scalar family constraints for struct fields

LANGUAGE.md

@@ -39,6 +39,20 @@ roadmap and milestone history.
 - native sum composition with `A | B` for unbacked enums and tagged unions, using program-global `u16` variant ids
 - fallible channel types `T ! E`, where `E` is a native enum/tagged union or supported sum composition
 
+#### native record constraint fields
+
+A direct `int`, `float`, or `range` field in a named native struct or union is a
+program-wide constraint, not per-value polymorphism. Before record layout, all reachable keyed
+constructors, field assignments, and concrete uses of field reads contribute demands and the field
+resolves once to one concrete runtime type. Compatible scalar demands widen normally. Integer
+literals remain provisional until inference settles, so a later `usize` use can resolve an `int`
+field to `usize`; otherwise literal-only `int` fields use the widest smallest-signed type required,
+and literal-only `float` fields use `f64`.
+
+An undemanded field or incompatible demands are errors. This inference applies only to direct
+fields of named native records. `c_struct` fields, nested constraints such as `[]int`, and fields in
+anonymous generated records still require concrete runtime types.
+
 #### keyword member names
 
 Reserved keywords are valid native enum members and tagged-union variants when used in an

compiler/checker/checker.odin

@@ -174,6 +174,14 @@ Checker :: struct {
 	global_open_float:    []bool,
 	global_const_value:   []i128,
 	global_demands_dirty: bool,
+	// Program-wide inference for direct constraint fields in named native records.
+	// The arrays use Store.fields' existing dense indices; resolved concrete types
+	// live directly in module.types.fields so layout and lowering need no side table.
+	record_field_constraints: []types.Type,
+	record_field_defaults:    []types.Type,
+	record_field_conflicts:   []types.Type,
+	record_field_conflict_spans: []source.Span,
+	record_field_demands_dirty: bool,
 	external_global_canonical: []ast.Global_Id,
 	external_global_diagnostics: []source.Diagnostic_Id,
 	constants:            []Constant,
@@ -2399,6 +2407,211 @@ validate_declarations :: proc(checker: ^Checker) {
 	}
 }
 
