[C++ Patch] PR 62315 ("do not print typename in diagnostic if the original code does not have it")

[Paolo Carlini]

Hi,

a while ago Manuel noticed that printing 'typename' in error messages 
about missing 'typename' can be confusing. That seems easy to fix, in 
fact we already handle correctly a similar situation in grokdeclarator. 
Tested x86_64-linux.

Thanks, Paolo.

//////////////////


/cp
2017-06-02  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/62315
        * parser.c (cp_parser_diagnose_invalid_type_name): Don't print
        'typename' in error messages about missing 'typename'.

/testsuite
2017-06-02  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/62315
        * g++.dg/parse/typedef2.C: Specify a dg-error string.
Index: testsuite/g++.dg/parse/typedef2.C
===================================================================
--- testsuite/g++.dg/parse/typedef2.C   (revision 248783)
+++ testsuite/g++.dg/parse/typedef2.C   (working copy)
@@ -1,3 +1,2 @@
 template <typename T> struct B { typedef typename T::X X; };
-template <typename T> struct A { typedef B<T>::X::Y Z; }; // { dg-error "" }
- 
+template <typename T> struct A { typedef B<T>::X::Y Z; }; // { dg-error 
"before 'B<T>::X::Y' because 'B<T>::X'" }
Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 248783)
+++ cp/parser.c (working copy)
@@ -3270,9 +3270,21 @@ cp_parser_diagnose_invalid_type_name (cp_parser *p
        }
       else if (TYPE_P (parser->scope)
               && dependent_scope_p (parser->scope))
-       error_at (location, "need %<typename%> before %<%T::%E%> because "
-                 "%qT is a dependent scope",
-                 parser->scope, id, parser->scope);
+       {
+         if (TREE_CODE (parser->scope) == TYPENAME_TYPE)
+           error_at (location,
+                     "need %<typename%> before %<%T::%D::%E%> because "
+                     "%<%T::%D%> is a dependent scope",
+                     TYPE_CONTEXT (parser->scope),
+                     TYPENAME_TYPE_FULLNAME (parser->scope),
+                     id,
+                     TYPE_CONTEXT (parser->scope),
+                     TYPENAME_TYPE_FULLNAME (parser->scope));
+         else
+           error_at (location, "need %<typename%> before %<%T::%E%> because "
+                     "%qT is a dependent scope",
+                     parser->scope, id, parser->scope);
+       }
       else if (TYPE_P (parser->scope))
        {
          if (!COMPLETE_TYPE_P (parser->scope))