https://bugs.kde.org/show_bug.cgi?id=486093
Bug ID: 486093
Summary: -Wstrict-aliasing in tests
Classification: Developer tools
Product: valgrind
Version: 3.22 GIT
Platform: Other
OS: Other
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: s...@gentoo.org
Target Milestone: ---
THere's a lot of -Wstrict-aliasing instances in the testsuite. In Gentoo, we
try to recommend people to use -Werror=strict-aliasing
-Werror=lto-type-mismatch -Werror=some-other-bits when using LTO to help find
likely runtime problems (Valgrind isn't LTO-compaitble for other reasons but
that's neither here nor there for this).
When building Valgrind with such, we get:
```
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I../../.. -I../../..
-I../../../include -I../../../coregrind -I../../../include -I../../../VEX/pub
-I../../../VEX/pub -DVGA_amd64=1 -DVGO_l
inux=1 -DVGP_amd64_linux=1 -DVGPV_amd64_linux_vanilla=1 -DVGA_SEC_x86=1
-DVGP_SEC_amd64_linux=1 -Winline -Wall -Wshadow -Wno-long-long -g
-fno-stack-protector -m64 -O -ffast-math -
mfpmath=387 -mfancy-math-387 -O3 -march=native -mtls-dialect=gnu2
-fno-semantic-interposition -pipe -fcf-protection=none
-fdiagnostics-color=always -fdiagnostics-urls=never -frecord-gcc
-switches -Wa,-O2 -Wa,-mtune=znver2 -Wstrict-aliasing -Wfree-nonheap-object
-Werror=lto-type-mismatch -Werror=strict-aliasing -Werror=odr -Wstrict-aliasing
-Wfree-nonheap-object -Werror
=lto-type-mismatch -Werror=strict-aliasing -Werror=odr
-Wbuiltin-declaration-mismatch -ggdb3 -Wformat -Wformat-security -Waddress
-Warray-bounds -Wfree-nonheap-object -Wint-to-pointer-c
ast -Wmain -Wnonnull -Wodr -Wreturn-type -Wsizeof-pointer-memaccess
-Wstrict-aliasing -Wstring-compare -Wuninitialized -Wvarargs
-fno-stack-protector -fno-harden-control-flow-redundancy
-c -o more_x87_fp-more_x87_fp.o `test -f 'more_x87_fp.c' || echo
'./'`more_x87_fp.c
make[5]: 'shr_edx' is up to date.
more_x87_fp.c: In function ‘test_fcvt’:
more_x87_fp.c:108:28: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
108 | printf("a=%016llx\n", *(long long *)&a);
| ^~~~~~~~~~~~~~~
more_x87_fp.c:109:34: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
109 | printf("la=%016llx %04x\n", *(long long *)&la,
| ^~~~~~~~~~~~~~~~
more_x87_fp.c:110:12: warning: ‘la’ is used uninitialized [-Wuninitialized]
110 | *(unsigned short *)((char *)(&la) + 8));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
more_x87_fp.c:96:17: note: ‘la’ declared here
96 | long double la;
| ^~
cc1: some warnings being treated as errors
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I../../.. -I../../..
-I../../../include -I../../../coregrind -I../../../include -I../../../VEX/pub
-I../../../VEX/pub -DVGA_amd64=1 -DVGO_l
inux=1 -DVGP_amd64_linux=1 -DVGPV_amd64_linux_vanilla=1 -DVGA_SEC_x86=1
-DVGP_SEC_amd64_linux=1 -Winline -Wall -Wshadow -Wno-long-long -g
-fno-stack-protector -m32 -mmmx -msse -O3 -
march=native -mtls-dialect=gnu2 -fno-semantic-interposition -pipe
-fcf-protection=none -fdiagnostics-color=always -fdiagnostics-urls=never
-frecord-gcc-switches -Wa,-O2 -Wa,-mtune=znver
2 -Wstrict-aliasing -Wfree-nonheap-object -Werror=lto-type-mismatch
-Werror=strict-aliasing -Werror=odr -Wstrict-aliasing -Wfree-nonheap-object
-Werror=lto-type-mismatch -Werror=strict-
aliasing -Werror=odr -Wbuiltin-declaration-mismatch -ggdb3 -Wformat
-Wformat-security -Waddress -Warray-bounds -Wfree-nonheap-object
-Wint-to-pointer-cast -Wmain -Wnonnull -Wodr -Wretur
n-type -Wsizeof-pointer-memaccess -Wstrict-aliasing -Wstring-compare
-Wuninitialized -Wvarargs -fno-stack-protector
-fno-harden-control-flow-redundancy -c -o more_x86_fp.o more_x86_fp.c
more_x86_fp.c: In function ‘test_fcvt’:
more_x86_fp.c:98:28: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
98 | printf("a=%016llx\n", *(long long *)&a);
| ^~~~~~~~~~~~~~~
more_x86_fp.c:99:34: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
99 | printf("la=%016llx %04x\n", *(long long *)&la,
| ^~~~~~~~~~~~~~~~
more_x86_fp.c:100:12: warning: ‘la’ is used uninitialized [-Wuninitialized]
100 | *(unsigned short *)((char *)(&la) + 8));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
more_x86_fp.c:86:17: note: ‘la’ declared here
86 | long double la;
| ^~
cc1: some warnings being treated as errors
```
This is with `gcc version 14.0.1 20240423 (experimental)
0c8e99e5c32be9f2604f3c330814993f29818037 (Gentoo Hardened 14.0.9999 p, commit
257336021ebdc63cdd390487506f23d83f04ab91)` but I've been seeing this for a
while and just slacked on reporting it.
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