+init_record_field_inference :: proc(checker: ^Checker) {
+	store := &checker.module.types
+	for item in store.nodes {
+		if !(item.declared && (item.kind == .Struct || item.kind == .Union) &&
+		     !item.c_layout && symbol.is_valid(symbol.Id(item.name))) {
+			continue
+		}
+		start := int(item.field_start)
+		end := start+int(item.field_count)
+		if start < 0 || end > len(store.fields) {
+			continue
+		}
+		for slot in start..<end {
+			if types.is_constraint(store.fields[slot].type) {
+				checker.record_field_constraints[slot] = store.fields[slot].type
+			}
+		}
+	}
+}
+
+is_inferred_record_field :: proc(checker: ^Checker, slot: int) -> bool {
+	return slot >= 0 && slot < len(checker.record_field_constraints) &&
+	       types.is_constraint(checker.record_field_constraints[slot])
+}
+
+record_field_owner :: proc(checker: ^Checker, slot: int) -> (symbol.Id, symbol.Id, bool) {
+	for item in checker.module.types.nodes {
+		if !(item.declared && (item.kind == .Struct || item.kind == .Union) &&
+		     !item.c_layout && symbol.is_valid(symbol.Id(item.name))) {
+			continue
+		}
+		start := int(item.field_start)
+		if slot >= start && slot < start+int(item.field_count) &&
+		   slot >= 0 && slot < len(checker.module.types.fields) {
+			return symbol.Id(item.name), symbol.Id(checker.module.types.fields[slot].name), true
+		}
+	}
+	return symbol.INVALID, symbol.INVALID, false
+}
+
+record_field_conflict :: proc(checker: ^Checker, slot: int, actual: types.Type, span: source.Span) {
+	if !is_inferred_record_field(checker, slot) ||
+	   types.is_valid(checker.record_field_conflicts[slot]) {
+		return
+	}
+	checker.record_field_conflicts[slot] = actual
+	checker.record_field_conflict_spans[slot] = span
+}
+
+merge_record_field_default :: proc(checker: ^Checker, slot: int, candidate: types.Type, span: source.Span) -> bool {
+	if !is_inferred_record_field(checker, slot) || !is_runtime_type(checker, candidate) {
+		return false
+	}
+	constraint := checker.record_field_constraints[slot]
+	if !types.constraint_accepts(constraint, candidate, &checker.module.types) {
+		record_field_conflict(checker, slot, candidate, span)
+		return false
+	}
+	current := checker.record_field_defaults[slot]
+	if !is_runtime_type(checker, current) {
+		checker.record_field_defaults[slot] = candidate
+		checker.record_field_demands_dirty = true
+		return true
+	}
+	if types.equal(current, candidate) {
+		return false
+	}
+	merged := types.widest(current, candidate)
+	if types.is_concrete_scalar(merged) {
+		if !types.equal(current, merged) {
+			checker.record_field_defaults[slot] = merged
+			checker.record_field_demands_dirty = true
+			return true
+		}
+		return false
+	}
+	record_field_conflict(checker, slot, candidate, span)
+	return false
+}
+
+merge_record_field_demand :: proc(checker: ^Checker, slot: int, demand: types.Type, span: source.Span) -> bool {
+	if !is_inferred_record_field(checker, slot) || !is_runtime_type(checker, demand) {
+		return false
+	}
+	constraint := checker.record_field_constraints[slot]
+	if !types.constraint_accepts(constraint, demand, &checker.module.types) {
+		record_field_conflict(checker, slot, demand, span)
+		return false
+	}
+	current := checker.module.types.fields[slot].type
+	if types.is_constraint(current) {
+		checker.module.types.fields[slot].type = demand
+		checker.record_field_demands_dirty = true
+		return true
+	}
+	if types.equal(current, demand) {
+		return false
+	}
+	merged := types.widest(current, demand)
+	if types.is_concrete_scalar(merged) {
+		if !types.equal(current, merged) {
+			checker.module.types.fields[slot].type = merged
+			checker.record_field_demands_dirty = true
+			return true
+		}
+		return false
+	}
+	record_field_conflict(checker, slot, demand, span)
+	return false
+}
+
+record_field_expr_candidate :: proc(
+	checker: ^Checker,
+	slot: int,
+	expr_id: ast.Expr_Id,
+	inferred: types.Type,
+	locals: []Infer_Local,
+	pkg: ast.Package_Id,
+	file: ast.File_Id,
+) -> bool {
+	if !is_inferred_record_field(checker, slot) || expr_id == ast.INVALID_EXPR {
+		return false
+	}
+	expr := checker.ast_module.exprs[expr_id]
+	constraint := checker.record_field_constraints[slot]
+	if constant := eval_integer_constant_in_context(checker, expr_id, pkg, file);
+	   constant.kind == .Value && fits_i64(constant.value) {
