Static linking GameNetworkingSockets using vcpkg/CMake dynamically links to OS abseil libraries

[jclc]

I'm trying to statically link the dependencies to my project using vcpkg but for some reason when linking target_link_libraries(main PRIVATE GameNetworkingSockets::static) it ends up linking with the OS absl shared objects:

$ ldd build/main
        linux-vdso.so.1 (0x00007f825ddca000)
        libprotobuf.so.35.1.0 => /usr/lib/libprotobuf.so.35.1.0 (0x00007f825d000000)
        libutf8_validity.so.35.1.0 => /usr/lib/libutf8_validity.so.35.1.0 (0x00007f825dd8c000)
        libcrypto.so.3 => /usr/lib/libcrypto.so.3 (0x00007f825c800000)
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007f825c400000)
        libm.so.6 => /usr/lib/libm.so.6 (0x00007f825dc85000)
        libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007f825dc50000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007f825c000000)
        /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007f825ddcc000)
        libz.so.1 => /usr/lib/libz.so.1 (0x00007f825d5c4000)
        libabsl_die_if_null.so.2605.0.0 => /usr/lib/libabsl_die_if_null.so.2605.0.0 (0x00007f825dc49000)
        libabsl_statusor.so.2605.0.0 => /usr/lib/libabsl_statusor.so.2605.0.0 (0x00007f825d5be000)
        libabsl_log_internal_check_op.so.2605.0.0 => /usr/lib/libabsl_log_internal_check_op.so.2605.0.0 (0x00007f825d5b4000)
        libabsl_log_internal_conditions.so.2605.0.0 => /usr/lib/libabsl_log_internal_conditions.so.2605.0.0 (0x00007f825d5af000)
        libabsl_log_internal_message.so.2605.0.0 => /usr/lib/libabsl_log_internal_message.so.2605.0.0 (0x00007f825d5a0000)
        libabsl_log_internal_nullguard.so.2605.0.0 => /usr/lib/libabsl_log_internal_nullguard.so.2605.0.0 (0x00007f825d59b000)
        libabsl_raw_hash_set.so.2605.0.0 => /usr/lib/libabsl_raw_hash_set.so.2605.0.0 (0x00007f825d592000)
        libabsl_status.so.2605.0.0 => /usr/lib/libabsl_status.so.2605.0.0 (0x00007f825d586000)
        libabsl_cord.so.2605.0.0 => /usr/lib/libabsl_cord.so.2605.0.0 (0x00007f825d56d000)
        libabsl_cordz_info.so.2605.0.0 => /usr/lib/libabsl_cordz_info.so.2605.0.0 (0x00007f825d564000)
        libabsl_cord_internal.so.2605.0.0 => /usr/lib/libabsl_cord_internal.so.2605.0.0 (0x00007f825d556000)
        libabsl_hash.so.2605.0.0 => /usr/lib/libabsl_hash.so.2605.0.0 (0x00007f825d551000)
        libabsl_synchronization.so.2605.0.0 => /usr/lib/libabsl_synchronization.so.2605.0.0 (0x00007f825d53f000)
        libabsl_time.so.2605.0.0 => /usr/lib/libabsl_time.so.2605.0.0 (0x00007f825d52b000)
        libabsl_time_zone.so.2605.0.0 => /usr/lib/libabsl_time_zone.so.2605.0.0 (0x00007f825cfe5000)
        libabsl_str_format_internal.so.2605.0.0 => /usr/lib/libabsl_str_format_internal.so.2605.0.0 (0x00007f825cfc6000)
        libabsl_strings.so.2605.0.0 => /usr/lib/libabsl_strings.so.2605.0.0 (0x00007f825cfa0000)
        libabsl_spinlock_wait.so.2605.0.0 => /usr/lib/libabsl_spinlock_wait.so.2605.0.0 (0x00007f825d524000)
        libabsl_throw_delegate.so.2605.0.0 => /usr/lib/libabsl_throw_delegate.so.2605.0.0 (0x00007f825cf9a000)
        libabsl_raw_logging_internal.so.2605.0.0 => /usr/lib/libabsl_raw_logging_internal.so.2605.0.0 (0x00007f825d51f000)
        libbrotlienc.so.1 => /usr/lib/libbrotlienc.so.1 (0x00007f825c306000)
        libbrotlidec.so.1 => /usr/lib/libbrotlidec.so.1 (0x00007f825cf88000)
        libzstd.so.1 => /usr/lib/libzstd.so.1 (0x00007f825be9f000)
        libabsl_base.so.2605.0.0 => /usr/lib/libabsl_base.so.2605.0.0 (0x00007f825cf82000)
