librados: disable symbol versions when building statically

When building internal libraries statically with `-DENABLE_SHARED=no`,
linking `librados.a` always fails because the
`LIBRADOS_C_API_DEFAULT_F` macro inserts an underscore prefix to all
exported symbols.  It does this so a versioned symbol with the real
name can be created.  Symbol versions however only work with shared
libraries, and the linker fails to find the prefix-less symbols:

 FAILED: bin/ceph_radosacl
 : && /usr/bin/c++ -O0 -fPIC -fuse-ld=mold -Og -g -rdynamic src/tools/CMakeFiles/ceph_radosacl.dir/radosacl.cc.o -o bin/ceph_radosacl  -Wl,-rpath,:::::::::::::::::::::::::::::::  lib/liblibrados.a  lib/libglobal.a  lib/liblibrados_impl.a  lib/libosdc.a  lib/libcls_lock_client.a  lib/libceph-common.a  /usr/lib/aarch64-linux-gnu/libblkid.so  /usr/lib/aarch64-linux-gnu/libcrypto.so  lib/libjson_spirit.a  lib/libcommon_utf8.a  lib/libextblkdev.a  -lcap  boost/lib/libboost_thread.a  boost/lib/libboost_chrono.a  boost/lib/libboost_atomic.a  boost/lib/libboost_system.a  boost/lib/libboost_random.a  boost/lib/libboost_program_options.a  boost/lib/libboost_date_time.a  boost/lib/libboost_iostreams.a  boost/lib/libboost_regex.a  lib/libfmtd.a  lib/liberasure_code.a  /usr/lib/aarch64-linux-gnu/libudev.so  /usr/lib/aarch64-linux-gnu/libz.so  -ldl  /usr/lib/aarch64-linux-gnu/librt.a  -lresolv   -Wl,--as-needed -latomic && :
 mold: error: undefined symbol: rados_conf_parse_env
 >>> referenced by librados_cxx.cc
 >>>               lib/liblibrados.a(librados_cxx.cc.o):(librados::v14_2_0::Rados::conf_parse_env(char const*) const)
 mold: error: undefined symbol: rados_nobjects_list_seek
 >>> referenced by librados_cxx.cc
 >>>               lib/liblibrados.a(librados_cxx.cc.o):(librados::NObjectIteratorImpl::seek(unsigned int))
 mold: error: undefined symbol: rados_conf_parse_argv_remainder
 >>> referenced by librados_cxx.cc
 >>>               lib/liblibrados.a(librados_cxx.cc.o):(librados::v14_2_0::Rados::conf_parse_argv_remainder(int, char const**, char const**) const)
 mold: error: undefined symbol: rados_version
 >>> referenced by librados_cxx.cc
 >>>               lib/liblibrados.a(librados_cxx.cc.o):(librados::v14_2_0::Rados::version(int*, int*, int*))
 mold: error: undefined symbol: rados_nobjects_list_next2
 >>> referenced by librados_c.cc
 >>>               lib/liblibrados.a(librados_c.cc.o):(_rados_nobjects_list_next)
 >>> referenced by librados_cxx.cc
 >>>               lib/liblibrados.a(librados_cxx.cc.o):(librados::NObjectIteratorImpl::get_next())

Signed-off-by: Max Kellermann <[email protected]>

Author: MaxKellermann

src/librados/CMakeLists.txt

@@ -29,6 +29,7 @@ if(ENABLE_SHARED)
     set_property(TARGET librados APPEND_STRING PROPERTY
       LINK_FLAGS " -static-libstdc++ -static-libgcc")
   endif()
+  target_compile_definitions(librados PRIVATE -DLIBRADOS_SHARED=1)
 endif()
 target_link_libraries(librados PRIVATE
   librados_impl osdc ceph-common cls_lock_client

src/librados/librados_c.cc

@@ -44,7 +44,7 @@
 #define tracepoint(...)
 #endif
 
-#if defined(HAVE_ASM_SYMVER) || defined(HAVE_ATTR_SYMVER)
+#if defined(LIBRADOS_SHARED) && (defined(HAVE_ASM_SYMVER) || defined(HAVE_ATTR_SYMVER))
 // prefer __attribute__() over global asm(".symver"). because the latter
 // is not parsed by the compiler and is partitioned away by GCC if
 // lto-partitions is enabled, in other words, these asm() statements