx u8 := 2
+	idx usize := 2
 	items[idx] = items[0] + items[1]
 	if (items[2] != 30) return 1
 

std/debug/debug.hon

@@ -10,7 +10,7 @@ print func($format []u8, $Args type, args Args) void {
 	io.print(writer, format, Args, args) catch |_| {}
 }
 
-hide write func(_ ?@mut anyopaque, handle io.Handle, bytes []u8) usize ! io.WriteError {
+@hide write func(_ ?@mut anyopaque, handle io.Handle, bytes []u8) usize ! io.WriteError {
 	request usize := bytes.len
 	maximum usize :: usize(maxval!(c_long))
 	if request > maximum {

std/hashmap/hashmap.hon

@@ -134,7 +134,7 @@ put func(
 	}
 }
 
-hide normalize func(hash usize) usize {
+@hide normalize func(hash usize) usize {
 	# mapping both 0 and 1 to 1 is safe because equality resolves
 	# collisions (since hash and key must both be equal).
 	if (hash == 0) return 1
@@ -143,7 +143,7 @@ hide normalize func(hash usize) usize {
 
 #! FNV-1a hash implementation.
 #! note: vulnerable to collision attacks.
-hide str_hash func(key []u8) usize {
+@hide str_hash func(key []u8) usize {
 	hash u32 := 2166136261 # offset basis
 	prime u32 := 16777619
 
@@ -155,6 +155,6 @@ hide str_hash func(key []u8) usize {
 	return usize(hash)
 }
 
-hide str_eql func(a, b []u8) bool {
+@hide str_eql func(a, b []u8) bool {
 	return mem.eql(a, b)
 }

std/io/file.hon

@@ -46,7 +46,7 @@ writer func(file File) Writer {
 	}
 }
 
-hide system_read func(_ ?@mut anyopaque, handle Handle, buffer []mut u8) usize ! ReadError {
+@hide system_read func(_ ?@mut anyopaque, handle Handle, buffer []mut u8) usize ! ReadError {
 	request usize := buffer.len
 	maximum usize :: usize(maxval!(c_long))
 	if request > maximum {
@@ -68,7 +68,7 @@ hide system_read func(_ ?@mut anyopaque, handle Handle, buffer []mut u8) usize !
 	}
 }
 
-hide system_write func(_ ?@mut anyopaque, handle Handle, bytes []u8) usize ! WriteError {
+@hide system_write func(_ ?@mut anyopaque, handle Handle, bytes []u8) usize ! WriteError {
 	request usize := bytes.len
 	maximum usize :: usize(maxval!(c_long))
 	if request > maximum {
@@ -90,7 +90,7 @@ hide system_write func(_ ?@mut anyopaque, handle Handle, bytes []u8) usize ! Wri
 	}
 }
 
-hide system_open func(_ ?@mut anyopaque, path [;0]u8, mode FileMode) Handle ! OpenError {
+@hide system_open func(_ ?@mut anyopaque, path [;0]u8, mode FileMode) Handle ! OpenError {
 	flags c_int := c.O_RDONLY
 	match mode {
 		.read_only: flags = c.O_RDONLY
@@ -108,25 +108,25 @@ hide system_open func(_ ?@mut anyopaque, path [;0]u8, mode FileMode) Handle ! Op
 	}
 }
 
-hide system_close func(_ ?@mut anyopaque, handle Handle) void ! CloseError {
+@hide system_close func(_ ?@mut anyopaque, handle Handle) void ! CloseError {
 	if c.close(handle.file_desc) != 0 {
 		return .close_failed
 	}
 }
 
-hide system_stdin func(_ ?@mut anyopaque) Handle {
+@hide system_stdin func(_ ?@mut anyopaque) Handle {
 	return Handle {file_desc = c_int(Stream.stdin)}
 }
 
-hide system_stdout func(_ ?@mut anyopaque) Handle {
+@hide system_stdout func(_ ?@mut anyopaque) Handle {
 	return Handle {file_desc = c_int(Stream.stdout)}
 }
 
