.. Ah! I think I have a much better tentative fix, which, as it happens,
also leads to a diagnostics quite close to that produced by the EDG
front-end.
The idea is checking for the offending case and not handling it in any
special way besides turning need_new = 1, as if for a normal new
declaration: actually in this case it conflicts with the existing one
from the namespace alias declaration, and leads to a guaranteed error a
bit later. Patch passes testing.
Thanks,
Paolo.
///////////////////////
Index: testsuite/g++.dg/parse/namespace-alias-1.C
===================================================================
--- testsuite/g++.dg/parse/namespace-alias-1.C (revision 0)
+++ testsuite/g++.dg/parse/namespace-alias-1.C (revision 0)
@@ -0,0 +1,7 @@
+// PR c++/26155
+
+namespace N
+{
+ namespace M = N; // { dg-error "previous declaration" }
+ namespace M {} // { dg-error "declaration of namespace" }
+}
Index: cp/name-lookup.c
===================================================================
--- cp/name-lookup.c (revision 187991)
+++ cp/name-lookup.c (working copy)
@@ -3544,12 +3544,20 @@ push_namespace (tree name)
d = IDENTIFIER_NAMESPACE_VALUE (name);
if (d != NULL_TREE && TREE_CODE (d) == NAMESPACE_DECL)
{
+ tree dna = DECL_NAMESPACE_ALIAS (d);
need_new = 0;
- if (DECL_NAMESPACE_ALIAS (d))
+ if (dna)
{
- error ("namespace alias %qD not allowed here, assuming %qD",
- d, DECL_NAMESPACE_ALIAS (d));
- d = DECL_NAMESPACE_ALIAS (d);
+ if (NAMESPACE_LEVEL (dna)->level_chain
+ == current_binding_level)
+ {
+ error ("namespace alias %qD not allowed here, "
+ "assuming %qD", d, dna);
+ d = dna;
+ }
+ else
+ /* We error out below. */
+ need_new = 1;
}
}
}
