Build fails with LTO - Githubissues

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

Note 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:

make[2]: Entering directory '/var/tmp/portage/net-dialup/freeradius-client-1.1.7-r3/work/freeradius-client-1.1.7/lib'
/bin/sh ../libtool  --tag=CC   --mode=link x86_64-pc-linux-gnu-gcc  -pipe -march=native -fstack-protector-all -O2 -fdiagnostics-color=always -frecord-gcc-switches -flto=3 -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 -version-info 2:0:0 -Wl,-O1 -Wl,--as-needed -Wl,-z,pack-relative-relocs -flto=3 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -Wl,--defsym=__gentoo_check_ldflags__=0 -o libfreeradius-client.la -rpath /usr/lib64 buildreq.lo clientid.lo env.lo sendserver.lo avpair.lo config.lo dict.lo ip_util.lo log.lo util.lo rc-md5.lo md5.lo  -lcrypt -lnsl 
libtool: link: x86_64-pc-linux-gnu-gcc -shared  -fPIC -DPIC  .libs/buildreq.o .libs/clientid.o .libs/env.o .libs/sendserver.o .libs/avpair.o .libs/config.o .libs/dict.o .libs/ip_util.o .libs/log.o .libs/util.o .libs/rc-md5.o .libs/md5.o   -Wl,--as-needed -lcrypt -lnsl  -march=native -fstack-protector-all -O2 -fdiagnostics-color=always -frecord-gcc-switches -flto=3 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -Werror=format-security -Werror=implicit-function-declaration -Werror=implicit-int -Werror=int-conversion -Werror=incompatible-pointer-types -Wl,-O1 -Wl,-z -Wl,pack-relative-relocs -flto=3 -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -Wl,--defsym=__gentoo_check_ldflags__=0   -Wl,-soname -Wl,libfreeradius-client.so.2 -o .libs/libfreeradius-client.so.2.0.0
../include/freeradius-client.h:524:6: error: type of 'rc_md5_calc' does not match original declaration [-Werror=lto-type-mismatch]
  524 | void rc_md5_calc(unsigned char *, unsigned char const *, unsigned int);
      |      ^
rc-md5.c:15:6: note: type mismatch in parameter 3
   15 | void rc_md5_calc(unsigned char *output, unsigned char const *input,
      |      ^
rc-md5.c:15:6: note: type 'size_t' should match type 'unsigned int'
rc-md5.c:15:6: note: 'rc_md5_calc' was previously declared here
rc-md5.c:15:6: note: code may be misoptimized unless '-fno-strict-aliasing' is used
lto1: some warnings being treated as errors
lto-wrapper: fatal error: x86_64-pc-linux-gnu-gcc returned 1 exit status
compilation terminated.
/usr/libexec/gcc/x86_64-pc-linux-gnu/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:444: libfreeradius-client.la] Error 1
make[2]: Leaving directory '/var/tmp/portage/net-dialup/freeradius-client-1.1.7-r3/work/freeradius-client-1.1.7/lib'
make[1]: *** [Makefile:427: all-recursive] Error 1
make: *** [Makefile:359: all] Error 2

Originally reported downstream: https://bugs.gentoo.org/927175 Full build log: build.log

Indeed, if we look at the current versions of the affected code, we see they are untruthful and disagree with each other: https://github.com/FreeRADIUS/freeradius-client/blob/79d92afb6baca62b7c27bf938034cf212459cf4d/lib/rc-md5.c#L20-L21 https://github.com/FreeRADIUS/freeradius-client/blob/79d92afb6baca62b7c27bf938034cf212459cf4d/include/freeradius-client.h#L544

FreeRADIUS / freeradius-client

Build fails with LTO #128