re PR c++/83796 (Abstract classes allowed to be instantiated when initialised as…

re PR c++/83796 (Abstract classes allowed to be instantiated when initialised as default parameter to function or constructor)

/cp
2018-02-01  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/83796
	* call.c (convert_like_real): If w're initializing from {} explicitly
	call abstract_virtuals_error_sfinae.

/testsuite
2018-02-01  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/83796
	* g++.dg/cpp0x/abstract-default1.C: New.

From-SVN: r257298

gcc/cp/ChangeLog

+2018-02-01  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/83796
+	* call.c (convert_like_real): If w're initializing from {} explicitly
+	call abstract_virtuals_error_sfinae.
+
 2018-01-31  Jason Merrill  <jason@redhat.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 

gcc/cp/call.c

@@ -6765,6 +6765,8 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 	    && TYPE_HAS_DEFAULT_CONSTRUCTOR (totype))
 	  {
 	    bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr);
+	    if (abstract_virtuals_error_sfinae (NULL_TREE, totype, complain))
+	      return error_mark_node;
 	    expr = build_value_init (totype, complain);
 	    expr = get_target_expr_sfinae (expr, complain);
 	    if (expr != error_mark_node)

gcc/testsuite/ChangeLog

+2018-02-01  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/83796
+	* g++.dg/cpp0x/abstract-default1.C: New.
+
 2018-02-01  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	PR tree-optimization/81635

gcc/testsuite/g++.dg/cpp0x/abstract-default1.C

+// PR c++/83796
+// { dg-do compile { target c++11 } }
+
+struct MyAbstractClass
+{
+  virtual int foo() const = 0;
+};
+
+struct TestClass
+{
+  TestClass(const MyAbstractClass& m = {})  // { dg-error "abstract type" }
+  : value_(m.foo()) {}
+
+  int value_;
+};
+
+int TestFunction(const MyAbstractClass& m = {})  // { dg-error "abstract type" }
+{
+  return m.foo();
+}
+
+int main()
+{
+  TestClass testInstance;  // { dg-error "abstract type" }
+  TestFunction();  // { dg-error "abstract type" }
+}