+		candidate := types.smallest_signed_for_literal(i64(constant.value))
+		if constraint == types.FLOAT {
+			candidate = types.F64
+		}
+		return merge_record_field_default(checker, slot, candidate, expr.span)
+	}
+	if is_float_constant_expr(checker, expr_id) {
+		return merge_record_field_default(checker, slot, types.F64, expr.span)
+	}
+	if numeric_operand_is_open(checker, expr_id, locals, pkg, file) {
+		candidate := inferred
+		if constraint == types.FLOAT && types.is_concrete_integer(candidate) {
+			candidate = types.F64
+		}
+		return merge_record_field_default(checker, slot, candidate, expr.span)
+	}
+	concrete := types.constraint_target(constraint, inferred, &checker.module.types)
+	if !is_runtime_type(checker, concrete) {
+		if is_runtime_type(checker, inferred) {
+			record_field_conflict(checker, slot, inferred, expr.span)
+		}
+		return false
+	}
+	return merge_record_field_demand(checker, slot, concrete, expr.span)
+}
+
+finalize_record_field_inference :: proc(checker: ^Checker) {
+	for constraint, slot in checker.record_field_constraints {
+		if !types.is_constraint(constraint) {
+			continue
+		}
+		record_name, field_name, ok := record_field_owner(checker, slot)
+		if !ok {
+			continue
+		}
+		current := checker.module.types.fields[slot].type
+		conflict := checker.record_field_conflicts[slot]
+		if types.is_valid(conflict) {
+			if is_runtime_type(checker, current) {
+				source.addf(
+					checker.diagnostics,
+					checker.record_field_conflict_spans[slot],
+					"conflicting types %s and %s for field '%s.%s' declared as '%s'",
+					types.name(current), types.name(conflict),
+					symbol_text(checker, record_name), symbol_text(checker, field_name),
+					types.name(constraint),
+				)
+			} else {
+				source.addf(
+					checker.diagnostics,
+					checker.record_field_conflict_spans[slot],
+					"type %s does not satisfy the '%s' constraint for field '%s.%s'",
+					types.name(conflict), types.name(constraint),
+					symbol_text(checker, record_name), symbol_text(checker, field_name),
+				)
+			}
+		} else if types.is_constraint(current) {
+			source.addf(
+				checker.diagnostics,
+				source.Span{},
+				"could not resolve the '%s' constraint for field '%s.%s'",
+				types.name(constraint),
+				symbol_text(checker, record_name), symbol_text(checker, field_name),
+			)
+		}
+		if types.is_constraint(current) {
+			switch constraint {
+			case types.INT:
+				checker.module.types.fields[slot].type = types.I64
+			case types.FLOAT:
+				checker.module.types.fields[slot].type = types.F64
+			case types.RANGE:
+				checker.module.types.fields[slot].type = types.range(&checker.module.types, types.I64)
+			}
+		}
+	}
+}
+
 validate_type_nodes :: proc(checker: ^Checker) {
 	for item, index in checker.module.types.nodes {
 		id := types.DYNAMIC_START+types.Type(index)
@@ -2459,9 +2672,14 @@ validate_type_nodes :: proc(checker: ^Checker) {
 			// variant has no runtime value, only a tag. Allowed only here, not for
 			// structs, untagged unions, or c_structs.
 			tagged_union := item.kind == .Union && types.is_enum(item.child, &checker.module.types)
-			for field in types.fields_for(&checker.module.types, id) {
+			for field, field_index in types.fields_for(&checker.module.types, id) {
+				field_slot := int(item.field_start)+field_index
 				if tagged_union && types.is_void(field.type) {
 					// void variant: no payload to validate.
+				} else if is_inferred_record_field(checker, field_slot) {
+					// Direct constraints in named native records are validated after the
+					// program-wide inference fixpoint. C, nested, and anonymous fields do
+					// not enter this state and retain the existing validation below.
 				} else if !types.is_runtime_value(field.type, &checker.module.types) {
 					source.add(
 						checker.diagnostics,
@@ -2850,7 +3068,11 @@ infer_compound_expr :: proc(
 		if types.is_pointer(value, store) {
 			value = types.child_type(value, store)
 		}
-		_, field, ok := find_struct_field(checker, value, expr.name)
+		slot, field, ok := find_struct_field_slot(checker, value, expr.name)
+		if ok && is_inferred_record_field(checker, slot) && is_runtime_type(checker, expected) {
+			_ = merge_record_field_demand(checker, slot, expected, expr.span)
+			field = checker.module.types.fields[slot]
+		}
