vala: Report error for error-domains without any code

[vala-gnome.git] / vala / valamethodcall.vala

/* valamethodcall.vala
 *
 * Copyright (C) 2006-2012  Jürg Billeter
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 *
 * Author:
 *      Jürg Billeter <j@bitron.ch>
 */

using GLib;

/**
 * Represents an invocation expression in the source code.
 */
public class Vala.MethodCall : Expression {
        /**
         * The method to call.
         */
        public Expression call {
                get { return _call; }
                set {
                        _call = value;
                        _call.parent_node = this;
                }
        }

        public bool is_yield_expression { get; set; }

        public bool is_assert { get; private set; }

        /**
         * Whether this chain up uses the constructv function with va_list.
         */
        public bool is_constructv_chainup { get; private set; }

        public bool is_chainup { get; private set; }

        private Expression _call;

        private List<Expression> argument_list = new ArrayList<Expression> ();

        /**
         * Creates a new invocation expression.
         *
         * @param call             method to call
         * @param source_reference reference to source code
         * @return                 newly created invocation expression
         */
        public MethodCall (Expression call, SourceReference? source_reference = null) {
                this.source_reference = source_reference;
                this.call = call;
        }

        /**
         * Appends the specified expression to the list of arguments.
         *
         * @param arg an argument
         */
        public void add_argument (Expression arg) {
                argument_list.add (arg);
                arg.parent_node = this;
        }

        /**
         * Returns a copy of the argument list.
         *
         * @return argument list
         */
        public List<Expression> get_argument_list () {
                return argument_list;
        }

        public override void accept (CodeVisitor visitor) {
                visitor.visit_method_call (this);

                visitor.visit_expression (this);
        }

        public override void accept_children (CodeVisitor visitor) {
                call.accept (visitor);

                foreach (Expression expr in argument_list) {
                        expr.accept (visitor);
                }
        }

        public override void replace_expression (Expression old_node, Expression new_node) {
                if (call == old_node) {
                        call = new_node;
                }

                int index = argument_list.index_of (old_node);
                if (index >= 0 && new_node.parent_node == null) {
                        argument_list[index] = new_node;
                        new_node.parent_node = this;
                }
        }

        public override bool is_constant () {
                var method_type = call.value_type as MethodType;

                if (method_type != null) {
                        // N_ and NC_ do not have any effect on the C code,
                        // they are only interpreted by xgettext
                        // this means that it is ok to use them in constant initializers
                        if (method_type.method_symbol.get_full_name () == "GLib.N_") {
                                // first argument is string
                                return argument_list[0].is_constant ();
                        } else if (method_type.method_symbol.get_full_name () == "GLib.NC_") {
                                // second argument is string
                                return argument_list[1].is_constant ();
                        }
                }

                return false;
        }

        public override bool is_pure () {
                return false;
        }

        public override bool is_accessible (Symbol sym) {
                foreach (var arg in argument_list) {
                        if (!arg.is_accessible (sym)) {
                                return false;
                        }
                }

                return call.is_accessible (sym);
        }

        public override bool check (CodeContext context) {
                if (checked) {
                        return !error;
                }

                checked = true;

                if (!call.check (context)) {
                        /* if method resolving didn't succeed, skip this check */
                        error = true;
                        return false;
                }

                // type of target object
                DataType target_object_type = null;

                List<DataType> method_type_args = null;

                if (call.value_type is DelegateType) {
                        // delegate invocation, resolve generic types relative to delegate
                        target_object_type = call.value_type;
                } else if (call is MemberAccess) {
                        var ma = (MemberAccess) call;
                        if (ma.prototype_access) {
                                error = true;
                                Report.error (source_reference, "Access to instance member `%s' denied".printf (call.symbol_reference.get_full_name ()));
                                return false;
                        }

                        method_type_args = ma.get_type_arguments ();

                        if (ma.inner != null) {
                                target_object_type = ma.inner.value_type;

                                // foo is relevant instance in foo.bar.connect (on_bar)
                                if (ma.inner.symbol_reference is Signal) {
                                        var sig = ma.inner as MemberAccess;
                                        if (sig != null) {
                                                target_object_type = sig.inner.value_type;
                                        }
                                }

                                // foo is relevant instance in foo.bar.begin (bar_ready) and foo.bar.end (result)
                                var m = ma.symbol_reference as Method;
                                if (m != null && m.coroutine) {
                                        // begin or end call of async method
                                        if (ma.member_name == "begin" || ma.member_name == "end") {
                                                var method_access = ma.inner as MemberAccess;
                                                if (method_access != null && method_access.inner != null) {
                                                        target_object_type = method_access.inner.value_type;
                                                } else {
                                                        // static method
                                                        target_object_type = null;
                                                }
                                        }
                                }
                        }