-hide system_stderr func(_ ?@mut anyopaque) Handle {
+@hide system_stderr func(_ ?@mut anyopaque) Handle {
 	return Handle {file_desc = c_int(Stream.stderr)}
 }
 
-hide system_vtable IoVTable :: IoVTable {
+@hide system_vtable IoVTable :: IoVTable {
 	read = system_read,
 	write = system_write,
 	open = system_open,
@@ -136,7 +136,7 @@ hide system_vtable IoVTable :: IoVTable {
 	stderr = system_stderr,
 }
 
-hide system func() Io {
+@hide system func() Io {
 	return Io {
 		context = null,
 		vtable = &system_vtable,

std/io/io.hon

@@ -128,7 +128,7 @@ print func(output Writer, $format []u8, $Args type, args Args) void ! WriteError
 	}
 }
 
-hide write_integer_signed func(output Writer, value i64, base u64, uppercase bool) void ! WriteError {
+@hide write_integer_signed func(output Writer, value i64, base u64, uppercase bool) void ! WriteError {
 	buffer [65]mut u8 := undefined
 	end usize := buffer.len
 	current i64 := value
@@ -161,7 +161,7 @@ hide write_integer_signed func(output Writer, value i64, base u64, uppercase boo
 	return
 }
 
-hide write_integer_unsigned func(output Writer, value u64, base u64, uppercase bool) void ! WriteError {
+@hide write_integer_unsigned func(output Writer, value u64, base u64, uppercase bool) void ! WriteError {
 	buffer [65]mut u8 := undefined
 	end usize := buffer.len
 	current u64 := value
@@ -184,7 +184,7 @@ hide write_integer_unsigned func(output Writer, value u64, base u64, uppercase b
 	return
 }
 
-hide FormatTokenKind :: enum {
+@hide FormatTokenKind :: enum {
 	unused
 	literal
 	default
@@ -198,14 +198,14 @@ hide FormatTokenKind :: enum {
 	scientific
 }
 
-hide FormatToken :: struct {
+@hide FormatToken :: struct {
 	kind FormatTokenKind
 	start usize
 	end usize
 	field []u8
 }
 
-hide parse_format func($N usize, $format []u8, $Args type) [N]mut FormatToken {
+@hide parse_format func($N usize, $format []u8, $Args type) [N]mut FormatToken {
 	tokens [N]mut FormatToken := undefined
 	for (usize(0))..format.len |index| {
 		tokens[index] = FormatToken {kind = .unused, start = 0, end = 0, field = ""}
@@ -310,17 +310,17 @@ hide parse_format func($N usize, $format []u8, $Args type) [N]mut FormatToken {
 	return tokens
 }
 
-hide format_field_name func($T type, index usize) []u8 {
+@hide format_field_name func($T type, index usize) []u8 {
 	match typeinfo!(T) {
 		.record |record|: return record.fields[index].name
 		else: compile_error!("io.print arguments must be a tuple")
 	}
 }
-hide distinct_value func($Backing, $Distinct type, value Distinct) Backing {
+@hide distinct_value func($Backing, $Distinct type, value Distinct) Backing {
 	return ptrcast!(Backing, &value)^
 }
 
-hide scalar_or_distinct_type func($T type) bool {
+@hide scalar_or_distinct_type func($T type) bool {
 	match typeinfo!(T) {
 		.bool: return true
 		.integer: return true
@@ -332,7 +332,7 @@ hide scalar_or_distinct_type func($T type) bool {
 
 
 
-hide write_integer func(output Writer, $T type, value T, base u64, uppercase bool) void ! WriteError {
+@hide write_integer func(output Writer, $T type, value T, base u64, uppercase bool) void ! WriteError {
 	match typeinfo!(T) {
 		.integer: if minval!(T) < 0 {
 			try write_integer_signed(output, i64(value), base, uppercase)
@@ -350,7 +350,7 @@ hide write_integer func(output Writer, $T type, value T, base u64, uppercase boo
 }
 
