re PR c++/86836 (internal compiler error on structured bindings with shadow…

re PR c++/86836 (internal compiler error on structured bindings with shadow parameter on templated function)

	PR c++/86836
	* pt.c (tsubst_expr): For structured bindings, call tsubst_decomp_names
	before tsubst_init, not after it.

	* g++.dg/cpp1z/decomp46.C: New test.

From-SVN: r263391

gcc/cp/ChangeLog

 2018-08-08  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/86836
+	* pt.c (tsubst_expr): For structured bindings, call tsubst_decomp_names
+	before tsubst_init, not after it.
+
 	PR c++/86738
 	* constexpr.c (cxx_eval_binary_expression): For arithmetics involving
 	NULL pointer set *non_constant_p to true.

gcc/cp/pt.c

@@ -16740,7 +16740,17 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
 		else
 		  {
 		    int const_init = false;
+		    unsigned int cnt = 0;
+		    tree first = NULL_TREE, ndecl = error_mark_node;
 		    maybe_push_decl (decl);
+
+		    if (VAR_P (decl)
+			&& DECL_DECOMPOSITION_P (decl)
+			&& TREE_TYPE (pattern_decl) != error_mark_node)
+		      ndecl = tsubst_decomp_names (decl, pattern_decl, args,
+						   complain, in_decl, &first,
+						   &cnt);
+
 		    if (VAR_P (decl)
 			&& DECL_PRETTY_FUNCTION_P (decl))
 		      {
@@ -16756,23 +16766,14 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
 		    if (VAR_P (decl))
 		      const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
 				    (pattern_decl));
-		    if (VAR_P (decl)
-			&& DECL_DECOMPOSITION_P (decl)
-			&& TREE_TYPE (pattern_decl) != error_mark_node)
-		      {
-			unsigned int cnt;
-			tree first;
-			tree ndecl
-			  = tsubst_decomp_names (decl, pattern_decl, args,
-						 complain, in_decl, &first, &cnt);
-			if (ndecl != error_mark_node)
-			  cp_maybe_mangle_decomp (ndecl, first, cnt);
-			cp_finish_decl (decl, init, const_init, NULL_TREE, 0);
-			if (ndecl != error_mark_node)
-			  cp_finish_decomp (ndecl, first, cnt);
-		      }
-		    else
-		      cp_finish_decl (decl, init, const_init, NULL_TREE, 0);
+
+		    if (ndecl != error_mark_node)
+		      cp_maybe_mangle_decomp (ndecl, first, cnt);
+
+		    cp_finish_decl (decl, init, const_init, NULL_TREE, 0);
+
+		    if (ndecl != error_mark_node)
+		      cp_finish_decomp (ndecl, first, cnt);
 		  }
 	      }
 	  }

gcc/testsuite/ChangeLog

 2018-08-08  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/86836
+	* g++.dg/cpp1z/decomp46.C: New test.
+
 	PR c++/86738
 	* g++.dg/opt/pr86738.C: New test.
 

gcc/testsuite/g++.dg/cpp1z/decomp46.C

+// PR c++/86836
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct A {
+  int operator*();
+  void operator++();
+  bool operator!=(A);
+};
+template <typename> class map {
+public:
+  A begin();
+  A end();
+};
+
+template <typename T> void mergemap(map<T> orig, map<T> toadd) {
+  for (auto p : toadd)
+    auto [orig] = orig;		// { dg-error "use of 'orig' before deduction of 'auto'" }
+}				// { dg-warning "structured bindings only available with" "" { target c++14_down } .-1 }
+
+int
+main() {
+  map<double> x, y;
+  mergemap(x, y);
+}