                        if (ma.symbol_reference != null && ma.symbol_reference.get_attribute ("Assert") != null) {
                                this.is_assert = true;

                                var args = get_argument_list ();
                                if (args.size == 1) {
                                        this.source_reference = args[0].source_reference;
                                }
                        }
                }

                var mtype = call.value_type;
                var gobject_chainup = (context.profile == Profile.GOBJECT && call.symbol_reference == context.analyzer.object_type);
                is_chainup = gobject_chainup;

                if (!gobject_chainup) {
                        var expr = call;
                        var ma = expr as MemberAccess;
                        if (ma != null && ma.symbol_reference is CreationMethod) {
                                expr = ma.inner;
                                ma = expr as MemberAccess;
                        }
                        if (ma != null && ma.member_name == "this") {
                                // this[.with_foo] ()
                                is_chainup = true;
                        } else if (expr is BaseAccess) {
                                // base[.with_foo] ()
                                is_chainup = true;
                        }
                }

                CreationMethod base_cm = null;

                if (is_chainup) {
                        var cm = context.analyzer.find_current_method () as CreationMethod;
                        if (cm == null) {
                                error = true;
                                Report.error (source_reference, "invocation not supported in this context");
                                return false;
                        } else if (cm.chain_up) {
                                error = true;
                                Report.error (source_reference, "Multiple constructor calls in the same constructor are not permitted");
                                return false;
                        }
                        cm.chain_up = true;

                        if (mtype is ObjectType) {
                                var otype = (ObjectType) mtype;
                                var cl = (Class) otype.type_symbol;
                                base_cm = cl.default_construction_method;
                                if (base_cm == null) {
                                        error = true;
                                        Report.error (source_reference, "chain up to `%s' not supported".printf (cl.get_full_name ()));
                                        return false;
                                } else if (!base_cm.has_construct_function) {
                                        error = true;
                                        Report.error (source_reference, "chain up to `%s' not supported".printf (base_cm.get_full_name ()));
                                        return false;
                                }
                        } else if (call.symbol_reference is CreationMethod && call.symbol_reference.parent_symbol is Class) {
                                base_cm = (CreationMethod) call.symbol_reference;
                                if (!base_cm.has_construct_function) {
                                        error = true;
                                        Report.error (source_reference, "chain up to `%s' not supported".printf (base_cm.get_full_name ()));
                                        return false;
                                }
                        } else if (gobject_chainup) {
                                var cl = cm.parent_symbol as Class;
                                if (cl == null || !cl.is_subtype_of (context.analyzer.object_type)) {
                                        error = true;
                                        Report.error (source_reference, "chain up to `GLib.Object' not supported");
                                        return false;
                                }
                                call.value_type = new ObjectType (context.analyzer.object_type);
                                mtype = call.value_type;
                        }
                }

                // check for struct construction
                if (call is MemberAccess &&
                    ((call.symbol_reference is CreationMethod
                      && call.symbol_reference.parent_symbol is Struct)
                     || call.symbol_reference is Struct)) {
                        var st = call.symbol_reference as Struct;
                        if (st != null && st.default_construction_method == null && (st.is_boolean_type () || st.is_integer_type () || st.is_floating_type ())) {
                                error = true;
                                Report.error (source_reference, "invocation not supported in this context");
                                return false;
                        }

                        var struct_creation_expression = new ObjectCreationExpression ((MemberAccess) call, source_reference);
                        struct_creation_expression.struct_creation = true;
                        foreach (Expression arg in get_argument_list ()) {
                                struct_creation_expression.add_argument (arg);
                        }
                        struct_creation_expression.target_type = target_type;
                        context.analyzer.replaced_nodes.add (this);
                        parent_node.replace_expression (this, struct_creation_expression);
                        struct_creation_expression.check (context);
                        return true;
                } else if (!is_chainup && call is MemberAccess && call.symbol_reference is CreationMethod) {
                        error = true;
                        Report.error (source_reference, "use `new' operator to create new objects");
                        return false;
                }

