fix optional-presence comparison

compiler/checker/checker.odin

@@ -2730,8 +2730,9 @@ infer_call_comptime_values :: proc(
 	for value_bound in bound {
 		all_bound = all_bound && value_bound
 	}
-	// Concrete arguments bind first. Numeric constants are contextual and therefore
+	// Concrete arguments bind first. Numeric constants and `none` are contextual and
-	// only contribute their default type after stronger evidence has had a chance.
+	// therefore only contribute after stronger evidence has had a chance to bind the
+	// parameter type.
 	weak_passes := [2]bool{false, true}
 	for weak in weak_passes {
 		for arg_id, source_index in args {
@@ -2742,7 +2743,9 @@ infer_call_comptime_values :: proc(
 			if param_index < 0 || function.params[param_index].comptime_value {
 				continue
 			}
-			is_weak := is_numeric_constant_expr(checker, arg_id)
+			arg_expr := checker.ast_module.exprs[arg_id]
+			is_none := arg_expr.kind == .None
+			is_weak := is_numeric_constant_expr(checker, arg_id) || is_none
 			if is_weak != weak {
 				continue
 			}
@@ -2753,7 +2756,6 @@ infer_call_comptime_values :: proc(
 			// keyed record must be checked against the specialized parameter type.
 			// Its provisional structural type intentionally contains only the supplied
 			// fields, so comparing that type here would reject omitted defaulted fields.
-			arg_expr := checker.ast_module.exprs[arg_id]
 			if all_bound && arg_expr.kind == .Struct_Literal && !arg_expr.tuple && !symbol.is_valid(arg_expr.name) {
 				continue
 			}
@@ -2766,9 +2768,22 @@ infer_call_comptime_values :: proc(
 					}
 				}
 			}
+			actual := actual_args[param_index]
+			if is_none {
+				previous := checker.current_comptime_values
+				checker.current_comptime_values = values
+				contextual := type_from_syntax(
+					checker, function.params[param_index].type, function.pkg, function.file,
+				)
+				checker.current_comptime_values = previous
+				if types.is_optional(contextual, &checker.module.types) {
+					actual = contextual
+					actual_args[param_index] = contextual
+				}
+			}
 			matched = match_inferred_type_pattern(
 				checker, function, prefix, function.params[param_index].type,
-				actual_args[param_index], values, bound,
+				actual, values, bound,
 				checker.ast_module.exprs[arg_id].span, diagnose,
 			) && matched
 		}
@@ -4482,8 +4497,18 @@ infer_compound_expr :: proc(
 		right := infer_nested_expr(checker, expr.right, locals, pkg, file, demanded, local_types, types.U64)
 		return left if types.is_concrete_integer(left) && types.is_unsigned(right, checker.target) else types.INVALID
 	case .Eq, .Ne, .Lt, .Le, .Gt, .Ge, .And, .Or:
+		left_expr := checker.ast_module.exprs[expr.left]
+		right_expr := checker.ast_module.exprs[expr.right]
+		if left_expr.kind == .None && right_expr.kind != .None {
+			right := infer_nested_expr(checker, expr.right, locals, pkg, file, demanded, local_types)
+			_ = infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types, right)
+		} else if right_expr.kind == .None && left_expr.kind != .None {
+			left := infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types)
+			_ = infer_nested_expr(checker, expr.right, locals, pkg, file, demanded, local_types, left)
+		} else {
 			_ = infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types)
 			_ = infer_nested_expr(checker, expr.right, locals, pkg, file, demanded, local_types)
+		}
 		return types.BOOL
 	case .Range:
 		left := infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types)
@@ -4519,7 +4544,7 @@ infer_compound_expr :: proc(
 		}
 		return types.array(store, element, u64(len(expr.args)), false)
 	case .None:
-		return types.INVALID
+		return expected if types.is_optional(expected, store) else types.INVALID
 	case .Undefined:
 		return types.INVALID
 	case .Enum_Literal:
@@ -8124,8 +8149,9 @@ build_compound_expr :: proc(
 			left=left, right=right, target=hir.INVALID_REF, diagnostic=source.INVALID_DIAGNOSTIC,
 		})
 	case .Eq, .Ne, .Lt, .Le, .Gt, .Ge:
-		// Contextualize a bare integer-literal operand to the other operand's type
+		// Contextualize literals whose type comes from their peer. This covers
-		// so comparisons like `count > 0` or `0 < count` type-check.
+		// integer and enum literals as well as optional presence tests such as
+		// `value == none` and `none != value`.
 		left_const := eval_constant(checker, expr.left)
 		right_const := eval_constant(checker, expr.right)
 		left, right: hir.Expr_Id
@@ -8133,7 +8159,13 @@ build_compound_expr :: proc(
 		right_expr := checker.ast_module.exprs[expr.right]
 		left_numeric_const := left_const.kind == .Value || is_float_constant_expr(checker, expr.left)
 		right_numeric_const := right_const.kind == .Value || is_float_constant_expr(checker, expr.right)
-		if right_expr.kind == .Enum_Literal && left_expr.kind != .Enum_Literal {
+		if right_expr.kind == .None && left_expr.kind != .None {
+			left = build_nested_expr(checker, expr.left, locals, global_reads, calls, types.INVALID, pkg, file)
+			right = build_nested_expr(checker, expr.right, locals, global_reads, calls, checker.module.exprs[left].type, pkg, file)
+		} else if left_expr.kind == .None && right_expr.kind != .None {
+			right = build_nested_expr(checker, expr.right, locals, global_reads, calls, types.INVALID, pkg, file)
+			left = build_nested_expr(checker, expr.left, locals, global_reads, calls, checker.module.exprs[right].type, pkg, file)
+		} else if right_expr.kind == .Enum_Literal && left_expr.kind != .Enum_Literal {
 			left = build_nested_expr(checker, expr.left, locals, global_reads, calls, types.INVALID, pkg, file)
 			right = build_nested_expr(checker, expr.right, locals, global_reads, calls, checker.module.exprs[left].type, pkg, file)
 		} else if left_expr.kind == .Enum_Literal && right_expr.kind != .Enum_Literal {
@@ -8157,7 +8189,14 @@ build_compound_expr :: proc(
 		left_type := checker.module.exprs[left].type
 		right_type := checker.module.exprs[right].type
 		operand_type := types.INVALID
-		if types.is_enum(left_type, store) || types.is_enum(right_type, store) {
+		if left_expr.kind == .None || right_expr.kind == .None {
+			if expr.kind != .Eq && expr.kind != .Ne ||
+			   !types.is_optional(left_type, store) || !types.equal(left_type, right_type) {
+				id := source.add(checker.diagnostics, expr.span, "'none' only supports '==' and '!=' with an optional value")
+				return invalid_hir_expr(checker, expr.span, id, types.BOOL)
+			}
+			operand_type = left_type
+		} else if types.is_enum(left_type, store) || types.is_enum(right_type, store) {
 			if !types.equal(left_type, right_type) || (expr.kind != .Eq && expr.kind != .Ne) {
 				id := source.add(checker.diagnostics, expr.span, "enum values only support '==' and '!=' with the same enum type")
 				return invalid_hir_expr(checker, expr.span, id, types.BOOL)