 		return field.type if ok else types.INVALID
 	case .Unwrap:
 		value := infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types)
@@ -2887,15 +3109,37 @@ infer_compound_expr :: proc(
 		resize(&block_locals, capture_start)
 		return success
 	case .Struct_Literal:
-		for keyed in expr.args {
+		value := types.INVALID
-			_ = infer_nested_expr(checker, checker.ast_module.exprs[keyed].left, locals, pkg, file, demanded, local_types)
+		if expr.left != ast.INVALID_EXPR {
-		}
+			value, _ = resolve_type_argument(checker, expr.left, pkg, file)
-		if !symbol.is_valid(expr.name) {
+		} else if symbol.is_valid(expr.name) {
-			return types.INVALID
-		}
 			target_pkg, available := expr_package(checker, expr, pkg, file)
-		value := types.find_named(store, u32(target_pkg), u32(expr.name), file=u32(expr_lookup_file(expr, file))) if available else types.INVALID
+			value = types.find_named(store, u32(target_pkg), u32(expr.name), file=u32(expr_lookup_file(expr, file))) if available else types.INVALID
-		return types.resolve_alias(value, store)
+		} else {
+			value = expected
+		}
+		value = types.resolve_alias(value, store)
+		for keyed in expr.args {
+			keyed_expr := checker.ast_module.exprs[keyed]
+			if keyed_expr.left == ast.INVALID_EXPR {
+				continue
+			}
+			slot, field, ok := find_struct_field_slot(checker, value, keyed_expr.name)
+			if !ok || !is_inferred_record_field(checker, slot) {
+				_ = infer_nested_expr(checker, keyed_expr.left, locals, pkg, file, demanded, local_types)
+				continue
+			}
+			field_expected := field.type if is_runtime_type(checker, field.type) else types.INVALID
+			actual := infer_nested_expr(checker, keyed_expr.left, locals, pkg, file, demanded, local_types, field_expected)
+			_ = record_field_expr_candidate(checker, slot, keyed_expr.left, actual, locals, pkg, file)
+			if is_runtime_type(checker, checker.module.types.fields[slot].type) {
+				_ = record_demand(
+					checker, keyed_expr.left, checker.module.types.fields[slot].type,
+					locals, local_types, pkg, file,
+				)
+			}
+		}
+		return value
 	case .Keyed:
 		return infer_nested_expr(checker, expr.left, locals, pkg, file, demanded, local_types)
 	case:
@@ -2996,8 +3240,12 @@ infer_expr :: proc(
 						base_type = types.child_type(base_type, &checker.module.types)
 					}
 					if !types.is_valid(last) {
-						_, field, ok := find_struct_field(checker, base_type, expr.name)
+						slot, field, ok := find_struct_field_slot(checker, base_type, expr.name)
 						if ok {
+							if is_inferred_record_field(checker, slot) && is_runtime_type(checker, frame.expected) {
+								_ = merge_record_field_demand(checker, slot, frame.expected, expr.span)
+								field = checker.module.types.fields[slot]
+							}
 							last = field.type
 						}
 					}
@@ -3020,8 +3268,12 @@ infer_expr :: proc(
 							base_type = types.child_type(base_type, &checker.module.types)
 						}
 						if !types.is_valid(last) {
-							_, field, ok := find_struct_field(checker, base_type, expr.name)
+							slot, field, ok := find_struct_field_slot(checker, base_type, expr.name)
 							if ok {
+								if is_inferred_record_field(checker, slot) && is_runtime_type(checker, frame.expected) {
+									_ = merge_record_field_demand(checker, slot, frame.expected, expr.span)
+									field = checker.module.types.fields[slot]
+								}
 								last = field.type
 							}
 						}
@@ -3575,6 +3827,16 @@ infer_statements :: proc(
 					   locals^[local_index].mutable {
 						_ = merge_infer_local_type(checker, &locals^[local_index], value_type, local_types)
 					}
+				} else if target_expr.kind == .Field ||
+				          target_expr.kind == .Name && symbol.is_valid(target_expr.qualifier) {
+					if slot, ok := inferred_record_field_slot_from_expr(
+						checker, target_expr, locals^[:], local_types, pkg, file,
+					); ok {
+						_ = record_field_expr_candidate(
+							checker, slot, statement.expr, value_type, locals^[:], pkg, file,
+						)
+						target_type = checker.module.types.fields[slot].type
+					}
 				}
 				if !rhs_is_arith {
 					_ = record_demand(checker, statement.expr, target_type, locals^[:], local_types, pkg, file)
@@ -4097,8 +4359,39 @@ record_demand_shallow :: proc(
 	return record_demand(checker, expr_id, demand, locals, local_types, pkg, file)
 }
 
