[clang] Fix enum enumerator visibility loss when #include is between module imports (PR #188865)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 53424 tests passed
* 1043 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### Clang
<details>
<summary>Clang.PCH/cxx2a-compare.cpp</summary>

```
Exit Code: 70

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\clang.exe -cc1 -internal-isystem C:\_work\llvm-project\llvm-project\build\lib\clang\23\include -nostdsysteminc -pedantic-errors -std=c++2a -emit-pch  C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp -o C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\clang.exe' -cc1 -internal-isystem 'C:\_work\llvm-project\llvm-project\build\lib\clang\23\include' -nostdsysteminc -pedantic-errors -std=c++2a -emit-pch 'C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp' -o 'C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp'
# note: command had no output on stdout or stderr
# RUN: at line 2
c:\_work\llvm-project\llvm-project\build\bin\clang.exe -cc1 -internal-isystem C:\_work\llvm-project\llvm-project\build\lib\clang\23\include -nostdsysteminc -pedantic-errors -std=c++2a -include-pch C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp -verify C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\clang.exe' -cc1 -internal-isystem 'C:\_work\llvm-project\llvm-project\build\lib\clang\23\include' -nostdsysteminc -pedantic-errors -std=c++2a -include-pch 'C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp' -verify 'C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp'
# note: command had no output on stdout or stderr
# RUN: at line 3
c:\_work\llvm-project\llvm-project\build\bin\clang.exe -cc1 -internal-isystem C:\_work\llvm-project\llvm-project\build\lib\clang\23\include -nostdsysteminc -pedantic-errors -std=c++2a -include-pch C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp -emit-llvm C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp -o -
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\clang.exe' -cc1 -internal-isystem 'C:\_work\llvm-project\llvm-project\build\lib\clang\23\include' -nostdsysteminc -pedantic-errors -std=c++2a -include-pch 'C:\_work\llvm-project\llvm-project\build\tools\clang\test\PCH\Output\cxx2a-compare.cpp.tmp' -emit-llvm 'C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp' -o -
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
# | Stack dump:
# | 0.	Program arguments: c:\\_work\\llvm-project\\llvm-project\\build\\bin\\clang.exe -cc1 -internal-isystem C:\\_work\\llvm-project\\llvm-project\\build\\lib\\clang\\23\\include -nostdsysteminc -pedantic-errors -std=c++2a -include-pch C:\\_work\\llvm-project\\llvm-project\\build\\tools\\clang\\test\\PCH\\Output\\cxx2a-compare.cpp.tmp -emit-llvm C:\\_work\\llvm-project\\llvm-project\\clang\\test\\PCH\\cxx2a-compare.cpp -o -
# | 1.	<eof> parser at end of file
# | 2.	Per-file LLVM IR generation
# | 3.	C:\_work\llvm-project\llvm-project\clang\test\PCH\cxx2a-compare.cpp:14:13: Generating code for declaration 'bar'
# | Exception Code: 0xC0000005
# | fatal error: error in backend: IO sandbox violation
# `-----------------------------
# error: command failed with exit status: 70

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/188865