compiler/checker/comptime.odin

@@ -1287,6 +1287,20 @@ ct_eval_expr :: proc(
 		   types.is_concrete_integer(expected) {
 			left_expected = expected
 		}
+		left_expr := checker.ast_module.exprs[expr.left]
+		right_expr := checker.ast_module.exprs[expr.right]
+		if left_expr.kind == .None && right_expr.kind != .None &&
+		   (expr.kind == .Eq || expr.kind == .Ne) {
+			right, right_flow, right_ok := ct_eval_expr(state, expr.right, types.INVALID, depth+1)
+			if !right_ok || right_flow.kind != .Normal {
+				return INVALID_CT_VALUE, right_flow, right_ok
+			}
+			left, flow, ok := ct_eval_expr(state, expr.left, state.values[right].type, depth+1)
+			if !ok || flow.kind != .Normal {
+				return INVALID_CT_VALUE, flow, ok
+			}
+			return ct_eval_binary(state, expr.kind, left, right, expr.span)
+		}
 		left, flow, ok := ct_eval_expr(state, expr.left, left_expected, depth+1)
 		if !ok || flow.kind != .Normal {
 			return INVALID_CT_VALUE, flow, ok
@@ -2118,6 +2132,18 @@ ct_eval_binary :: proc(state: ^Ct_State, op: ast.Expr_Kind, left_id, right_id: C
 	left := state.values[left_id]
 	right := state.values[right_id]
 	is_compare := op == .Eq || op == .Ne || op == .Lt || op == .Le || op == .Gt || op == .Ge
+	if left.kind == .None || right.kind == .None {
+		if (op != .Eq && op != .Ne) ||
+		   !types.is_optional(left.type, &state.checker.module.types) ||
+		   !types.equal(left.type, right.type) {
+			return INVALID_CT_VALUE, ct_flow(.Normal), ct_fail(state, .Not_Comptime, span, "'none' only supports '==' and '!=' with an optional value")
+		}
+		equal := left.kind == .None && right.kind == .None
+		if op == .Ne {
+			equal = !equal
+		}
+		return ct_add_value(state, Ct_Value{kind=.Bool, type=types.BOOL, integer=1 if equal else 0}), ct_flow(.Normal), true
+	}
 	if left.kind == .Type || right.kind == .Type {
 		if left.kind != .Type || right.kind != .Type || (op != .Eq && op != .Ne) {
 			return INVALID_CT_VALUE, ct_flow(.Normal), ct_fail(state, .Not_Comptime, span, "type values only support '==' and '!=' with another type")