 # note: libc keeps float formatting small; replace it with a native shortest-roundtrip writer if locale independence matters.
-hide write_float func(output Writer, $T type, value T, scientific bool) void ! WriteError {
+@hide write_float func(output Writer, $T type, value T, scientific bool) void ! WriteError {
 	match typeinfo!(T) {
 		.float: {
 			buffer [64]mut u8 := undefined
@@ -381,7 +381,7 @@ hide write_float func(output Writer, $T type, value T, scientific bool) void ! W
 	return
 }
 
-hide write_decimal func(output Writer, $T type, value T) void ! WriteError {
+@hide write_decimal func(output Writer, $T type, value T) void ! WriteError {
 	match typeinfo!(T) {
 		.integer: try write_integer(output, value, 10, false)
 		.float: try write_float(output, value, false)
@@ -395,7 +395,7 @@ hide write_decimal func(output Writer, $T type, value T) void ! WriteError {
 	return
 }
 
-hide write_character func(output Writer, $T type, value T) void ! WriteError {
+@hide write_character func(output Writer, $T type, value T) void ! WriteError {
 	match typeinfo!(T) {
 		.integer: {
 			if minval!(T) < 0 or maxval!(T) > 255 {
@@ -414,7 +414,7 @@ hide write_character func(output Writer, $T type, value T) void ! WriteError {
 	return
 }
 
-hide write_default func(output Writer, $T type, value T) void ! WriteError {
+@hide write_default func(output Writer, $T type, value T) void ! WriteError {
 	match typeinfo!(T) {
 		.bool: if value {
 			try write_all(output, "true")

std/mem/mem.hon

@@ -119,11 +119,11 @@ empty func($T type) []mut T {
 	return empty_slice(T, 0)
 }
 
-hide empty_storage [1]mut u64 := [0]
+@hide empty_storage [1]mut u64 := [0]
 
-hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
+@hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
 
-hide power_of_two func(value usize) bool {
+@hide power_of_two func(value usize) bool {
 	if (value == 0) return false
 	current usize := value
 	while current > 1 {
@@ -134,7 +134,7 @@ hide power_of_two func(value usize) bool {
 	return true
 }
 
-hide c_alloc func(_ ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
+@hide c_alloc func(_ ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	if (power_of_two(alignment) == false) return null
 
 	if alignment <= malloc_alignment {
@@ -148,7 +148,7 @@ hide c_alloc func(_ ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	return ptrcast!(u8, memory[0])
 }
 
-hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
+@hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
 	if (power_of_two(alignment) == false) return null
 
 	if new_size == 0 {
@@ -174,11 +174,11 @@ hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size
 	return c_alloc(null, new_size, alignment)
 }
 
-hide c_free func(_ ?@mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
+@hide c_free func(_ ?@mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
 	c.free(memory)
 }
 
-hide c_vtable AllocatorVTable :: AllocatorVTable {
+@hide c_vtable AllocatorVTable :: AllocatorVTable {
 	alloc = c_alloc,
 	realloc = c_realloc,
 	free = c_free,

std/meta/meta.test.hon

@@ -13,13 +13,13 @@ TestOuter :: distinct TestInner
 TestOuterAlias :: alias TestOuter
 
 
-hide array_info_matches func($Array, $Child type, $len usize) bool {
+@hide array_info_matches func($Array, $Child type, $len usize) bool {
 	match typeinfo!(Array) {
 		.array |info|: return info.child == Child and info.len == len
 		else: return false
 	}
 }
-hide distinct_info_matches func($Distinct, $Backing type) bool {
+@hide distinct_info_matches func($Distinct, $Backing type) bool {
 	match typeinfo!(Distinct) {
 		.distinct |backing|: return backing == Backing
 		else: return false

std/static_string_map/static_string_map.hon

@@ -10,7 +10,7 @@ StaticStringMap func($V type) type {
 	}
 }
 
-hide Pair func($V type) type {
+@hide Pair func($V type) type {
 	return struct { []u8, V }
 }
 