+inferred_record_field_slot_from_expr :: proc(
+	checker: ^Checker,
+	expr: ast.Expr,
+	locals: []Infer_Local,
+	local_types: []types.Type,
+	pkg: ast.Package_Id,
+	file: ast.File_Id,
+) -> (int, bool) {
+	base := types.INVALID
+	field_name := expr.name
+	if expr.kind == .Field {
+		base = infer_nested_expr(checker, expr.left, locals, pkg, file, nil, local_types)
+	} else if expr.kind == .Name && symbol.is_valid(expr.qualifier) &&
+	          find_import(checker, file, expr.qualifier) == ast.INVALID_IMPORT {
+		base = find_infer_local(locals, expr.qualifier)
+		if !types.is_valid(base) {
+			if global := find_global(checker, expr.qualifier, pkg, file); global != ast.INVALID_GLOBAL {
+				base = checker.global_types[global]
+			}
+		}
+	} else {
+		return -1, false
+	}
+	if types.is_pointer(base, &checker.module.types) {
+		base = types.child_type(base, &checker.module.types)
+	}
+	slot, _, ok := find_struct_field_slot(checker, base, field_name)
+	return slot, ok && is_inferred_record_field(checker, slot)
+}
+
 // record_demand pushes a concrete type demand onto open numeric slots reachable
-// through bare names and numeric arithmetic. Calls remain a boundary (milestone 14.5).
+// through bare names, inferred record fields, and numeric arithmetic. Calls remain
+// a boundary (milestone 14.5).
 record_demand :: proc(
 	checker: ^Checker,
 	expr_id: ast.Expr_Id,
@@ -4115,6 +4408,13 @@ record_demand :: proc(
 	expr := checker.ast_module.exprs[expr_id]
 	#partial switch expr.kind {
 	case .Name:
+		if symbol.is_valid(expr.qualifier) {
+			if slot, ok := inferred_record_field_slot_from_expr(
+				checker, expr, locals, local_types, pkg, file,
+			); ok {
+				return merge_record_field_demand(checker, slot, demand, expr.span)
+			}
+		}
 		if !symbol.is_valid(expr.qualifier) {
 			if index, ok := find_infer_local_index(locals, expr.name); ok {
 				return merge_local_demand(checker, &locals[index], demand, local_types)
@@ -4128,6 +4428,12 @@ record_demand :: proc(
 		if global != ast.INVALID_GLOBAL {
 			return merge_global_demand(checker, global, demand)
 		}
+	case .Field:
+		if slot, ok := inferred_record_field_slot_from_expr(
+			checker, expr, locals, local_types, pkg, file,
+		); ok {
+			return merge_record_field_demand(checker, slot, demand, expr.span)
+		}
 	case .Negate:
 		if types.is_signed(demand, checker.target) || types.is_float(demand, checker.target) {
 			return record_demand(checker, expr.left, demand, locals, local_types, pkg, file)
@@ -4201,6 +4507,7 @@ infer_all :: proc(checker: ^Checker) {
 	for {
 		changed := false
 		checker.global_demands_dirty = false
+		checker.record_field_demands_dirty = false
 		spec_count := len(checker.specs)
 