                if (!is_chainup && mtype is ObjectType) {
                        // prevent funny stuff like (new Object ()) ()
                        error = true;
                        Report.error (source_reference, "invocation not supported in this context");
                        return false;
                } else if (mtype != null && mtype.is_invokable ()) {
                        // call ok, expression is invokable
                } else if (call.symbol_reference is Class) {
                        error = true;
                        Report.error (source_reference, "use `new' operator to create new objects");
                        return false;
                } else {
                        error = true;
                        Report.error (source_reference, "invocation not supported in this context");
                        return false;
                }

                var ret_type = mtype.get_return_type ();
                var params = mtype.get_parameters ();

                if (mtype is MethodType) {
                        var m = ((MethodType) mtype).method_symbol;
                        if (m != null && m.coroutine) {
                                var ma = (MemberAccess) call;
                                if (!is_yield_expression) {
                                        // begin or end call of async method
                                        if (ma.member_name != "end") {
                                                // begin (possibly implicit)
                                                if (ma.member_name != "begin") {
                                                        Report.deprecated (ma.source_reference, "implicit .begin is deprecated");
                                                }
                                                params = m.get_async_begin_parameters ();
                                                ret_type = new VoidType ();
                                        } else {
                                                // end
                                                params = m.get_async_end_parameters ();
                                        }
                                } else if (ma.member_name == "begin" || ma.member_name == "end") {
                                        error = true;
                                        Report.error (ma.source_reference, "use of `%s' not allowed in yield statement".printf (ma.member_name));
                                }
                        }

                        if (m != null) {
                                var ma = (MemberAccess) call;
                                int n_type_params = m.get_type_parameters ().size;
                                int n_type_args = ma.get_type_arguments ().size;
                                if (n_type_args > 0 && n_type_args < n_type_params) {
                                        error = true;
                                        Report.error (ma.source_reference, "too few type arguments");
                                        return false;
                                } else if (n_type_args > 0 && n_type_args > n_type_params) {
                                        error = true;
                                        Report.error (ma.source_reference, "too many type arguments");
                                        return false;
                                }
                        }
                }

                // FIXME partial code duplication in ObjectCreationExpression.check

                Expression last_arg = null;

                var args = get_argument_list ();
                Iterator<Expression> arg_it = args.iterator ();
                foreach (Parameter param in params) {
                        if (!param.check (context)) {
                                error = true;
                        }

                        if (param.ellipsis) {
                                break;
                        }

                        if (param.params_array) {
                                var array_type = (ArrayType) param.variable_type;
                                while (arg_it.next ()) {
                                        Expression arg = arg_it.get ();

                                        /* store expected type for callback parameters */
                                        arg.target_type = array_type.element_type;
                                        arg.target_type.value_owned = array_type.value_owned;
                                }
                                break;
                        }

                        if (arg_it.next ()) {
                                Expression arg = arg_it.get ();

                                /* store expected type for callback parameters */
                                arg.formal_target_type = param.variable_type;
                                arg.target_type = arg.formal_target_type.get_actual_type (target_object_type, method_type_args, this);

                                last_arg = arg;
                        }
                }

                // concatenate stringified arguments for methods with attribute [Print]
                if (mtype is MethodType && ((MethodType) mtype).method_symbol.get_attribute ("Print") != null) {
                        var template = new Template (source_reference);
                        foreach (Expression arg in argument_list) {
                                arg.parent_node = null;
                                template.add_expression (arg);
                        }
                        argument_list.clear ();
                        add_argument (template);
                }

                // printf arguments
                if (mtype is MethodType && ((MethodType) mtype).method_symbol.printf_format) {
                        StringLiteral format_literal = null;
                        if (last_arg is NullLiteral) {
                                // do not replace explicit null
                        } else if (last_arg != null) {
                                // use last argument as format string
                                format_literal = StringLiteral.get_format_literal (last_arg);
                                if (format_literal == null && args.size == params.size - 1) {
                                        // insert "%s" to avoid issues with embedded %
                                        format_literal = new StringLiteral ("\"%s\"");
                                        format_literal.target_type = context.analyzer.string_type.copy ();
                                        argument_list.insert (args.size - 1, format_literal);

