Hi,
I met a problem with variable ac_link, it does not work in some condition.
in configure.ac, there is a line: AC_CHECK_FUNCS(xdr_uint32
xdr_uint32_t xdr_u_int32_t)
And here is ac_link:
ac_ext=c
ac_cpp='$CPP $CPPFLAGS'
ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS
conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
In my build env, that is ""
from glibc 2.27 rpc support is dropped, so linked to -ltirpc. And I
expect that xdr_uint32_t is found,
ac_cv_func_xdr_uint32_t=yes. but during configure, I got
ac_cv_func_xdr_uint32_t=no.
According to gcc doc,
https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html, the link order
will influence
link result. As I understand, according to this doc, function
xdr_uint32_t in conftest.c cannot be loaded
since -ltirpc is before conftest.c.
So I tried "gcc conftest.c -o conftest -ltirpc", then it works well,
and contest can be generated.
gcc -v:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
10.3.0-1ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2
--prefix=/usr --with-gcc-major-version-only --program-suffix=-10
--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-bootstrap --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 --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-10-gDeRY6/gcc-10-10.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-gDeRY6/gcc-10-10.3.0/debian/tmp-gcn/usr,hsa
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.3.0 (Ubuntu 10.3.0-1ubuntu1)
And idea how to reslove above problem?
Another confuse problem is in my another build environment, which gcc
is different, AC_CHECK_FUNCS
works well no matter -ltirpc is before or after conftest.c.
Thanks.
