Remove try; Replace try x else y with or_else(x, y)

src/check_builtin.cpp

@@ -47,6 +47,72 @@ BuiltinTypeIsProc *builtin_type_is_procs[BuiltinProc__type_simple_boolean_end -
 	type_has_nil,
 };
 
+
+void check_try_split_types(CheckerContext *c, Operand *x, String const &name, Type **left_type_, Type **right_type_) {
+	Type *left_type = nullptr;
+	Type *right_type = nullptr;
+	if (x->type->kind == Type_Tuple) {
+		auto const &vars = x->type->Tuple.variables;
+		auto lhs = array_slice(vars, 0, vars.count-1);
+		auto rhs = vars[vars.count-1];
+		if (lhs.count == 1) {
+			left_type = lhs[0]->type;
+		} else if (lhs.count != 0) {
+			left_type = alloc_type_tuple();
+			left_type->Tuple.variables = array_make_from_ptr(lhs.data, lhs.count, lhs.count);
+		}
+
+		right_type = rhs->type;
+	} else {
+		check_promote_optional_ok(c, x, &left_type, &right_type);
+	}
+
+	if (left_type_)  *left_type_  = left_type;
+	if (right_type_) *right_type_ = right_type;
+
+	if (!is_type_boolean(right_type)) {
+		gbString str = type_to_string(right_type);
+		error(x->expr, "'%.*s' expects an \"optional ok\" like value, got %s", LIT(name), str);
+		gb_string_free(str);
+	}
+	// if (!type_has_nil(right_type) && !is_type_boolean(right_type)) {
+	// 	gbString str = type_to_string(right_type);
+	// 	error(x->expr, "'%.*s' expects an \"optional ok\" like value, or an n-valued expression where the last value is either a boolean or can be compared against 'nil', got %s", LIT(name), str);
+	// 	gb_string_free(str);
+	// }
+}
+
+
+void check_try_expr_no_value_error(CheckerContext *c, String const &name, Operand const &x, Type *type_hint) {
+	// TODO(bill): better error message
+	gbString t = type_to_string(x.type);
+	error(x.expr, "'%.*s' does not return a value, value is of type %s", LIT(name), t);
+	if (is_type_union(type_deref(x.type))) {
+		Type *bsrc = base_type(type_deref(x.type));
+		gbString th = nullptr;
+		if (type_hint != nullptr) {
+			GB_ASSERT(bsrc->kind == Type_Union);
+			for_array(i, bsrc->Union.variants) {
+				Type *vt = bsrc->Union.variants[i];
+				if (are_types_identical(vt, type_hint)) {
+					th = type_to_string(type_hint);
+					break;
+				}
+			}
+		}
+		gbString expr_str = expr_to_string(x.expr);
+		if (th != nullptr) {
+			error_line("\tSuggestion: was a type assertion such as %s.(%s) or %s.? wanted?\n", expr_str, th, expr_str);
+		} else {
+			error_line("\tSuggestion: was a type assertion such as %s.(T) or %s.? wanted?\n", expr_str, expr_str);
+		}
+		gb_string_free(th);
+		gb_string_free(expr_str);
+	}
+	gb_string_free(t);
+}
+
+
 bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32 id, Type *type_hint) {
 	ast_node(ce, CallExpr, call);
 	if (ce->inlining != ProcInlining_none) {
@@ -84,6 +150,9 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		// NOTE(bill): The first arg may be a Type, this will be checked case by case
 		break;
 
+	case BuiltinProc_or_else:
+		// NOTE(bill): The arguments may be multi-expr
+		break;
 
 	case BuiltinProc_DIRECTIVE: {
 		ast_node(bd, BasicDirective, ce->proc);
@@ -1712,6 +1781,47 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		break;
 	}
 
+	case BuiltinProc_or_else: {
+		GB_ASSERT(ce->args.count == 2);
+		Ast *arg = ce->args[0];
+		Ast *default_value = ce->args[1];
+
+		Operand x = {};
+		Operand y = {};
+		check_multi_expr_with_type_hint(c, &x, arg, type_hint);
+		if (x.mode == Addressing_Invalid) {
+			operand->mode = Addressing_Value;
+			operand->type = t_invalid;
+			return false;
+		}
+
+		check_multi_expr_with_type_hint(c, &y, default_value, x.type);
+		error_operand_no_value(&y);
+		if (y.mode == Addressing_Invalid) {
+			operand->mode = Addressing_Value;
+			operand->type = t_invalid;
+			return false;
+		}
+
+		Type *left_type = nullptr;
+		Type *right_type = nullptr;
+		check_try_split_types(c, &x, builtin_name, &left_type, &right_type);
+		add_type_and_value(&c->checker->info, arg, x.mode, x.type, x.value);
+
+		if (left_type != nullptr) {
+			check_assignment(c, &y, left_type, builtin_name);
+		} else {
+			check_try_expr_no_value_error(c, builtin_name, x, type_hint);
+		}
+
+		if (left_type == nullptr) {
+			left_type = t_invalid;
+		}
+		operand->mode = Addressing_Value;
+		operand->type = left_type;
+		return true;
+	}
+
 	case BuiltinProc_simd_vector: {
 		Operand x = {};
 		Operand y = {};