std/testing/testing.hon

@@ -73,10 +73,10 @@ expect_type func($Expected, $Actual type, _ Actual, location SourceLocation) voi
 
 run func(name []u8, callback *func() void ! Error) bool {
 	callback() catch |_| {
-		debug.print("{s}...[failed]\n", {name,})
+		debug.print("{s}...[\x1b[91mfailure\x1b[0m]\n", {name,})
 		return false
 	}
-	debug.print("{s}...[ok]\n", {name,})
+	debug.print("{s}...[\x1b[92mok\x1b[0m]\n", {name,})
 	return true
 }
 

testbed/lexer/main.bro

@@ -20,17 +20,17 @@ Token :: struct {
 	kind Kind
 }
 
-hide is_alpha func(value u8) bool {
+@hide is_alpha func(value u8) bool {
 	return value == '_' or
 	       value >= 'a' and value <= 'z' or
 	       value >= 'A' and value <= 'Z'
 }
 
-hide is_digit func(value u8) bool {
+@hide is_digit func(value u8) bool {
 	return value >= '0' and value <= '9'
 }
 
-hide word_kind func(word []u8) Kind {
+@hide word_kind func(word []u8) Kind {
 	# ponytail: enough keywords for the demo; add the full language set when a parser needs it.
 	if mem.eql(word, "func") or mem.eql(word, "void") {
 		return .keyword
@@ -38,7 +38,7 @@ hide word_kind func(word []u8) Kind {
 	return .identifier
 }
 
-hide append_token func(tokens @mut std.ArrayList(Token), kind Kind, start, end usize) void ! mem.AllocError {
+@hide append_token func(tokens @mut std.ArrayList(Token), kind Kind, start, end usize) void ! mem.AllocError {
 	try arraylist.append(tokens, Token {
 		start = start,
 		length = end - start,
@@ -95,7 +95,7 @@ lex func(source []u8, tokens @mut std.ArrayList(Token)) void ! mem.AllocError {
 	return
 }
 
-hide kind_name func(kind Kind) *c_char {
+@hide kind_name func(kind Kind) *c_char {
 	return match kind {
 		.invalid: "invalid"
 		.eof: "eof"
@@ -108,7 +108,7 @@ hide kind_name func(kind Kind) *c_char {
 	}
 }
 
-hide print_token func(source []u8, token Token) void {
+@hide print_token func(source []u8, token Token) void {
 	_ = c.printf("%-11s", kind_name(token.kind))
 	if token.length != 0 {
 		_ = c.printf(" `")

testbed/lexer/std/io/io.bro

@@ -74,7 +74,7 @@ write_all func(writer Writer, bytes []u8) void ! WriteError {
 	return
 }
 
-hide system_read func(_ ?*mut anyopaque, stream ReadStream, buffer []mut u8) usize ! ReadError {
+@hide system_read func(_ ?*mut anyopaque, stream ReadStream, buffer []mut u8) usize ! ReadError {
 	request usize := buffer.len
 	maximum usize :: usize(maxval!(c_long))
 	if request > maximum {
@@ -91,7 +91,7 @@ hide system_read func(_ ?*mut anyopaque, stream ReadStream, buffer []mut u8) usi
 	}
 }
 
-hide system_write func(_ ?*mut anyopaque, stream WriteStream, bytes []u8) usize ! WriteError {
+@hide system_write func(_ ?*mut anyopaque, stream WriteStream, bytes []u8) usize ! WriteError {
 	fd c_int :: c_int(stream)
 	request usize := bytes.len
 	maximum usize :: usize(maxval!(c_long))
@@ -109,12 +109,12 @@ hide system_write func(_ ?*mut anyopaque, stream WriteStream, bytes []u8) usize
 	}
 }
 
-hide system_vtable IoVTable :: IoVTable {
+@hide system_vtable IoVTable :: IoVTable {
 	read = system_read,
 	write = system_write,
 }
 
