<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/63613>63613</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            libcxx to wasm32 fails to build with `error: unknown type name '__BEGIN_DECLS'`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++,
            build-problem
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          sylvestre
      </td>
    </tr>
</table>

<pre>
    ```

/opt/sccache//sccache /build/source/build-llvm/tools/clang/stage2-bins/bin/clang++ --target=wasm32-unknown-wasi -DLIBCXX_BUILDING_LIBCXXABI -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LIBCPP_BUILDING_LIBRARY -D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER -D_LIBCPP_REMOVE_TRANSITIVE_INCLUDES -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/build/source/libcxx/src -I/build/source/build-wasm/libcxx-wasm32-wasi/include/c++/v1 -I/build/source/libcxxabi/include -O2 -DNDEBUG -g1 -fstack-protector-strong -Wformat -Werror=format-security -Wno-unused-command-line-argument -Wdate-time -D_FORTIFY_SOURCE=2 -fno-stack-protector -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -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 -ffunction-sections -fdata-sections -std=c++20 -faligned-allocation -nostdinc++ -fvisibility-inlines-hidden -fvisibility=hidden -Wall -Wextra -Wnewline-eof -Wshadow -Wwrite-strings -Wno-unused-parameter -Wno-long-long -Werror=return-type -Wextra-semi -Wundef -Wunused-template -Wformat-nonliteral -Wno-user-defined-literals -Wno-covered-switch-default -Wno-suggest-override -Wno-error -fno-exceptions -MD -MT libcxx/src/CMakeFiles/cxx_static.dir/filesystem/filesystem_clock.cpp.o -MF libcxx/src/CMakeFiles/cxx_static.dir/filesystem/filesystem_clock.cpp.o.d -o libcxx/src/CMakeFiles/cxx_static.dir/filesystem/filesystem_clock.cpp.o -c /build/source/libcxx/src/filesystem/filesystem_clock.cpp
In file included from /build/source/libcxx/src/filesystem/filesystem_clock.cpp:14:
In file included from /build/source/libcxx/src/filesystem/posix_compat.h:42:
/usr/include/sys/statvfs.h:47:1: error: unknown type name '__BEGIN_DECLS'
   47 | __BEGIN_DECLS
      | ^
/usr/include/sys/statvfs.h:53:6: error: expected function body after function declarator
   53 |      __THROW __nonnull ((1, 2));
      | ^
/usr/include/sys/statvfs.h:74:6: error: expected function body after function declarator
   74 |      __THROW __nonnull ((2));
      | ^
/usr/include/sys/statvfs.h:88:1: error: unknown type name '__END_DECLS'
   88 | __END_DECLS
      | ^
```
</pre>
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