C++ PATCH for c++/81257, ICE with invalid ::template

C++ PATCH for c++/81257, ICE with invalid ::template

[Jason Merrill]

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The change for 54769 caused us to accept this invalid ::template A
even though the scope is non-dependent, so we can do the lookup.
Fixed by reverting part of the change to cp_parser_template_name,
which isn't actually needed.

Tested x86_64-pc-linux-gnu, applying to trunk.

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commit a553e80cfd772d103963b5176af17f9e8232c1c7
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Jun 30 16:38:14 2017 -0400

            PR c++/81257 - ICE with invalid ::template.
    
            PR c++/54769 - wrong lookup of dependent template-name.
            * parser.c (cp_parser_template_name): Revert part of last change.

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index c6a8e37..575dbfc 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -15911,11 +15911,6 @@ cp_parser_template_name (cp_parser* parser,
 				/*ambiguous_decls=*/NULL,
 				token->location);
 
-  /* If the lookup failed and we got the 'template' keyword, believe it.  */
-  if (decl == error_mark_node && template_keyword_p
-      && processing_template_decl)
-    return identifier;
-
   decl = strip_using_decl (decl);
 
   /* If DECL is a template, then the name was a template-name.  */
diff --git a/gcc/testsuite/g++.dg/parse/template-keyword1.C b/gcc/testsuite/g++.dg/parse/template-keyword1.C
new file mode 100644
index 0000000..0a1298e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/template-keyword1.C
@@ -0,0 +1,3 @@
+// PR c++/81257
+
+template < typename ::template A < int > >; // { dg-error "" }