 		// Backward demands: a global pushes its own (declared or already-resolved) type
@@ -4286,6 +4593,9 @@ infer_all :: proc(checker: ^Checker) {
 		if checker.global_demands_dirty {
 			changed = true
 		}
+		if checker.record_field_demands_dirty {
+			changed = true
+		}
 		if !changed {
 			if !defaults_applied {
 				defaults_applied = true
@@ -4304,6 +4614,15 @@ infer_all :: proc(checker: ^Checker) {
 						defaulted = true
 					}
 				}
+				for fallback, slot in checker.record_field_defaults {
+					if !is_inferred_record_field(checker, slot) ||
+					   !types.is_constraint(checker.module.types.fields[slot].type) ||
+					   !is_runtime_type(checker, fallback) {
+						continue
+					}
+					checker.module.types.fields[slot].type = fallback
+					defaulted = true
+				}
 				if defaulted {
 					continue
 				}
@@ -4802,6 +5121,19 @@ find_struct_field :: proc(checker: ^Checker, struct_type: types.Type, name: symb
 	return 0, {}, false
 }
 
+find_struct_field_slot :: proc(checker: ^Checker, struct_type: types.Type, name: symbol.Id) -> (int, types.Field, bool) {
+	item, ok := types.node(&checker.module.types, struct_type)
+	if !ok || (item.kind != .Struct && item.kind != .Union) {
+		return -1, {}, false
+	}
+	for field, index in types.fields_for(&checker.module.types, struct_type) {
+		if field.name == u32(name) {
+			return int(item.field_start)+index, field, true
+		}
+	}
+	return -1, {}, false
+}
+
 field_type_from_value :: proc(checker: ^Checker, expr: ast.Expr, base_type: types.Type) -> types.Type {
 	store := &checker.module.types
 	field_name := symbol_text(checker, expr.name)
@@ -9956,6 +10288,11 @@ check :: proc(
 	checker.global_open_const = make([]bool, len(ast_module.globals), allocator)
 	checker.global_open_float = make([]bool, len(ast_module.globals), allocator)
 	checker.global_const_value = make([]i128, len(ast_module.globals), allocator)
+	checker.record_field_constraints = make([]types.Type, len(checker.module.types.fields), allocator)
+	checker.record_field_defaults = make([]types.Type, len(checker.module.types.fields), allocator)
+	checker.record_field_conflicts = make([]types.Type, len(checker.module.types.fields), allocator)
+	checker.record_field_conflict_spans = make([]source.Span, len(checker.module.types.fields), allocator)
+	init_record_field_inference(&checker)
 	checker.external_global_canonical = make([]ast.Global_Id, len(ast_module.globals), allocator)
 	checker.external_global_diagnostics = make([]source.Diagnostic_Id, len(ast_module.globals), allocator)
 	for &canonical in checker.external_global_canonical {
@@ -9983,6 +10320,10 @@ check :: proc(
 		delete(checker.global_open_const, allocator)
 		delete(checker.global_open_float, allocator)
 		delete(checker.global_const_value, allocator)
+		delete(checker.record_field_constraints, allocator)
+		delete(checker.record_field_defaults, allocator)
+		delete(checker.record_field_conflicts, allocator)
+		delete(checker.record_field_conflict_spans, allocator)
 		delete(checker.external_global_canonical, allocator)
 		delete(checker.external_global_diagnostics, allocator)
 		delete(checker.constants, allocator)
@@ -10043,6 +10384,7 @@ check :: proc(
 	validate_declarations(&checker)
 	configure_io_main(&checker)
 	infer_all(&checker)
+	finalize_record_field_inference(&checker)
 	validate_external_globals(&checker)
 	prune_specs(&checker)
 	build_globals(&checker)

