[Bug c++/59574] New: Bad -Wattributes: ignoring attributes applied after definition

[jed at 59A2 dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59574

            Bug ID: 59574
           Summary: Bad -Wattributes: ignoring attributes applied after
                    definition
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jed at 59A2 dot org

Created attachment 31499
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31499&action=edit
Test case.  Works with gcc if renamed to "unused.c"

g++ misinterprets the attribute tag in

Type x,__attribute((unused)) y;

when Type is a struct or union.  gcc interprets this correctly (rename to
"unused.c", as does clang++.

unused.cc: In function ‘MyInt bad_Wattributes()’:
unused.cc:11:40: warning: ignoring attributes applied to ‘MyInt’ after
definition [-Wattributes]
   struct MyInt x,__attribute((unused)) y;
                                        ^

Verbose output below:

$ g++ -v -save-temps -c -Wall -Wextra unused.cc                   
Using built-in specs.
COLLECT_GCC=g++
Target: x86_64-unknown-linux-gnu
Configured with: /build/gcc-multilib/src/gcc-4.8.2/configure --prefix=/usr
--libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared
--enable-threads=posix --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-cloog-backend=isl --disable-cloog-version-check --enable-lto
--enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu
--enable-multilib --disable-werror --enable-checking=release
Thread model: posix
gcc version 4.8.2 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-Wall' '-Wextra' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/cc1plus -E -quiet -v -D_GNU_SOURCE
unused.cc -mtune=generic -march=x86-64 -Wall -Wextra -fpch-preprocess -o
unused.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../include/c++/4.8.2

/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../include/c++/4.8.2/x86_64-unknown-linux-gnu

/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../include/c++/4.8.2/backward
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/include
 /usr/local/include
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-Wall' '-Wextra' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/cc1plus -fpreprocessed unused.ii
-quiet -dumpbase unused.cc -mtune=generic -march=x86-64 -auxbase unused -Wall
-Wextra -version -o unused.s
GNU C++ (GCC) version 4.8.2 (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version
3.1.2-p5, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.8.2 (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version
3.1.2-p5, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: ab71b98845e83cf5a6c15196f260f6ae
unused.cc: In function ‘MyInt bad_Wattributes()’:
unused.cc:11:40: warning: ignoring attributes applied to ‘MyInt’ after
definition [-Wattributes]
   struct MyInt x,__attribute((unused)) y;
                                        ^
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-Wall' '-Wextra' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 as -v --64 -o unused.o unused.s
GNU assembler version 2.24 (x86_64-unknown-linux-gnu) using BFD version (GNU
Binutils) 2.24
COMPILER_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-Wall' '-Wextra' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'