Bug 114306 - wrong diagnostic with -Waddress (enabled by -Wall)
Summary: wrong diagnostic with -Waddress (enabled by -Wall)
Status: RESOLVED DUPLICATE of bug 105628
Alias: None
Product: gcc
Classification: Unclassified
Component: c (show other bugs)
Version: 12.2.0
: P3 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords: diagnostic
Depends on:
Blocks: Waddress
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Reported: 2024-03-11 12:04 UTC by J. Römmler
Modified: 2024-03-11 12:32 UTC (History)
0 users

See Also:
Host:
Target:
Build:
Known to work:
Known to fail:
Last reconfirmed:


Attachments
minified test case (415 bytes, text/x-csrc)
2024-03-11 12:04 UTC, J. Römmler
Details

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Description J. Römmler 2024-03-11 12:04:40 UTC
Created attachment 57667 [details]
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
Comment 1 Andrew Pinski 2024-03-11 12:13:58 UTC
I think the warning is correct as:
(condA>0 ? cont->value : (int*)NULL)

Here cont->value can never be null due to c rules.

The above can be simplified to just

`condA>0` then. See pr 102967 too.
Comment 2 Andrew Pinski 2024-03-11 12:32:48 UTC
Dup of at least PR 105628 .

*** This bug has been marked as a duplicate of bug 105628 ***