[Bug]: Missing symbol when compiling 32-bit monolithic shared libs with lld-link (MSVC-like)

[hukeyue]

Describe the issue

All definitions defined by ABSL_INTERNAL_C_SYMBOL are not found by lld-link

$ninja abseil_dll

lld-link: error: <root>: undefined symbol: __AbslContainerInternalSampleEverything
lld-link: error: <root>: undefined symbol: __AbslInternalMutexYield
lld-link: error: <root>: undefined symbol: __AbslInternalOnFatalLogMessage
lld-link: error: <root>: undefined symbol: __AbslInternalPerThreadSemInit
lld-link: error: <root>: undefined symbol: __AbslInternalPerThreadSemPoke
lld-link: error: <root>: undefined symbol: __AbslInternalPerThreadSemPost
lld-link: error: <root>: undefined symbol: __AbslInternalPerThreadSemWait
lld-link: error: <root>: undefined symbol: __AbslInternalSleepFor
lld-link: error: <root>: undefined symbol: __AbslInternalSpinLockDelay
lld-link: error: <root>: undefined symbol: __AbslInternalSpinLockWake
lld-link: error: <root>: undefined symbol: __AbslInternalTraceContinue
lld-link: error: <root>: undefined symbol: __AbslInternalTraceObserved
lld-link: error: <root>: undefined symbol: __AbslInternalTraceSignal
lld-link: error: <root>: undefined symbol: __AbslInternalTraceWait
lld-link: error: <root>: undefined symbol: ____local_stdio_printf_options
lld-link: error: <root>: undefined symbol: __fprintf
lld-link: error: <root>: undefined symbol: __snprintf

cmake command are like

LLVM_PATH=$HOME/clang+llvm-22.1.3-arm64-apple-darwin20.1.0
cmake -G Ninja \
   -DCMAKE_CXX_STANDARD=20 -DCMAKE_CXX_STANDARD_REQUIRED=on \
   -DABSL_ENABLE_INSTALL=off \
   -DBUILD_SHARED_LIBS=on \
   -DABSL_MSVC_STATIC_RUNTIME=off \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_TOOLCHAIN_FILE=$HOME/vstoolchain/cmake/platforms/WinMsvc.cmake \
   -DHOST_ARCH=$WITH_CPU \
   -DCMAKE_RC_COMPILER=$HOME/vstoolchain/llvm-rc \
   -DCMAKE_MT=$HOME/vstoolchain/llvm-mt \
   -DCMAKE_NM=$HOME/vstoolchain/llvm-nm \
   -DLLVM_NATIVE_TOOLCHAIN=$LLVM_PATH \
   "-DMSVC_BASE=$HOME/vstoolchain/VC/Tools/MSVC/14.50.35717" \
   "-DWINSDK_BASE=$HOME/vstoolchain/Windows Kits/10" \
   -DWINSDK_VER=10.0.26100.0 \
   ..

Steps to reproduce the problem

1. generate zip tarball with depot_tools' package_from_installed.py script, make sure you have visual studio 2026 installed.
2. cd $HOME && git clone https://github.com/hukeyue/vstoolchain
3. extract the zip from step1 into $HOME/vstoolchain
4. cd $HOME && git clone https://github.com/abseil/abseil-cpp
5. cd $HOME/vstoolchain && WITH_CPU=x86 ./build-abseil.sh
6. cd $HOME/abseil-cpp/build-msvc-x86-dynamic && ninja abseil_dll

What version of Abseil are you using?

04f3bc0

What operating system and version are you using?

macOS Darwin Kernel Version 25.4.0: Thu Mar 19 19:31:56 PDT 2026; root:xnu-12377.101.15~1/RELEASE_ARM64_T6030

What compiler and version are you using?

➜ ~ ~/clang+llvm-22.1.3-arm64-apple-darwin20.1.0/bin/clang -v
clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
Target: arm64-apple-darwin25.4.0
Thread model: posix
InstalledDir: /Users/keeyou/clang+llvm-22.1.3-arm64-apple-darwin20.1.0/bin

What build system are you using?

➜ ~ cmake --version
cmake version 4.3.1

CMake suite maintained and supported by Kitware (kitware.com/cmake).

Additional context

see https://chromium.googlesource.com/chromium/tools/depot_tools.git/+/refs/heads/main/win_toolchain/package_from_installed.py and https://github.com/hukeyue/vstoolchain/blob/master/build-abseil.sh

[hukeyue]

x64 build and arm64 build don't have such issue in cross-compiling msvc monolithic shared lib.

