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Build fails with strict-aliasing violations #145

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eli-schwartz opened this issue Jul 7, 2024 · 0 comments
Open

Build fails with strict-aliasing violations #145

eli-schwartz opened this issue Jul 7, 2024 · 0 comments

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@eli-schwartz
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I tried to build with the following *FLAGS to optimize the build: -flto=4 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing

The -Werror=* flags are important to detect cases where the compiler can try to optimize based on assuming UB cannot happen, and miscompile code that has UB in it. strict-aliasing issues are always bad but LTO can make them even worse.

I got this error:

[1/7] /usr/bin/x86_64-pc-linux-gnu-gcc -DARRAY_IMPORTS -DCCSYSYEM_IMPORTS -DCHARCONVERT_IMPORTS -DDATE_IMPORTS -DEBML2_UGLY_HACKS_API -DFILE_IMPORTS -DHAS_EBML2 -DMD5_IMPORTS -DMULTITHREAD_IMPORTS -DNODE_IMPORTS -DSTR_IMPORTS -Debml2_EXPORTS -Debml2_IMPORTS -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0_build/libebml2 -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2 -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/helpers -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/.. -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0_build/corec/corec  -pipe -march=native -fstack-protector-all -O2 -fdiagnostics-color=always -frecord-gcc-switches -flto=4 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing  -Wformat -Werror=format-security -Werror=implicit-function-declaration -Werror=implicit-int -Werror=int-conversion -Werror=incompatible-pointer-types -Wno-error=format-security -fPIC -MD -MT libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o -MF libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o.d -o libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o -c /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c
FAILED: libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o 
/usr/bin/x86_64-pc-linux-gnu-gcc -DARRAY_IMPORTS -DCCSYSYEM_IMPORTS -DCHARCONVERT_IMPORTS -DDATE_IMPORTS -DEBML2_UGLY_HACKS_API -DFILE_IMPORTS -DHAS_EBML2 -DMD5_IMPORTS -DMULTITHREAD_IMPORTS -DNODE_IMPORTS -DSTR_IMPORTS -Debml2_EXPORTS -Debml2_IMPORTS -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0_build/libebml2 -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2 -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/helpers -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/.. -I/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0_build/corec/corec  -pipe -march=native -fstack-protector-all -O2 -fdiagnostics-color=always -frecord-gcc-switches -flto=4 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing  -Wformat -Werror=format-security -Werror=implicit-function-declaration -Werror=implicit-int -Werror=int-conversion -Werror=incompatible-pointer-types -Wno-error=format-security -fPIC -MD -MT libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o -MF libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o.d -o libebml2/CMakeFiles/ebml2.dir/ebmlnumber.c.o -c /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c
In file included from /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/corec.h:46,
                 from /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/node/node.h:33,
                 from /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebml2/ebml.h:32,
                 from /var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:28:
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c: In function ‘RenderDataFloat’:
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:54:33: note: in definition of macro ‘SWAP32’
   54 | #define SWAP32(a) ((((uint32_t)(a) >> 24) & 0x000000FF) | (((uint32_t)(a) >> 8)  & 0x0000FF00)|\
      |                                 ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:54:72: note: in definition of macro ‘SWAP32’
   54 | #define SWAP32(a) ((((uint32_t)(a) >> 24) & 0x000000FF) | (((uint32_t)(a) >> 8)  & 0x0000FF00)|\
      |                                                                        ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:55:32: note: in definition of macro ‘SWAP32’
   55 |                   (((uint32_t)(a) << 8)  & 0x00FF0000) | (((uint32_t)(a) << 24) & 0xFF000000))
      |                                ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:55:71: note: in definition of macro ‘SWAP32’
   55 |                   (((uint32_t)(a) << 8)  & 0x00FF0000) | (((uint32_t)(a) << 24) & 0xFF000000))
      |                                                                       ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:54:33: note: in definition of macro ‘SWAP32’
   54 | #define SWAP32(a) ((((uint32_t)(a) >> 24) & 0x000000FF) | (((uint32_t)(a) >> 8)  & 0x0000FF00)|\
      |                                 ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:54:72: note: in definition of macro ‘SWAP32’
   54 | #define SWAP32(a) ((((uint32_t)(a) >> 24) & 0x000000FF) | (((uint32_t)(a) >> 8)  & 0x0000FF00)|\
      |                                                                        ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:55:32: note: in definition of macro ‘SWAP32’
   55 |                   (((uint32_t)(a) << 8)  & 0x00FF0000) | (((uint32_t)(a) << 24) & 0xFF000000))
      |                                ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:42: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                          ^~~~~~~~~~~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:55:71: note: in definition of macro ‘SWAP32’
   55 |                   (((uint32_t)(a) << 8)  & 0x00FF0000) | (((uint32_t)(a) << 24) & 0xFF000000))
      |                                                                       ^
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:75:20: note: in expansion of macro ‘SWAP64’
   75 | #define INT64BE(a) SWAP64(a)
      |                    ^~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/corec/corec/../corec/helper.h:89:33: note: in expansion of macro ‘INT64BE’
   89 | #define LOAD64BE(ptr)           INT64BE(*(uint64_t*)(ptr))
      |                                 ^~~~~~~
/var/tmp/portage/media-video/mkclean-0.9.0/work/mkclean-0.9.0/libebml2/ebmlnumber.c:187:15: note: in expansion of macro ‘LOAD64BE’
  187 |         Buf = LOAD64BE(&data.i);
      |               ^~~~~~~~
cc1: some warnings being treated as errors
ninja: build stopped: cannot make progress due to previous errors.
 * ERROR: media-video/mkclean-0.9.0::gentoo failed (compile phase):

Originally reported downstream: https://bugs.gentoo.org/861134
Full build log: build.log

Reproduced with 0.8.10, 0.9.0, and git master.
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@eli-schwartz