compiler/lower/lower.odin

@@ -561,6 +561,25 @@ lower_compound_expr :: proc(state: ^State, expr_id: hir.Expr_Id) -> ir.Instructi
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
 	case .Eq, .Ne, .Lt, .Le, .Gt, .Ge:
+		left_expr := state.hir_module.exprs[expr.left]
+		right_expr := state.hir_module.exprs[expr.right]
+		if left_expr.kind == .None || right_expr.kind == .None {
+			optional_expr := expr.right if left_expr.kind == .None else expr.left
+			optional := lower_nested_expr(state, optional_expr)
+			present := append_instruction(state, ir.Instruction{
+				op=.Optional_Is_Some, span=expr.span, type=types.BOOL,
+				target=ir.INVALID_REF, a=optional, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+			if expr.kind == .Ne {
+				return present
+			}
+			return append_instruction(state, ir.Instruction{
+				op=.Not, span=expr.span, type=types.BOOL,
+				target=ir.INVALID_REF, a=present, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		}
 		left := lower_nested_expr(state, expr.left)
 		right := lower_nested_expr(state, expr.right)
 		predicate := ir.Compare_Predicate.Eq

compiler_tests.odin

@@ -13822,6 +13822,7 @@ enum_field_struct_and_contextual_anonymous_records_compile_and_run :: proc(t: ^t
 	main_path := "/tmp/brolang-test-enum-field-struct/main.bro"
 	output := "/tmp/brolang-test-enum-field-struct-output"
 	text := `meta :: import "@std/meta"
+testing :: import "@std/testing"
 
 TokenKind :: enum(u8) {
 	ident = 3
@@ -13854,6 +13855,8 @@ Generated func($T type) type {
 
 GeneratedInt :: alias Generated(i32)
 ordered Names = {}
+static_none ?i32 :: none
+static_some ?i32 :: 1
 
 Map func($E, $V type) type {
 	match typeinfo!(E) {
@@ -13894,6 +13897,8 @@ get func($E, $V type, map @Map(E, V), key E) ?V {
 
 main func() i32 {
 	_ = ordered
+	if !$(static_none == none) or !$(none == static_none) or
+	   $(static_some == none) or $(none == static_some) { return 23 }
 	inferred :: {x = 40, name = "bro"}
 	if inferred.x != 40 or inferred.name.len != 3 { return 1 }
 	direct Direct = {x = 7}
@@ -13937,10 +13942,17 @@ main func() i32 {
 	})
 	if !map.present[0] or !map.present[1] or map.present[2] { return 9 }
 	if map.values[0].len != 10 or map.values[1].len != 7 { return 18 }
-	if get(TokenKind, []u8, &map, TokenKind.ident) |value| {
+	ident :: get(TokenKind, []u8, &map, TokenKind.ident)
+	if ident == none or none == ident { return 19 }
+	if ident |value| {
 		if value.len != 10 { return 19 }
 	} else { return 20 }
-	if get(TokenKind, []u8, &map, TokenKind.eof) |_| { return 21 }
+	eof :: get(TokenKind, []u8, &map, TokenKind.eof)
+	if eof != none or none != eof { return 21 }
+	location testing.SourceLocation = {file = "test.bro", line = 1, column = 1}
+	testing.expect_equal(none, eof, location) catch |_| { return 24 }
+	testing.expect_equal(ident, ident, location) catch |_| { return 25 }
+	if eof |_| { return 22 }
 	return 0
 }
 `

std/testing/testing.bro

@@ -1,4 +1,5 @@
 import "@std/debug"
+import "@std/mem"
 
 Error :: enum {
 	expectation_failed
@@ -18,11 +19,35 @@ expect func(condition bool, location SourceLocation) void ! Error {
 }
 
 expect_equal func($T type, expected, actual T, location SourceLocation) void ! Error {
+	match typeinfo!(T) {
+		.optional: {
+			if expected |expected_value| {
+				if actual |actual_value| {
+					try expect_equal(expected_value, actual_value, location)
+					return
+				}
+				debug.print("{s}:{d}:{d}: expected an optional value, found none\n", {location.file, location.line, location.column})
+				return .expectation_failed
+			}
+			if actual |_| {
+				debug.print("{s}:{d}:{d}: expected none, found an optional value\n", {location.file, location.line, location.column})
+				return .expectation_failed
+			}
+		}
+		.slice: {
+			if !mem.eql(expected, actual) {
+				debug.print("{s}:{d}:{d}: expected and actual slices differ\n", {location.file, location.line, location.column})
+				return .expectation_failed
+			}
+		}
+		else: {
 			if expected != actual {
 				debug.print("{s}:{d}:{d}: expected {}, found {}\n", {location.file, location.line, location.column, expected, actual})
 				return .expectation_failed
 			}
 		}
+	}
+}
 
 expect_type func($Expected, $Actual type, _ Actual, location SourceLocation) void ! Error {
 	try expect($(Expected == Actual), location)