[hukeyue]

And those symbols are compiled like below (output of llvm-nm)

➜  build-msvc-x86-dynamic git:(master) ✗ ~/clang+llvm-22.1.3-arm64-apple-darwin20.1.0/bin/llvm-nm absl/CMakeFiles/abseil_dll.dir/base/internal/tracing.cc.obj
00000001 a @feat.00
00000000 T _AbslInternalTraceContinue
00000000 T _AbslInternalTraceObserved
00000000 T _AbslInternalTraceSignal
00000000 T _AbslInternalTraceWait

the command line of invoking clang-cl:

➜  build-msvc-x86-dynamic git:(master) ✗ ninja -t commands absl/CMakeFiles/abseil_dll.dir/base/internal/tracing.cc.obj
/Users/keeyou/clang+llvm-22.1.3-arm64-apple-darwin20.1.0/bin/clang-cl  /nologo -TP -DABSL_BUILD_DLL -DNOMINMAX -Dabseil_dll_EXPORTS -I/Users/keeyou/abseil-cpp -D_CRT_SECURE_NO_WARNINGS --target=i686-windows-msvc -imsvc /Users/keeyou/vstoolchain/VC/Tools/MSVC/14.50.35717/atlmfc/include -imsvc /Users/keeyou/vstoolchain/VC/Tools/MSVC/14.50.35717/include -imsvc "/Users/keeyou/vstoolchain/Windows Kits/10/Include/10.0.26100.0/ucrt" -imsvc "/Users/keeyou/vstoolchain/Windows Kits/10/Include/10.0.26100.0/shared" -imsvc "/Users/keeyou/vstoolchain/Windows Kits/10/Include/10.0.26100.0/um" -imsvc "/Users/keeyou/vstoolchain/Windows Kits/10/Include/10.0.26100.0/winrt" /O2 /Ob2 /DNDEBUG -std:c++20 -MD /W3 /DNOMINMAX /DWIN32_LEAN_AND_MEAN /D_CRT_SECURE_NO_WARNINGS /D_SCL_SECURE_NO_WARNINGS /D_ENABLE_EXTENDED_ALIGNED_STORAGE -Wmost -Wextra -Wc++98-compat-extra-semi -Wcast-qual -Wconversion -Wdeprecated-pragma -Wfloat-overflow-conversion -Wfloat-zero-conversion -Wfor-loop-analysis -Wformat-security -Wgnu-redeclared-enum -Winfinite-recursion -Winvalid-constexpr -Wliteral-conversion -Wmissing-declarations -Wnullability-completeness -Woverlength-strings -Wpointer-arith -Wself-assign -Wshadow-all -Wshorten-64-to-32 -Wsign-conversion -Wstring-conversion -Wtautological-overlap-compare -Wtautological-unsigned-zero-compare -Wthread-safety -Wundef -Wuninitialized -Wunreachable-code -Wunused-comparison -Wunused-local-typedefs -Wunused-result -Wvla -Wwrite-strings -Wno-float-conversion -Wno-implicit-float-conversion -Wno-implicit-int-float-conversion -Wno-unknown-warning-option -Wno-unused-command-line-argument -DNOMINMAX -clang:-MD -clang:-MTabsl/CMakeFiles/abseil_dll.dir/base/internal/tracing.cc.obj -clang:-MFabsl/CMakeFiles/abseil_dll.dir/base/internal/tracing.cc.obj.d /Foabsl/CMakeFiles/abseil_dll.dir/base/internal/tracing.cc.obj /Fdabsl/CMakeFiles/abseil_dll.dir/ -c -- /Users/keeyou/abseil-cpp/absl/base/internal/tracing.cc

[hukeyue]

The symbols are exported with leading underscore. (there is no dumpbin tool in macOS, let's just use llvm-nm for simplicity)

the linker demands double leading underscore.

the exports.def generated by cmake.

exports.def.zip

[hukeyue]

In my memory, in 32-bit windows build, c symbols are defined with extra underscore prefix while 64-bit doesn't.

Below is an example of linking different types of windows dll (linking 32-bit tcmalloc_minimal.dll and 64-bit one).

See https://github.com/gperftools/gperftools/blob/master/src/windows/patch_functions.cc#L126-L141

[hukeyue]

When I commented out CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS in absl/copts/AbseilConfigureCopts.cmake, it compiled but without any export symbol.