[C++ Patch] PR 84092 ("[8 Regression] ICE on C++14 code with variable template: in build_qualified_name, at cp/tree.c:2043")

[Paolo Carlini]

Hi,

the fix for c++/81236 removed some special code for dependent_p from 
finish_id_expression, and now finish_qualified_id_expr is used for this 
snippet too. Then special code at the beginning of the latter takes care 
of calling build_qualified_name to create the relevant SCOPE_REF. 
Therefore it seems to me that - unless we really want to return an 
OFFSET_REF - at that point we are done, we don't want to get to the end 
of the following long conditional and call again build_qualified_name on 
the SCOPE_REF and ICE. We don't need convert_from_reference either 
because build_qualified_name is passed a null type. Finishing testing 
(in the library) on x86_64-linux.

Thanks! Paolo.

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

/cp
2018-01-29  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/84092
        * semantics.c (finish_qualified_id_expr): Maybe early return when 
handling
        an UNBOUND_CLASS_TEMPLATE.

/testsuite
2018-01-29  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/84092
        * g++.dg/cpp1y/var-templ57.C: New.
Index: cp/semantics.c
===================================================================
--- cp/semantics.c      (revision 257139)
+++ cp/semantics.c      (working copy)
@@ -2001,12 +2001,16 @@ finish_qualified_id_expr (tree qualifying_class,
   if (template_p)
     {
       if (TREE_CODE (expr) == UNBOUND_CLASS_TEMPLATE)
-       /* cp_parser_lookup_name thought we were looking for a type,
-          but we're actually looking for a declaration.  */
-       expr = build_qualified_name (/*type*/NULL_TREE,
-                                    TYPE_CONTEXT (expr),
-                                    TYPE_IDENTIFIER (expr),
-                                    /*template_p*/true);
+       {
+         /* cp_parser_lookup_name thought we were looking for a type,
+            but we're actually looking for a declaration.  */
+         expr = build_qualified_name (/*type*/NULL_TREE,
+                                      TYPE_CONTEXT (expr),
+                                      TYPE_IDENTIFIER (expr),
+                                      /*template_p*/true);
+         if (!(address_p && done))
+           return expr;
+       }
       else
        check_template_keyword (expr);
     }
Index: testsuite/g++.dg/cpp1y/var-templ57.C
===================================================================
--- testsuite/g++.dg/cpp1y/var-templ57.C        (nonexistent)
+++ testsuite/g++.dg/cpp1y/var-templ57.C        (working copy)
@@ -0,0 +1,4 @@
+// PR c++/84092
+// { dg-do compile { target c++14 } }
+
+template < typename T > int a (T::template b);