Tests fail with LTO due to ODR / type mismatch violations

[eli-schwartz]

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

Link-Time Optimization is a massively global compiler optimization pass which is pretty handy for producing faster executables. It also has the interesting property that because the compiler does whole-program analysis using bytecode, it can save type information and perform error checks that it normally doesn’t have enough insight for. In particular, checking for ODR issues and checking function type signature mismatches.

Note that all the -Werror=* flags are used to help detect cases where the compiler tries to optimize by assuming UB cannot exist in the source code -- if it does exist, ordinarily the code would be miscompiled, and this says to make the miscompilation a fatal error.

I got this error:

gcc.link ../../../bin.v2/libs/smart_ptr/test/abi_test_mt_nt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_mt_nt

    "x86_64-pc-linux-gnu-g++"  -Wl,-rpath -Wl,"/var/tmp/portage/dev-libs/boost-1.89.0/work/boost_1_89_0-abi_x86_64.amd64/bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden" -Wl,-rpath-link -Wl,"/var/tmp/portage/dev-libs/boost-1.89.0/work/boost_1_89_0-abi_x86_64.amd64/bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden" -o "../../../bin.v2/libs/smart_ptr/test/abi_test_mt_nt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_mt_nt" -Wl,--start-group "../../../bin.v2/libs/smart_ptr/test/abi_test_mt_nt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_main.o" "../../../bin.v2/libs/smart_ptr/test/gcc-14.3/gentoorelease/x86_64/link-static/pch-off/threading-multi/visibility-hidden/libabi_test_nt.a" "../../../bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/libboost_atomic.so.1.89.0" "../../../bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/link-static/pch-off/threading-multi/visibility-hidden/libboost_atomic.a"  -Wl,-Bstatic  -Wl,-Bdynamic -lrt -Wl,--end-group -fPIC -m64 -pthread -fvisibility=hidden -fvisibility-inlines-hidden -Wl,-O1 -Wl,--as-needed -Wl,-z,pack-relative-relocs -flto=4 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -Wl,--defsym=__gentoo_check_ldflags__=0 

../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:70:28: error: type ‘struct sp_counted_base’ violates the C++ One Definition Rule [-Werror=odr]
   70 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:38:28: note: a different type is defined in another translation unit
   38 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:77:27: note: the first difference of corresponding definitions is field ‘use_count_’
   77 |     boost::uint_least32_t use_count_;        // #shared
      |                           ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:45:26: note: a field of same name but different type is defined in another translation unit
   45 |     boost::int_least32_t use_count_;        // #shared
      |                          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:70:28: note: type ‘uint_least32_t’ should match type ‘int_least32_t’
   70 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:86:10: error: type of ‘release’ does not match original declaration [-Werror=lto-type-mismatch]
   86 |     void release() noexcept
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:116:10: note: ‘release’ was previously declared here
  116 |     void release() // nothrow
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:116:10: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:100:10: error: type of ‘weak_release’ does not match original declaration [-Werror=lto-type-mismatch]
  100 |     void weak_release() noexcept
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:130:10: note: ‘weak_release’ was previously declared here
  130 |     void weak_release() // nothrow
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:130:10: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:65:18: error: type of ‘destroy’ does not match original declaration [-Werror=lto-type-mismatch]
   65 |     virtual void destroy() noexcept // nothrow
      |                  ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:97:18: note: ‘destroy’ was previously declared here
   97 |     virtual void destroy() // nothrow
      |                  ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:97:18: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
lto1: some warnings being treated as errors
lto-wrapper: fatal error: /usr/bin/x86_64-pc-linux-gnu-g++ returned 1 exit status
compilation terminated.
/usr/lib/gcc/x86_64-pc-linux-gnu/14/../../../../x86_64-pc-linux-gnu/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status
...skipped <p../../../bin.v2/libs/smart_ptr/test/abi_test_mt_nt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden>abi_test_mt_nt.run for lack of <p../../../bin.v2/libs/smart_ptr/test/abi_test_mt_nt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden>abi_test_mt_nt...
common.mkdir ../../../bin.v2/libs/smart_ptr/test/get_deleter_test2_no_rtti.test

        mkdir -p "../../../bin.v2/libs/smart_ptr/test/get_deleter_test2_no_rtti.test"
    
gcc.link ../../../bin.v2/libs/smart_ptr/test/abi_test_nt_mt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_nt_mt

