structs as errors in fallibles

compiler_tests.odin

@@ -6953,6 +6953,51 @@ 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 }