        libabsl_leak_check.so.2605.0.0 => /usr/lib/libabsl_leak_check.so.2605.0.0 (0x00007f825cf7d000)
        libabsl_examine_stack.so.2605.0.0 => /usr/lib/libabsl_examine_stack.so.2605.0.0 (0x00007f825cf76000)
        libabsl_log_internal_format.so.2605.0.0 => /usr/lib/libabsl_log_internal_format.so.2605.0.0 (0x00007f825cf71000)
        libabsl_log_internal_structured_proto.so.2605.0.0 => /usr/lib/libabsl_log_internal_structured_proto.so.2605.0.0 (0x00007f825cf6c000)
        libabsl_strerror.so.2605.0.0 => /usr/lib/libabsl_strerror.so.2605.0.0 (0x00007f825cf67000)
        libabsl_log_internal_log_sink_set.so.2605.0.0 => /usr/lib/libabsl_log_internal_log_sink_set.so.2605.0.0 (0x00007f825cf61000)
        libabsl_log_internal_globals.so.2605.0.0 => /usr/lib/libabsl_log_internal_globals.so.2605.0.0 (0x00007f825cf5a000)
        libabsl_log_globals.so.2605.0.0 => /usr/lib/libabsl_log_globals.so.2605.0.0 (0x00007f825cf54000)
        libabsl_log_internal_proto.so.2605.0.0 => /usr/lib/libabsl_log_internal_proto.so.2605.0.0 (0x00007f825cf4f000)
        libabsl_strings_internal.so.2605.0.0 => /usr/lib/libabsl_strings_internal.so.2605.0.0 (0x00007f825cf49000)
        libabsl_hashtablez_sampler.so.2605.0.0 => /usr/lib/libabsl_hashtablez_sampler.so.2605.0.0 (0x00007f825cf43000)
        libabsl_crc_cord_state.so.2605.0.0 => /usr/lib/libabsl_crc_cord_state.so.2605.0.0 (0x00007f825cf3a000)
        libabsl_cordz_functions.so.2605.0.0 => /usr/lib/libabsl_cordz_functions.so.2605.0.0 (0x00007f825cf35000)
        libabsl_cordz_handle.so.2605.0.0 => /usr/lib/libabsl_cordz_handle.so.2605.0.0 (0x00007f825cf30000)
        libabsl_stacktrace.so.2605.0.0 => /usr/lib/libabsl_stacktrace.so.2605.0.0 (0x00007f825cf2b000)
        libabsl_city.so.2605.0.0 => /usr/lib/libabsl_city.so.2605.0.0 (0x00007f825cf26000)
        libabsl_kernel_timeout_internal.so.2605.0.0 => /usr/lib/libabsl_kernel_timeout_internal.so.2605.0.0 (0x00007f825cf1f000)
        libabsl_tracing_internal.so.2605.0.0 => /usr/lib/libabsl_tracing_internal.so.2605.0.0 (0x00007f825cf1a000)
        libabsl_malloc_internal.so.2605.0.0 => /usr/lib/libabsl_malloc_internal.so.2605.0.0 (0x00007f825cf13000)
        libabsl_int128.so.2605.0.0 => /usr/lib/libabsl_int128.so.2605.0.0 (0x00007f825cf0b000)
        libbrotlicommon.so.1 => /usr/lib/libbrotlicommon.so.1 (0x00007f825cee8000)
        libabsl_symbolize.so.2605.0.0 => /usr/lib/libabsl_symbolize.so.2605.0.0 (0x00007f825cede000)
        libabsl_log_sink.so.2605.0.0 => /usr/lib/libabsl_log_sink.so.2605.0.0 (0x00007f825ced9000)
        libabsl_crc32c.so.2605.0.0 => /usr/lib/libabsl_crc32c.so.2605.0.0 (0x00007f825ced2000)
        libabsl_exponential_biased.so.2605.0.0 => /usr/lib/libabsl_exponential_biased.so.2605.0.0 (0x00007f825cecd000)
        libabsl_debugging_internal.so.2605.0.0 => /usr/lib/libabsl_debugging_internal.so.2605.0.0 (0x00007f825cec4000)
        libabsl_demangle_internal.so.2605.0.0 => /usr/lib/libabsl_demangle_internal.so.2605.0.0 (0x00007f825ceb7000)
        libabsl_crc_internal.so.2605.0.0 => /usr/lib/libabsl_crc_internal.so.2605.0.0 (0x00007f825cead000)
        libabsl_crc_cpu_detect.so.2605.0.0 => /usr/lib/libabsl_crc_cpu_detect.so.2605.0.0 (0x00007f825cea8000)
        libabsl_demangle_rust.so.2605.0.0 => /usr/lib/libabsl_demangle_rust.so.2605.0.0 (0x00007f825cea0000)
        libabsl_decode_rust_punycode.so.2605.0.0 => /usr/lib/libabsl_decode_rust_punycode.so.2605.0.0 (0x00007f825c7f9000)
        libabsl_utf8_for_code_point.so.2605.0.0 => /usr/lib/libabsl_utf8_for_code_point.so.2605.0.0 (0x00007f825c7f4000)

