re PR c++/79372 (ICE on C++ code with illegal decomposition declaration on…

re PR c++/79372 (ICE on C++ code with illegal decomposition declaration on x86_64-linux-gnu: in tsubst_decomp_names, at cp/pt.c:15599)

	PR c++/79372
	* decl.c (cp_finish_decomp): On error set decl type to error_mark_node.
	* pt.c (tsubst_expr): Don't call tsubst_decomp_names on decompositions
	with error_mark_node type.

	* g++.dg/cpp1z/decomp25.C: New test.

From-SVN: r245218

gcc/cp/ChangeLog

+2017-02-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/79372
+	* decl.c (cp_finish_decomp): On error set decl type to error_mark_node.
+	* pt.c (tsubst_expr): Don't call tsubst_decomp_names on decompositions
+	with error_mark_node type.
+
 2017-02-03  Jason Merrill  <jason@redhat.com>
 
 	PR c++/78689 - ICE on constructor with label

gcc/cp/decl.c

@@ -7378,6 +7378,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
 	    }
 	  first = DECL_CHAIN (first);
 	}
+      TREE_TYPE (decl) = error_mark_node;
       if (DECL_P (decl) && DECL_NAMESPACE_SCOPE_P (decl))
 	SET_DECL_ASSEMBLER_NAME (decl, get_identifier ("<decomp>"));
       return;

gcc/cp/pt.c

@@ -15765,7 +15765,9 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
 		      const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
 				    (pattern_decl));
 		    cp_finish_decl (decl, init, const_init, NULL_TREE, 0);
-		    if (VAR_P (decl) && DECL_DECOMPOSITION_P (decl))
+		    if (VAR_P (decl)
+			&& DECL_DECOMPOSITION_P (decl)
+			&& TREE_TYPE (pattern_decl) != error_mark_node)
 		      {
 			unsigned int cnt;
 			tree first;

gcc/testsuite/ChangeLog

 2017-02-06  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/79372
+	* g++.dg/cpp1z/decomp25.C: New test.
+
 	PR tree-optimization/79284
 	* gcc.c-torture/compile/pr79284.c: New test.
 

gcc/testsuite/g++.dg/cpp1z/decomp25.C

+// PR c++/79372
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+template <typename T>
+struct S
+{
+  enum E { A };
+  void f () { auto [x] = 0; x++; }	// { dg-error "cannot decompose non-array non-class type" }
+					// { dg-warning "decomposition declaration only available with" "" { target c++14_down } .-1 }
+  void g (T t) { auto [y] = t; y++; }	// { dg-error "cannot decompose non-array non-class type" }
+};					// { dg-warning "decomposition declaration only available with" "" { target c++14_down } .-1 }
+
+int
+main ()
+{
+  S <int> s;
+  s.f ();
+  s.g (5);
+}