[Bug c/114306] New: wrong diagnostic with -Waddress (enabled by -Wall)

["jochen447 at concept dot de" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114306

            Bug ID: 114306
           Summary: wrong diagnostic with -Waddress (enabled by -Wall)
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jochen447 at concept dot de
  Target Milestone: ---

Created attachment 57667
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57667&action=edit
minified test case

The compiler option -Waddress erroneously reports a warning for the attached
simplified test case (warn_gcc.c):

$ gcc -Waddress warn_gcc.c -o warn_gcc
warn_gcc.c: In function ‘func’:
warn_gcc.c:17:49: warning: the comparison will always evaluate as ‘true’ for
the address of ‘value’ will never be NULL [-Waddress]
   17 |     return (condA>0 ? cont->value : (int*)NULL) ? "foo" : "bar";
      |                                                 ^
warn_gcc.c:13:9: note: ‘value’ declared here
   13 |     int value[1];
      |         ^~~~~

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/12/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 12.2.0-14'
--with-bugurl=file:///usr/share/doc/gcc-12/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-12
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new
--enable-gnu-unique-object --disable-vtable-verify --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-12-bTRWOB/gcc-12-12.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-12-bTRWOB/gcc-12-12.2.0/debian/tmp-gcn/usr
--enable-offload-defaulted --without-cuda-driver --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.0 (Debian 12.2.0-14)

$ uname -a
Linux linux64c 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1
(2024-02-01) x86_64 GNU/Linux

$ cat /etc/debian_version
12.5