[libc-commits] [libc] libc: Remove `extern "C"` from main declarations (PR #102825)

[LLVM Continuous Integration via libc-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `libc-x86_64-debian-fullbuild-dbg` running on `libc-x86_64-debian-fullbuild` while building `libc` at step 4 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/179/builds/3987

Here is the relevant piece of the build log for the reference:
```
Step 4 (annotate) failure: 'python ../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py ...' (failure)
...
[21/99] Building CXX object projects/libc/test/integration/src/pthread/CMakeFiles/libc.test.integration.src.pthread.pthread_once_test.__build__.dir/pthread_once_test.cpp.o
[22/99] Building CXX object projects/libc/test/integration/src/threads/CMakeFiles/libc.test.integration.src.threads.call_once_test.__build__.dir/call_once_test.cpp.o
[23/99] Building CXX object projects/libc/test/integration/src/threads/CMakeFiles/libc.test.integration.src.threads.cnd_test.__build__.dir/cnd_test.cpp.o
[24/99] Building CXX object projects/libc/test/integration/src/unistd/CMakeFiles/libc.test.integration.src.unistd.getcwd_test.__build__.dir/getcwd_test.cpp.o
[25/99] Building CXX object projects/libc/test/integration/src/unistd/CMakeFiles/libc.test.integration.src.unistd.execv_test.__build__.dir/execv_test.cpp.o
[26/99] Building CXX object projects/libc/test/integration/src/unistd/CMakeFiles/libc.test.integration.src.unistd.execve_test.__build__.dir/execve_test.cpp.o
[27/99] Building CXX object projects/libc/test/integration/src/unistd/CMakeFiles/libc.test.integration.src.unistd.fork_test.__build__.dir/fork_test.cpp.o
[28/99] Building CXX object projects/libc/test/integration/src/spawn/CMakeFiles/libc.test.integration.src.spawn.posix_spawn_test.__build__.dir/posix_spawn_test.cpp.o
[29/99] Building CXX object projects/libc/test/integration/src/__support/threads/CMakeFiles/libc.test.integration.src.__support.threads.thread_tls_test.__build__.dir/thread_tls_test.cpp.o
[30/99] Linking CXX executable projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_envp_test.__build__
FAILED: projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_envp_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/startup/linux/CMakeFiles/libc.test.integration.startup.linux.startup_no_envp_test.__build__.dir/main_without_envp.cpp.o -o projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_envp_test.__build__  projects/libc/test/integration/startup/linux/liblibc.test.integration.startup.linux.startup_no_envp_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[31/99] Linking CXX executable projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_args_test.__build__
FAILED: projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_args_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/startup/linux/CMakeFiles/libc.test.integration.startup.linux.startup_no_args_test.__build__.dir/main_without_args.cpp.o -o projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_no_args_test.__build__  projects/libc/test/integration/startup/linux/liblibc.test.integration.startup.linux.startup_no_args_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[32/99] Linking CXX executable projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_tls_test.__build__
[33/99] Linking CXX executable projects/libc/test/integration/src/stdlib/libc.test.integration.src.stdlib.getenv_test.__build__
[34/99] Linking CXX executable projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.startup_args_test.__build__
[35/99] Linking CXX executable projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.init_fini_array_test.__build__
FAILED: projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.init_fini_array_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/startup/linux/CMakeFiles/libc.test.integration.startup.linux.init_fini_array_test.__build__.dir/init_fini_array_test.cpp.o -o projects/libc/test/integration/startup/linux/libc.test.integration.startup.linux.init_fini_array_test.__build__  projects/libc/test/integration/startup/linux/liblibc.test.integration.startup.linux.init_fini_array_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[36/99] Linking CXX executable projects/libc/test/integration/src/stdio/libc.test.integration.src.stdio.sprintf_size_test_no_sprintf.__build__
[37/99] Linking CXX executable projects/libc/test/integration/src/pthread/libc.test.integration.src.pthread.pthread_equal_test.__build__
FAILED: projects/libc/test/integration/src/pthread/libc.test.integration.src.pthread.pthread_equal_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/src/pthread/CMakeFiles/libc.test.integration.src.pthread.pthread_equal_test.__build__.dir/pthread_equal_test.cpp.o -o projects/libc/test/integration/src/pthread/libc.test.integration.src.pthread.pthread_equal_test.__build__  projects/libc/test/integration/src/pthread/liblibc.test.integration.src.pthread.pthread_equal_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[38/99] Linking CXX executable projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_test.__build__
FAILED: projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/src/threads/CMakeFiles/libc.test.integration.src.threads.thrd_test.__build__.dir/thrd_test.cpp.o -o projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_test.__build__  projects/libc/test/integration/src/threads/liblibc.test.integration.src.threads.thrd_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[39/99] Linking CXX executable projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_exit_test.__build__
FAILED: projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_exit_test.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -nolibc -nostartfiles -nostdlib++ -static projects/libc/startup/linux/crt1.o projects/libc/test/IntegrationTest/CMakeFiles/libc.test.IntegrationTest.test.dir/test.cpp.o projects/libc/test/integration/src/threads/CMakeFiles/libc.test.integration.src.threads.thrd_exit_test.__build__.dir/thrd_exit_test.cpp.o -o projects/libc/test/integration/src/threads/libc.test.integration.src.threads.thrd_exit_test.__build__  projects/libc/test/integration/src/threads/liblibc.test.integration.src.threads.thrd_exit_test.libc.a && :
/usr/bin/ld: projects/libc/startup/linux/crt1.o: in function `__llvm_libc_19_0_0_git::do_start()':
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-fullbuild-dbg/llvm-project/libc/startup/linux/do_start.cpp:147: undefined reference to `main(int, char**, char**)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

```

https://github.com/llvm/llvm-project/pull/102825