[native_toolchain_c] Fix Android c++_static not linking libc++abi#3241
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dcharkes merged 2 commits intodart-lang:mainfrom Mar 17, 2026
Merged
[native_toolchain_c] Fix Android c++_static not linking libc++abi#3241dcharkes merged 2 commits intodart-lang:mainfrom
dcharkes merged 2 commits intodart-lang:mainfrom
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On Android, let clang's driver handle C++ standard library linking instead of passing `-l c++_static` directly. This ensures both libc++_static.a and libc++abi.a are linked when statically linking the C++ standard library. When cppLinkStdLib is 'c++_static', pass `-static-libstdc++` to clang, which correctly expands to link both libraries. For the default c++_shared case, clang handles it automatically. Fixes dart-lang#3240
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On Android, use -Wl,-Bstatic/-Bdynamic to force static resolution of -lc++ when cppLinkStdLib is 'c++_static'. This picks up the NDK's libc++.a linker script which expands to INPUT(-lc++_static -lc++abi), ensuring libc++abi is also linked. Previously, -l c++_static was passed directly which only linked libc++_static.a but not libc++abi.a. This left C++ ABI symbols (typeinfo, vtables, RTTI) undefined, causing dlopen failures on newer Android versions with stricter linker namespace enforcement. Also adds a test that verifies the compiled shared library has no undefined C++ ABI symbols, and documents c++_static in the cppLinkStdLib API docs. Fixes dart-lang#3240
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dcharkes
approved these changes
Mar 17, 2026
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Summary
Fixes
cppLinkStdLib: 'c++_static'on Android not linkinglibc++abi, which causeddlopenfailures on newer Android versions with stricter linker namespace enforcement.Approach
Uses
-Wl,-Bstatic -lc++ -Wl,-Bdynamicinstead of-l c++_staticdirectly. This forces the linker to resolve-lc++using the NDK'slibc++.alinker script, which expands toINPUT(-lc++_static -lc++abi).-static-libstdc++turned out to not work because the Android NDK clang driver does not inject the C++ standard library during linking — it leaves that entirely to the build system.Changes
run_cbuilder.dart: Use-Wl,-Bstatic -lc++ -Wl,-BdynamicwhencppLinkStdLibisc++_staticon Androidctool.dart: Documentc++_staticin thecppLinkStdLibAPI docscbuilder_cross_android_test.dart: Add test that builds a C++ shared library usingstd::runtime_errorand verifies_ZTISt13runtime_erroris not an undefined symbolhelpers.dart: AddexpectSymbolNotUndefinedhelper reusingreadSymbolscxxabi.cc: Test source file that exercises libc++abi symbolsFixes #3240