                                        // recreate iterator and skip to right position
                                        arg_it = argument_list.iterator ();
                                        foreach (Parameter param in params) {
                                                if (param.ellipsis) {
                                                        break;
                                                }
                                                arg_it.next ();
                                        }
                                }
                        } else {
                                // use instance as format string for string.printf (...)
                                var ma = call as MemberAccess;
                                if (ma != null) {
                                        format_literal = StringLiteral.get_format_literal (ma.inner);
                                }
                        }
                        if (format_literal != null) {
                                string format = format_literal.eval ();
                                if (!context.analyzer.check_print_format (format, arg_it, source_reference)) {
                                        return false;
                                }
                        }
                }

                foreach (Expression arg in get_argument_list ()) {
                        arg.check (context);
                }

                if (ret_type is VoidType) {
                        // void return type
                        if (!(parent_node is ExpressionStatement)
                            && !(parent_node is ForStatement)
                            && !(parent_node is YieldStatement)) {
                                // A void method invocation can be in the initializer or
                                // iterator of a for statement
                                error = true;
                                Report.error (source_reference, "invocation of void method not allowed as expression");
                                return false;
                        }
                }

                formal_value_type = ret_type.copy ();
                value_type = formal_value_type.get_actual_type (target_object_type, method_type_args, this);

                bool may_throw = false;

                if (mtype is MethodType) {
                        var m = ((MethodType) mtype).method_symbol;
                        if (is_yield_expression) {
                                if (!m.coroutine) {
                                        error = true;
                                        Report.error (source_reference, "yield expression requires async method");
                                }
                                if (context.analyzer.current_method == null || !context.analyzer.current_method.coroutine) {
                                        error = true;
                                        Report.error (source_reference, "yield expression not available outside async method");
                                }
                        }
                        if (m != null && m.coroutine && !is_yield_expression && ((MemberAccess) call).member_name != "end") {
                                // .begin call of async method, no error can happen here
                        } else {
                                foreach (DataType error_type in m.get_error_types ()) {
                                        may_throw = true;

                                        // ensure we can trace back which expression may throw errors of this type
                                        var call_error_type = error_type.copy ();
                                        call_error_type.source_reference = source_reference;

                                        add_error_type (call_error_type);
                                }
                        }
                        if (m.returns_floating_reference) {
                                value_type.floating_reference = true;
                        }
                        if (m.returns_modified_pointer) {
                                ((MemberAccess) call).inner.lvalue = true;
                        }
                        // avoid passing possible null to ref_sink_function without checking
                        if (may_throw && !value_type.nullable && value_type.floating_reference && ret_type is ObjectType) {
                                value_type.nullable = true;
                        }

                        var dynamic_sig = m.parent_symbol as DynamicSignal;
                        if (dynamic_sig != null && dynamic_sig.handler != null) {
                                dynamic_sig.return_type = dynamic_sig.handler.value_type.get_return_type ().copy ();
                                bool first = true;
                                foreach (Parameter param in dynamic_sig.handler.value_type.get_parameters ()) {
                                        if (first) {
                                                // skip sender parameter
                                                first = false;
                                        } else {
                                                dynamic_sig.add_parameter (param.copy ());
                                        }
                                }
                                dynamic_sig.handler.target_type = new DelegateType (dynamic_sig.get_delegate (new ObjectType ((ObjectTypeSymbol) dynamic_sig.parent_symbol), this));
                        }

                        if (m != null && m.get_type_parameters ().size > 0) {
                                var ma = (MemberAccess) call;
                                if (ma.get_type_arguments ().size == 0) {
                                        // infer type arguments
                                        foreach (var type_param in m.get_type_parameters ()) {
                                                DataType type_arg = null;

                                                // infer type arguments from arguments
                                                arg_it = args.iterator ();
                                                foreach (Parameter param in params) {
                                                        if (param.ellipsis || param.params_array) {
                                                                break;
                                                        }

                                                        if (arg_it.next ()) {
                                                                Expression arg = arg_it.get ();

                                                                type_arg = param.variable_type.infer_type_argument (type_param, arg.value_type);
                                                                if (type_arg != null) {
                                                                        break;
                                                                }

                                                                arg.target_type = arg.formal_target_type.get_actual_type (target_object_type, method_type_args, this);
                                                        }
                                                }

                                                // infer type arguments from expected return type
                                                if (type_arg == null && target_type != null) {
                                                        type_arg = m.return_type.infer_type_argument (type_param, target_type);
                                                }

                                                if (type_arg == null) {
                                                        error = true;
                                                        Report.error (ma.source_reference, "cannot infer generic type argument for type parameter `%s'".printf (type_param.get_full_name ()));
                                                        return false;
                                                }

                                                ma.add_type_argument (type_arg);
                                        }

                                        // recalculate argument target types with new information
                                        arg_it = args.iterator ();
                                        foreach (Parameter param in params) {
                                                if (param.ellipsis || param.params_array) {
                                                        break;
                                                }

                                                if (arg_it.next ()) {
                                                        Expression arg = arg_it.get ();