-hide system func() Io {
+@hide system func() Io {
 	return Io {
 		context = null,
 		vtable = &system_vtable,

testbed/lexer/std/mem/mem.bro

@@ -41,9 +41,9 @@ eql func($T type, left, right []T) bool {
 	return true
 }
 
-hide empty_storage [1]mut u64 := [0]
+@hide empty_storage [1]mut u64 := [0]
 
-hide empty_slice func($T type, count usize) []mut T {
+@hide empty_slice func($T type, count usize) []mut T {
 	pointer *mut T :: ptrcast!(T, (&empty_storage).ptr)
 	return pointer[..count]
 }
@@ -116,9 +116,9 @@ free func($T type, allocator Allocator, memory []mut T) void {
 	}
 }
 
-hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
+@hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
 
-hide power_of_two func(value usize) bool {
+@hide power_of_two func(value usize) bool {
 	if value == 0 {
 		return false
 	}
@@ -135,7 +135,7 @@ hide power_of_two func(value usize) bool {
 	return true
 }
 
-hide c_alloc func(_ ?*mut anyopaque, size usize, alignment usize) ?*mut u8 {
+@hide c_alloc func(_ ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	if power_of_two(alignment) == false {
 		return null
 	}
@@ -153,7 +153,7 @@ hide c_alloc func(_ ?*mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	return ptrcast!(u8, memory[0])
 }
 
-hide c_realloc func(_ ?*mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
+@hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
 	if power_of_two(alignment) == false {
 		return null
 	}
@@ -186,11 +186,11 @@ hide c_realloc func(_ ?*mut anyopaque, memory ?*mut u8, old_size usize, new_size
 	return c_alloc(null, new_size, alignment)
 }
 
-hide c_free func(_ ?*mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
+@hide c_free func(_ ?@mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
 	c.free(memory)
 }
 
-hide c_vtable AllocatorVTable :: AllocatorVTable {
+@hide c_vtable AllocatorVTable :: AllocatorVTable {
 	alloc = c_alloc,
 	realloc = c_realloc,
 	free = c_free,

testbed/mem_alloc/std/mem/mem.bro

@@ -27,9 +27,9 @@ raw_free func(allocator Allocator, memory ?*mut u8, size usize, alignment usize)
 	allocator.vtable.free(allocator.context, memory, size, alignment)
 }
 
-hide empty_storage [1]mut u64 := [0]
+@hide empty_storage [1]mut u64 := [0]
 
-hide empty_slice func($T type, count usize) []mut T {
+@hide empty_slice func($T type, count usize) []mut T {
 	pointer *mut T :: ptrcast!(T, (&empty_storage).ptr)
 	return pointer[..count]
 }
@@ -61,9 +61,9 @@ free func($T type, allocator Allocator, memory []mut T) void {
 	}
 }
 
-hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
+@hide malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
 
-hide power_of_two func(value usize) bool {
+@hide power_of_two func(value usize) bool {
 	if value == 0 {
 		return false
 	}
@@ -80,7 +80,7 @@ hide power_of_two func(value usize) bool {
 	return true
 }
 
-hide c_alloc func(_ ?*mut anyopaque, size usize, alignment usize) ?*mut u8 {
+@hide c_alloc func(_ ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	if power_of_two(alignment) == false {
 		return null
 	}
@@ -98,7 +98,7 @@ hide c_alloc func(_ ?*mut anyopaque, size usize, alignment usize) ?*mut u8 {
 	return ptrcast!(u8, memory[0])
 }
 
-hide c_realloc func(_ ?*mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
+@hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
 	if power_of_two(alignment) == false {
 		return null
 	}
@@ -131,11 +131,11 @@ hide c_realloc func(_ ?*mut anyopaque, memory ?*mut u8, old_size usize, new_size
 	return c_alloc(null, new_size, alignment)
 }
 
-hide c_free func(_ ?*mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
+@hide c_free func(_ ?@mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
 	c.free(memory)
 }
 
-hide c_vtable AllocatorVTable :: AllocatorVTable {
+@hide c_vtable AllocatorVTable :: AllocatorVTable {
 	alloc = c_alloc,
 	realloc = c_realloc,
 	free = c_free,