finite-domain enum return analysis

compiler_tests.odin

@@ -9519,6 +9519,42 @@ main func() void {
 	testing.expect(t, !found)
 }
 
+@(test)
+exhaustive_enum_guard_sequences_return :: proc(t: ^testing.T) {
+	text := `E :: enum { a, b }
+complete func(value E) i32 {
+	if (value == .a) { return 1 }
+	if (value == .b) { return 2 }
+}
+incomplete func(value E) i32 {
+	if (value == .a) { return 1 }
+}
+main func() void {
+	_ = complete(.a)
+	_ = incomplete(.a)
+}
+`
+	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)
+
+	missing_returns := 0
+	for diagnostic in diagnostics.items {
+		if strings.contains(diagnostic.message, "does not return a value") {
+			missing_returns += 1
+		}
+	}
+	testing.expect_value(t, missing_returns, 1)
+}
+
 @(test)
 conditional_unwrap_compiles_and_runs :: proc(t: ^testing.T) {
 	output := "/tmp/brolang-test-conditional-unwrap"
@@ -13844,6 +13880,18 @@ init func($E, $V type, values meta.EnumFieldStruct(E, ?V, some!(none))) Map(E, V
 	return map
 }
 
+get func($E, $V type, map @Map(E, V), key E) ?V {
+	match typeinfo!(E) {
+		.enum |info|: expand for info.fields |field, index| {
+			if key == field!(E, field.name) {
+				if map.present[index] { return map.values[index] }
+				return none
+			}
+		}
+		else: compile_error!("EnumMap key must be an enum")
+	}
+}
+
 main func() i32 {
 	_ = ordered
 	inferred :: {x = 40, name = "bro"}
@@ -13889,6 +13937,10 @@ 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| {
+		if value.len != 10 { return 19 }
+	} else { return 20 }
+	if get(TokenKind, []u8, &map, TokenKind.eof) |_| { return 21 }
 	return 0
 }
 `