    "x86_64-pc-linux-gnu-g++"  -Wl,-rpath -Wl,"/var/tmp/portage/dev-libs/boost-1.89.0/work/boost_1_89_0-abi_x86_64.amd64/bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden" -Wl,-rpath-link -Wl,"/var/tmp/portage/dev-libs/boost-1.89.0/work/boost_1_89_0-abi_x86_64.amd64/bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden" -o "../../../bin.v2/libs/smart_ptr/test/abi_test_nt_mt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_nt_mt" -Wl,--start-group "../../../bin.v2/libs/smart_ptr/test/abi_test_nt_mt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/abi_test_main.o" "../../../bin.v2/libs/smart_ptr/test/gcc-14.3/gentoorelease/x86_64/link-static/pch-off/threading-multi/visibility-hidden/libabi_test_mt.a" "../../../bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden/libboost_atomic.so.1.89.0" "../../../bin.v2/libs/atomic/build/gcc-14.3/gentoorelease/x86_64/link-static/pch-off/threading-multi/visibility-hidden/libboost_atomic.a"  -Wl,-Bstatic  -Wl,-Bdynamic -lrt -Wl,--end-group -fPIC -m64 -pthread -fvisibility=hidden -fvisibility-inlines-hidden -Wl,-O1 -Wl,--as-needed -Wl,-z,pack-relative-relocs -flto=4 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -Wl,--defsym=__gentoo_check_ldflags__=0 

../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:38:28: error: type ‘struct sp_counted_base’ violates the C++ One Definition Rule [-Werror=odr]
   38 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:70:28: note: a different type is defined in another translation unit
   70 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:45:26: note: the first difference of corresponding definitions is field ‘use_count_’
   45 |     boost::int_least32_t use_count_;        // #shared
      |                          ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:77:27: note: a field of same name but different type is defined in another translation unit
   77 |     boost::uint_least32_t use_count_;        // #shared
      |                           ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:38:28: note: type ‘int_least32_t’ should match type ‘uint_least32_t’
   38 | class BOOST_SYMBOL_VISIBLE sp_counted_base
      |                            ^
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:116:10: error: type of ‘release’ does not match original declaration [-Werror=lto-type-mismatch]
  116 |     void release() // nothrow
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:86:10: note: ‘release’ was previously declared here
   86 |     void release() noexcept
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:86:10: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:130:10: error: type of ‘weak_release’ does not match original declaration [-Werror=lto-type-mismatch]
  130 |     void weak_release() // nothrow
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:100:10: note: ‘weak_release’ was previously declared here
  100 |     void weak_release() noexcept
      |          ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:100:10: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
../../../boost/smart_ptr/detail/sp_counted_base_gcc_atomic.hpp:97:18: error: type of ‘destroy’ does not match original declaration [-Werror=lto-type-mismatch]
   97 |     virtual void destroy() // nothrow
      |                  ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:65:18: note: ‘destroy’ was previously declared here
   65 |     virtual void destroy() noexcept // nothrow
      |                  ^
../../../boost/smart_ptr/detail/sp_counted_base_nt.hpp:65:18: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
lto1: some warnings being treated as errors
lto-wrapper: fatal error: /usr/bin/x86_64-pc-linux-gnu-g++ returned 1 exit status
compilation terminated.
/usr/lib/gcc/x86_64-pc-linux-gnu/14/../../../../x86_64-pc-linux-gnu/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status
...skipped <p../../../bin.v2/libs/smart_ptr/test/abi_test_nt_mt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden>abi_test_nt_mt.run for lack of <p../../../bin.v2/libs/smart_ptr/test/abi_test_nt_mt.test/gcc-14.3/gentoorelease/x86_64/pch-off/threading-multi/visibility-hidden>abi_test_nt_mt...
common.mkdir ../../../bin.v2/libs/smart_ptr/test/get_deleter_test2_no_rtti.test/gcc-14.3

        mkdir -p "../../../bin.v2/libs/smart_ptr/test/get_deleter_test2_no_rtti.test/gcc-14.3"

Originally reported downstream: https://bugs.gentoo.org/956660
Full build log: build.log

[pdimov]

The ODR violation in this test is deliberate, because that's what is tested - whether a program that violates the ODR in this manner (inconsistently defining BOOST_DISABLE_THREADS in some translation units and not others) still works.