compiler_tests.odin

@@ -7463,6 +7463,7 @@ main func() void { value Bad(i32) = undefined; _ = &value }
 		symbol.destroy_table(&symbols)
 		source.destroy_diagnostics(&diagnostics)
 	}
+
 }
 
 @(test)
@@ -7932,6 +7933,7 @@ parser_diagnoses_malformed_conditional_unwrap_captures_and_guards :: proc(t: ^te
 		symbol.destroy_table(&symbols)
 		source.destroy_diagnostics(&diagnostics)
 	}
+
 }
 
 @(test)
@@ -10998,3 +11000,218 @@ main func() void {
 	}
 	testing.expect(t, found)
 }
+
+named_record_field_type :: proc(
+	module: ^hir.Module,
+	symbols: ^symbol.Table,
+	record_name, field_name: string,
+) -> (types.Type, bool) {
+	record := types.find_named(&module.types, 0, u32(symbol.intern(symbols, record_name)))
+	if !types.is_record(record, &module.types) {
+		return types.INVALID, false
+	}
+	field_symbol := symbol.intern(symbols, field_name)
+	for field in types.fields_for(&module.types, record) {
+		if field.name == u32(field_symbol) {
+			return field.type, true
+		}
+	}
+	return types.INVALID, false
+}
+
+@(test)
+native_record_constraint_fields_resolve_program_wide :: proc(t: ^testing.T) {
+	text := `Token :: struct { start int }
+Backward :: struct { start int }
+Wide :: struct { value int }
+Literal :: struct { value int }
+Measurement :: struct {
+	ratio float
+	span range
+}
+Payload :: union { count int }
+
+take_usize func(value usize) usize { return value }
+
+exercise func(cursor usize, narrow i8, wider i16, count i32) i32 {
+	token Token = Token{start = cursor}
+	wide Wide = Wide{value = narrow}
+	wide.value = wider
+	small Literal = Literal{value = 1}
+	large Literal = Literal{value = 1000}
+	backward Backward = Backward{start = 1}
+	measurement Measurement = Measurement{ratio = 1.5, span = 0..3}
+	payload Payload = Payload{count = count}
+	_ = token.start
+	_ = wide.value
+	_ = small.value
+	_ = large.value
+	_ = take_usize(backward.start)
+	_ = measurement.ratio
+	_ = measurement.span
+	_ = payload.count
+	return 0
+}
+
+main func() i32 { return exercise(7, 1, 1000, 3) }
+`
+	source_file := source.Source{path="record_constraints.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)
+
+	token_start, token_ok := named_record_field_type(&hir_module, &symbols, "Token", "start")
+	backward_start, backward_ok := named_record_field_type(&hir_module, &symbols, "Backward", "start")
+	wide_value, wide_ok := named_record_field_type(&hir_module, &symbols, "Wide", "value")
+	literal_value, literal_ok := named_record_field_type(&hir_module, &symbols, "Literal", "value")
+	ratio, ratio_ok := named_record_field_type(&hir_module, &symbols, "Measurement", "ratio")
+	span, span_ok := named_record_field_type(&hir_module, &symbols, "Measurement", "span")
+	count, count_ok := named_record_field_type(&hir_module, &symbols, "Payload", "count")
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect(t, token_ok && backward_ok && wide_ok && literal_ok && ratio_ok && span_ok && count_ok)
+	testing.expect_value(t, token_start, types.USIZE)
+	testing.expect_value(t, backward_start, types.USIZE)
+	testing.expect_value(t, wide_value, types.I16)
+	testing.expect_value(t, literal_value, types.I16)
+	testing.expect_value(t, ratio, types.F64)
+	testing.expect(t, types.is_range(span, &hir_module.types))
+	testing.expect_value(t, types.child_type(span, &hir_module.types), types.I8)
+	testing.expect_value(t, count, types.I32)
+}
+
+@(test)
+native_record_int_field_compiles_and_runs_as_usize :: proc(t: ^testing.T) {
+	directory := "/tmp/brolang-test-record-field-usize"
+	main_path := "/tmp/brolang-test-record-field-usize/main.bro"
+	output := "/tmp/brolang-test-record-field-usize-output"
+	text := `Token :: struct { start int }
+main func() i32 {
+	cursor usize = 7
+	token Token = Token{start = cursor}
+	if (token.start != cursor) return 1
+	return 0
+}
+`
+	_ = 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)
+native_record_constraint_fields_report_unresolved_and_conflicting_demands :: proc(t: ^testing.T) {
+	cases := [2]struct {
+		text: string,
+		needle: string,
+	}{
+		{
+			text = `Token :: struct { start int }
+main func() void {}
+`,
+			needle = "could not resolve the 'int' constraint for field 'Token.start'",
+		},
+		{
+			text = `Token :: struct { start int }
+use func(signed i32, unsigned usize) void {
+	a Token = Token{start = signed}
+	b Token = Token{start = unsigned}
+	_ = a
+	_ = b
+}
+main func() void { use(1, 2) }
+`,
+			needle = "conflicting types i32 and usize for field 'Token.start' declared as 'int'",
+		},
+	}
+	for test_case in cases {
+		source_file := source.Source{path="bad_record_constraint.bro", text=test_case.text}
+		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)
+		ir_module := lower.lower(&hir_module)
+		llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+
+		matching := 0
+		for diagnostic in diagnostics.items {
+			matching += 1 if strings.contains(diagnostic.message, test_case.needle) else 0
+		}
+		testing.expect_value(t, matching, 1)
+		testing.expect(t, len(llvm_text) > 0)
+
+		delete(llvm_text)
+		ir.destroy_module(&ir_module)
+		hir.destroy_module(&hir_module)
+		ast.destroy_module(&ast_module)
+		delete(stream.items)
+		symbol.destroy_table(&symbols)
+		source.destroy_diagnostics(&diagnostics)
+	}
+
+	directory := "/tmp/brolang-test-record-field-conflict"
+	main_path := "/tmp/brolang-test-record-field-conflict/main.bro"
+	output := "/tmp/brolang-test-record-field-conflict-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)cases[1].text))
+	testing.expect_value(t, compiler_core.compile_package(directory, output), 1)
+	state := run_executable(output)
+	testing.expect(t, !state.success)
+}
+
+@(test)
+constraint_fields_remain_rejected_outside_named_native_records :: proc(t: ^testing.T) {
+	text := `BadC :: c_struct { value int }
+BadNested :: struct { values []int }
+
+make_type func() type {
+	return struct { value int }
+}
+
+main func() void {
+	Generated :: @make_type()
+	_ = Generated
+}
+`
+	source_file := source.Source{path="excluded_record_constraints.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)
+
+	record_errors := 0
+	anonymous_error := false
+	for diagnostic in diagnostics.items {
+		record_errors += 1 if strings.contains(diagnostic.message, "record fields must have runtime value types") else 0
+		anonymous_error = anonymous_error || strings.contains(diagnostic.message, "anonymous struct field 'value' requires a concrete runtime type")
+	}
+	c_field, c_ok := named_record_field_type(&hir_module, &symbols, "BadC", "value")
+	nested_field, nested_ok := named_record_field_type(&hir_module, &symbols, "BadNested", "values")
+	testing.expect_value(t, record_errors, 1)
+	testing.expect(t, anonymous_error)
+	testing.expect(t, c_ok && nested_ok)
+	testing.expect_value(t, c_field, types.INT)
+	testing.expect(t, types.is_slice(nested_field, &hir_module.types))
+	testing.expect_value(t, types.child_type(nested_field, &hir_module.types), types.INT)
+}