[libc-commits] [libc] [libc][startup] set --target= for linker when cross compiling (PR #96342)

[LLVM Continuous Integration via libc-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `libc-aarch64-ubuntu-fullbuild-dbg` running on `libc-aarch64-ubuntu` while building `libc` at step 4 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/71/builds/541

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)
...
-- Performing Test HAVE_GNU_POSIX_REGEX -- failed to compile
-- Performing Test HAVE_POSIX_REGEX -- success
-- Performing Test HAVE_STEADY_CLOCK -- success
-- Performing Test HAVE_PTHREAD_AFFINITY -- failed to compile
-- Configuring done
-- Generating done
-- Build files have been written to: /home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/build
@@@BUILD_STEP build libc@@@
Running: ninja libc
[1/1] Linking CXX executable projects/libc/startup/linux/crt1.o
FAILED: projects/libc/startup/linux/crt1.o 
: && /usr/bin/clang++ -fPIC -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 -r -nostdlib --target= projects/libc/startup/linux/aarch64/CMakeFiles/libc.startup.linux.aarch64.start.dir/start.cpp.o projects/libc/startup/linux/aarch64/CMakeFiles/libc.startup.linux.aarch64.tls.dir/tls.cpp.o projects/libc/startup/linux/CMakeFiles/libc.startup.linux.do_start.dir/do_start.cpp.o -o projects/libc/startup/linux/crt1.o   && :
clang: error: unable to execute command: Executable "g++" doesn't exist!
clang: error: linker (via gcc) command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
['ninja', 'libc'] exited with return code 1.
The build step threw an exception...
Traceback (most recent call last):
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 163, in step
    yield
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 120, in main
    run_command(['ninja', 'libc'])
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 178, in run_command
    util.report_run_cmd(cmd, cwd=directory)
  File "/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-zorg/zorg/buildbot/builders/annotated/util.py", line 49, in report_run_cmd
    subprocess.check_call(cmd, shell=shell, *args, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 190, in check_call
    raise CalledProcessError(retcode, cmd)
CalledProcessError: Command '['ninja', 'libc']' returned non-zero exit status 1
@@@STEP_FAILURE@@@
@@@BUILD_STEP build libc-startup@@@
Running: ninja libc-startup
[1/1] Linking CXX executable projects/libc/startup/linux/crt1.o
FAILED: projects/libc/startup/linux/crt1.o 
: && /usr/bin/clang++ -fPIC -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 -r -nostdlib --target= projects/libc/startup/linux/aarch64/CMakeFiles/libc.startup.linux.aarch64.start.dir/start.cpp.o projects/libc/startup/linux/aarch64/CMakeFiles/libc.startup.linux.aarch64.tls.dir/tls.cpp.o projects/libc/startup/linux/CMakeFiles/libc.startup.linux.do_start.dir/do_start.cpp.o -o projects/libc/startup/linux/crt1.o   && :
clang: error: unable to execute command: Executable "g++" doesn't exist!
clang: error: linker (via gcc) command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
['ninja', 'libc-startup'] exited with return code 1.
The build step threw an exception...
Traceback (most recent call last):
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 163, in step
    yield
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 124, in main
    run_command(['ninja', 'libc-startup'])
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 178, in run_command
    util.report_run_cmd(cmd, cwd=directory)
  File "/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-zorg/zorg/buildbot/builders/annotated/util.py", line 49, in report_run_cmd
    subprocess.check_call(cmd, shell=shell, *args, **kwargs)

```

https://github.com/llvm/llvm-project/pull/96342