re PR c++/78896 ([C++17] Segmentation fault occurs when use variable initialized…

re PR c++/78896 ([C++17] Segmentation fault occurs when use variable initialized using structured binding with capture-by-ref lambda)

	PR c++/78896
	* decl.c (cp_finish_decomp): Disallow memberwise decomposition of
	lambda expressions.

	* g++.dg/cpp1z/decomp24.C: New test.

From-SVN: r244909

gcc/cp/ChangeLog

 2017-01-25  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/78896
+	* decl.c (cp_finish_decomp): Disallow memberwise decomposition of
+	lambda expressions.
+
 	PR c++/77914
 	* parser.c (cp_parser_lambda_declarator_opt): Pedwarn with
 	OPT_Wpedantic on lambda templates for -std=c++14 and higher.

gcc/cp/decl.c

@@ -7562,6 +7562,11 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
       error_at (loc, "cannot decompose non-array non-class type %qT", type);
       goto error_out;
     }
+  else if (LAMBDA_TYPE_P (type))
+    {
+      error_at (loc, "cannot decompose lambda closure type %qT", type);
+      goto error_out;
+    }
   else
     {
       tree btype = find_decomp_class_base (loc, type, NULL_TREE);

gcc/testsuite/ChangeLog

 2017-01-25  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/78896
+	* g++.dg/cpp1z/decomp24.C: New test.
+
 	PR c++/77914
 	* g++.dg/cpp1y/lambda-generic-77914.C: New test.
 	* g++.dg/cpp1y/lambda-generic-dep.C: Add -pedantic to dg-options,

gcc/testsuite/g++.dg/cpp1z/decomp24.C

+// PR c++/78896
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+int
+foo ()
+{
+  int a {10};
+  auto [b] { [&a](){} };	// { dg-error "cannot decompose lambda closure type" }
+  return b - a;			// { dg-warning "decomposition declaration only available with" "" { target c++14_down } .-1 }
+}