-Wvariadic-macros does not print warning

Manuel López-Ibáñez lopezibanez@gmail.com
Wed Apr 23 11:34:00 GMT 2014

I think the original intention was to make it work like Wlong-long
(see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53063#c9), but it
seems it doesn't.

I think -Wpedantic should enable -Wvariadic-macros, but
-Wvariadic-macros should warn on its own without -Wpedantic. (This way
one can control -Wvariadic-macros via #pragmas and -Werror=  without
touching -Wpedantic).

Joseph, what do you think?

Prathamesh, could you open a PR in bugzilla and add manu@gcc.gnu.org
in CC and mark it as blocking PR53063 ?

I don't think I will have time to fix this in the near future, so
patches are appreciated. But it should be an easy fix, just check how
Wlong-long works in libcpp/ and c-family/ and follow the same pattern.
(The complete fix is to handle CPP options in the *.opt files, but
that could be a second step).



On 23 April 2014 12:25, Prathamesh Kulkarni <bilbotheelffriend@gmail.com> wrote:
> Hi,
> Consider the following test-case:
> #define FOO(a...)
> When compiled with: gcc -E -Wpedantic
> the following warning gets printed:
> empty-arg.c:1:14: warning: ISO C does not permit named variadic macros
> [-Wvariadic-macros]
>  #define FOO(a...)
>                      ^
> However If I only pass -Wvariadic-macros, the warning is not printed.
> For example:
> gcc -E -Wvariadic-macros
> and neither does gcc -E -Wvariadic-macros -std=c90
> Is that intended ?
> Tested on gcc-4.8.2
> gcc -v:
> Using built-in specs.
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
> Target: x86_64-linux-gnu
> Configured with: ../src/configure -v --with-pkgversion='Ubuntu
> 4.8.2-19ubuntu1'
> --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
> --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
> --program-suffix=-4.8 --enable-shared --enable-linker-build-id
> --libexecdir=/usr/lib --without-included-gettext
> --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8
> --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
> --enable-libstdcxx-debug --enable-libstdcxx-time=yes
> --enable-gnu-unique-object --disable-libmudflap --enable-plugin
> --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
> --enable-gtk-cairo
> --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre
> --enable-java-home
> --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
> --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64
> --with-arch-directory=amd64
> --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc
> --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
> --with-multilib-list=m32,m64,mx32 --with-tune=generic
> --enable-checking=release --build=x86_64-linux-gnu
> --host=x86_64-linux-gnu --target=x86_64-linux-gnu
> Thread model: posix
> gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)

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