[libc-commits] [libc] [libc] mbrtowc implementation (PR #144760)

[LLVM Continuous Integration via libc-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `libc-x86_64-debian-gcc-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/131/builds/24439

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 4 (annotate) failure: 'python ../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py ...' (failure)
...
[52/82] Generating header sys/statvfs.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/sys/statvfs.yaml
[53/82] Generating header sys/types.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/sys/types.yaml
[54/80] Generating header termios.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/termios.yaml
[55/69] Generating header poll.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/poll.yaml
[56/69] Generating header uchar.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/uchar.yaml
[57/69] Generating header sys/wait.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/sys/wait.yaml
[58/66] Generating header sys/socket.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/sys/socket.yaml
[59/64] Generating header wchar.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/wchar.yaml
[60/64] Generating header math.h from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/runtimes/../libc/include/math.yaml
[61/64] Building CXX object libc/src/wchar/CMakeFiles/libc.src.wchar.mbrtowc.dir/mbrtowc.cpp.o
FAILED: libc/src/wchar/CMakeFiles/libc.src.wchar.mbrtowc.dir/mbrtowc.cpp.o 
/usr/bin/g++ -DLIBC_NAMESPACE=__llvm_libc_20_0_0_git -D_DEBUG -I/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc -isystem /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/build/libc/include -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -Wimplicit-fallthrough -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -DLIBC_QSORT_IMPL=LIBC_QSORT_QUICK_SORT -DLIBC_ADD_NULL_CHECKS -DLIBC_ERRNO_MODE=LIBC_ERRNO_MODE_DEFAULT -fpie -ffreestanding -DLIBC_FULL_BUILD -isystem/usr/lib/gcc/x86_64-linux-gnu/12//include -nostdinc -idirafter/usr/include -fno-builtin -fno-exceptions -fno-lax-vector-conversions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -ftrivial-auto-var-init=pattern -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Wall -Wextra -Werror -Wconversion -Wno-sign-conversion -Wdeprecated -fext-numeric-literals -Wno-pedantic -Wimplicit-fallthrough -Wwrite-strings -Wextra-semi -DLIBC_COPT_PUBLIC_PACKAGING -std=gnu++17 -MD -MT libc/src/wchar/CMakeFiles/libc.src.wchar.mbrtowc.dir/mbrtowc.cpp.o -MF libc/src/wchar/CMakeFiles/libc.src.wchar.mbrtowc.dir/mbrtowc.cpp.o.d -o libc/src/wchar/CMakeFiles/libc.src.wchar.mbrtowc.dir/mbrtowc.cpp.o -c /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/src/wchar/mbrtowc.cpp
In file included from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/src/wchar/mbrtowc.h:12,
                 from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/src/wchar/mbrtowc.cpp:9:
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/hdr/types/mbstate_t.h:18:8: error: missing terminating " character [-Werror]
   18 | #error "Cannot overlay mbstate_t
      |        ^
cc1plus: all warnings being treated as errors
[62/64] Building CXX object libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.mbrtowc.dir/mbrtowc.cpp.o
FAILED: libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.mbrtowc.dir/mbrtowc.cpp.o 
/usr/bin/g++ -DLIBC_NAMESPACE=__llvm_libc_20_0_0_git -D_DEBUG -I/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc -isystem /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/build/libc/include -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -Wimplicit-fallthrough -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g -DLIBC_QSORT_IMPL=LIBC_QSORT_QUICK_SORT -DLIBC_ADD_NULL_CHECKS -DLIBC_ERRNO_MODE=LIBC_ERRNO_MODE_DEFAULT -fpie -ffreestanding -DLIBC_FULL_BUILD -isystem/usr/lib/gcc/x86_64-linux-gnu/12//include -nostdinc -idirafter/usr/include -fno-builtin -fno-exceptions -fno-lax-vector-conversions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -ftrivial-auto-var-init=pattern -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Wall -Wextra -Werror -Wconversion -Wno-sign-conversion -Wdeprecated -fext-numeric-literals -Wno-pedantic -Wimplicit-fallthrough -Wwrite-strings -Wextra-semi -std=gnu++17 -MD -MT libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.mbrtowc.dir/mbrtowc.cpp.o -MF libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.mbrtowc.dir/mbrtowc.cpp.o.d -o libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.mbrtowc.dir/mbrtowc.cpp.o -c /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/src/__support/wchar/mbrtowc.cpp
In file included from /home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/src/__support/wchar/mbrtowc.cpp:10:
/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/llvm-project/libc/hdr/types/mbstate_t.h:18:8: error: missing terminating " character [-Werror]
   18 | #error "Cannot overlay mbstate_t
      |        ^
cc1plus: all warnings being treated as errors
[63/64] Building CXX object libc/src/__support/wchar/CMakeFiles/libc.src.__support.wchar.character_converter.dir/character_converter.cpp.o
ninja: build stopped: subcommand failed.
['ninja', 'libc'] exited with return code 1.
The build step threw an exception...
Traceback (most recent call last):
  File "/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/build/../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 176, in step
    yield
  File "/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/build/../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 138, in main
    run_command(['ninja', 'libc'])
  File "/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-fullbuild-dbg/build/../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 191, in run_command
    util.report_run_cmd(cmd, cwd=directory)
  File "/home/llvm-libc-buildbot/buildbot-worker/libc-x86_64-debian-fullbuild/libc-x86_64-debian-gcc-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/python3.11/subprocess.py", line 413, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['ninja', 'libc']' returned non-zero exit status 1.
@@@STEP_FAILURE@@@
@@@BUILD_STEP build libc-startup@@@
Running: ninja libc-startup
ninja: no work to do.
@@@BUILD_STEP libc-unit-tests@@@
Running: ninja libc-unit-tests

```

</details>

https://github.com/llvm/llvm-project/pull/144760