For the record I am also including abseil for some container types in my project, but if I remove GameNetworkingSockets abseil is statically linked. Even when I link protobuf::libprotobuf directly I don't have the same issue, this only seems to happen when using the GNS vcpkg package.

CMakeLists.txt:

// project ...
set(CMAKE_CXX_STANDARD 23)

find_package(Stb REQUIRED)
find_package(fmt REQUIRED)
find_package(glm REQUIRED)
find_package(spdlog REQUIRED)
find_package(imgui REQUIRED)
find_package(absl REQUIRED)
find_package(flatbuffers REQUIRED)
find_package(SDL3 REQUIRED)
find_package(GameNetworkingSockets REQUIRED)
find_package(EnTT REQUIRED)

// add_executable ...

target_link_libraries(main PRIVATE Threads::Threads)
target_link_libraries(main PRIVATE fmt::fmt)
target_link_libraries(main PRIVATE SDL3::SDL3)
target_link_libraries(main PRIVATE absl::flat_hash_map)
target_link_libraries(main PRIVATE flatbuffers::flatbuffers)
target_link_libraries(main PRIVATE glm::glm)
target_link_libraries(main PRIVATE imgui::imgui)
target_link_libraries(main PRIVATE spdlog::spdlog)
target_link_libraries(main PRIVATE GameNetworkingSockets::static)

[zpostfacto]

"GameNetworkingSockets::static" only selects the static version of GameNetworkingSockets itself. It does not necessarily mean that every transitive dependency will also be linked statically.

That said, your "ldd" output shows that this is not specific to Abseil. You are also getting the system shared versions of protobuf, OpenSSL, zlib, zstd, and Brotli. In particular:

libprotobuf.so.35.1.0 => /usr/lib/libprotobuf.so.35.1.0
libcrypto.so.3 => /usr/lib/libcrypto.so.3

The Abseil shared libraries are most likely being pulled in transitively by that system protobuf library.

Since you are using vcpkg and apparently expect a statically linked dependency graph, I suspect CMake is mixing the vcpkg GNS package with dependencies found under "/usr/lib". This can happen because of a stale CMake cache, the vcpkg toolchain not being active during the initial configure, or package search variables such as "Protobuf_DIR" resolving to the system installation.

Could you please provide:

1. The vcpkg triplet you are using.
2. The complete CMake configure command.
3. The relevant values from "CMakeCache.txt":

grep -E '^(Protobuf|protobuf|absl|OPENSSL|VCPKG).*=' build/CMakeCache.txt

Also, please try configuring from a completely empty build directory and building with verbose output:

rm -rf build

cmake -S . -B build
-DCMAKE_TOOLCHAIN_FILE="$VCPKG_ROOT/scripts/buildsystems/vcpkg.cmake"
-DVCPKG_TARGET_TRIPLET=

cmake --build build --verbose

The verbose linker command should make it clear which package is adding "/usr/lib/libprotobuf.so".

I do not think the presence of shared transitive dependencies is inherently a bug in the "GameNetworkingSockets::static" target. However, if a clean build using a static vcpkg triplet still causes GNS to select the system protobuf package instead of the vcpkg one, then there may be a problem with the exported GNS CMake package or the vcpkg port.

[jclc]

Okay, I feel a little stupid now... There must have been some outdated cached artifacts since a fully clean build links as it should. Sorry for wasting your time.