[Bug c++/29028] No warning about unused names introduced with using declarations

["dodji at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29028

--- Comment #4 from Dodji Seketeli <dodji at gcc dot gnu.org> 2012-09-28 12:51:42 UTC ---
Author: dodji
Date: Fri Sep 28 12:51:30 2012
New Revision: 191829

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=191829
Log:
PR c++/29028 - Missed unused warning on using declaration

In the example of the patch, g++ fails to warn that the variable N::i
(introduced via a using declaration) is unused.

This is because as we want to emit the warning in poplevel, when we
walk the local bindings returned by getdecls, we forget that a
VAR_DECL introduced by a using declaration is represented by a
TREE_LIST which TREE_VALUE is the VAR_DECL, and we wrongly look for a
bare VAR_DECL.

Fixed thus and tested on x86_64-unknown-linux-gnu against trunk.

gcc/cp/

    * decl.c (poplevel<warn_unused*>): Do not forget that some local
    bindings are represented by a TREE_LIST.

gcc/testsuite/

    * g++.dg/warn/Wunused-var-18.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/warn/Wunused-var-18.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/testsuite/ChangeLog