                                                        arg.target_type = arg.formal_target_type.get_actual_type (target_object_type, method_type_args, this);
                                                }
                                        }

                                        // recalculate return value type with new information
                                        value_type = formal_value_type.get_actual_type (target_object_type, method_type_args, this);
                                }
                        }
                        // replace method-type if needed for proper argument-check in semantic-analyser
                        if (m != null && m.coroutine) {
                                var ma = (MemberAccess) call;
                                if (ma.member_name == "end") {
                                        mtype = new MethodType (m.get_end_method ());
                                }
                        }
                } else if (mtype is ObjectType) {
                        // constructor
                        var cl = (Class) ((ObjectType) mtype).type_symbol;
                        var m = cl.default_construction_method;
                        foreach (DataType error_type in m.get_error_types ()) {
                                may_throw = true;

                                // ensure we can trace back which expression may throw errors of this type
                                var call_error_type = error_type.copy ();
                                call_error_type.source_reference = source_reference;

                                add_error_type (call_error_type);
                        }
                } else if (mtype is DelegateType) {
                        var d = ((DelegateType) mtype).delegate_symbol;
                        foreach (DataType error_type in d.get_error_types ()) {
                                may_throw = true;

                                // ensure we can trace back which expression may throw errors of this type
                                var call_error_type = error_type.copy ();
                                call_error_type.source_reference = source_reference;

                                add_error_type (call_error_type);
                        }
                }

                if (!context.analyzer.check_arguments (this, mtype, params, get_argument_list ())) {
                        error = true;
                        return false;
                }

                /* Check for constructv chain up */
                if (base_cm != null && base_cm.is_variadic () && args.size == base_cm.get_parameters ().size) {
                        var this_last_arg = args[args.size-1];
                        if (this_last_arg.value_type is StructValueType && this_last_arg.value_type.data_type == context.analyzer.va_list_type.data_type) {
                                is_constructv_chainup = true;
                        }
                }

                if (may_throw) {
                        if (parent_node is LocalVariable || parent_node is ExpressionStatement) {
                                // simple statements, no side effects after method call
                        } else if (!(context.analyzer.current_symbol is Block)) {
                                // can't handle errors in field initializers
                                Report.error (source_reference, "Field initializers must not throw errors");
                        } else {
                                // store parent_node as we need to replace the expression in the old parent node later on
                                var old_parent_node = parent_node;

                                var local = new LocalVariable (value_type.copy (), get_temp_name (), null, source_reference);
                                var decl = new DeclarationStatement (local, source_reference);

                                insert_statement (context.analyzer.insert_block, decl);

                                var temp_access = SemanticAnalyzer.create_temp_access (local, target_type);

                                // don't set initializer earlier as this changes parent_node and parent_statement
                                local.initializer = this;
                                decl.check (context);


                                // move temp variable to insert block to ensure the
                                // variable is in the same block as the declaration
                                // otherwise there will be scoping issues in the generated code
                                var block = (Block) context.analyzer.current_symbol;
                                block.remove_local_variable (local);
                                context.analyzer.insert_block.add_local_variable (local);

                                old_parent_node.replace_expression (this, temp_access);
                                temp_access.check (context);
                        }
                }

                return !error;
        }

        public override void emit (CodeGenerator codegen) {
                var method_type = call.value_type as MethodType;

                if (method_type != null && method_type.method_symbol.parent_symbol is Signal) {
                        var signal_access = ((MemberAccess) call).inner;
                        signal_access.emit (codegen);
                } else {
                        call.emit (codegen);
                }

                foreach (Expression expr in argument_list) {
                        expr.emit (codegen);
                }

                codegen.visit_method_call (this);

                codegen.visit_expression (this);
        }

        public override void get_defined_variables (Collection<Variable> collection) {
                call.get_defined_variables (collection);

                foreach (Expression arg in argument_list) {
                        arg.get_defined_variables (collection);
                }
        }

        public override void get_used_variables (Collection<Variable> collection) {
                call.get_used_variables (collection);

                foreach (Expression arg in argument_list) {
                        arg.get_used_variables (collection);
                }
        }

        public StringLiteral? get_format_literal () {
                var mtype = this.call.value_type as MethodType;
                if (mtype != null) {
                        int format_arg = mtype.method_symbol.get_format_arg_index ();
                        if (format_arg >= 0 && format_arg < argument_list.size) {
                                return StringLiteral.get_format_literal (argument_list[format_arg]);
                        }
                }

                return null;
        }
}