[clang] [Clang] Fix handling of references to variable templates with an empty argument list (PR #191154)

[via cfe-commits]

github-actions[bot] wrote:

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

* 50410 tests passed
* 1052 tests skipped

All executed tests passed, but another part of the build **failed**. Click on a failure below to see the details.

<details>
<summary>[code=4294967295] tools/clang/tools/extra/unittests/clang-doc/ClangDocTests.exe</summary>

```
FAILED: [code=4294967295] tools/clang/tools/extra/unittests/clang-doc/ClangDocTests.exe
C:\Windows\system32\cmd.exe /C "cd . && C:\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe -E vs_link_exe --msvc-ver=1944 --intdir=tools\clang\tools\extra\unittests\clang-doc\CMakeFiles\ClangDocTests.dir --rc="C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\x64\rc.exe" --mt="C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\x64\mt.exe" --manifests  -- C:\clang\clang-msvc\bin\lld-link.exe /nologo @CMakeFiles\ClangDocTests.rsp  /out:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.exe /implib:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.lib /pdb:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.pdb /version:0.0 /MANIFEST:NO /STACK:10000000 /INCREMENTAL:NO /subsystem:console && cd ."
LINK: command "C:\clang\clang-msvc\bin\lld-link.exe /nologo @CMakeFiles\ClangDocTests.rsp /out:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.exe /implib:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.lib /pdb:tools\clang\tools\extra\unittests\clang-doc\ClangDocTests.pdb /version:0.0 /MANIFEST:NO /STACK:10000000 /INCREMENTAL:NO /subsystem:console" failed (exit code 1) with the following output:
lld-link: error: undefined symbol: void __cdecl clang::ParseAST(class clang::Sema &, bool, bool)
>>> referenced by clangFrontend.lib(FrontendAction.cpp.obj):(protected: virtual void __cdecl clang::ASTFrontendAction::ExecuteAction(void))
>>> referenced by clangFrontend.lib(ChainedIncludesSource.cpp.obj):(class llvm::IntrusiveRefCntPtr<class clang::ExternalSemaSource> __cdecl clang::createChainedIncludesSource(class clang::CompilerInstance &, class llvm::IntrusiveRefCntPtr<class clang::ASTReader> &))

lld-link: error: undefined symbol: void __cdecl clang::hlsl::HandleRootSignatureTarget(class clang::Sema &, class llvm::StringRef)
>>> referenced by clangFrontend.lib(FrontendActions.cpp.obj):(protected: virtual void __cdecl clang::HLSLFrontendAction::ExecuteAction(void))

lld-link: error: undefined symbol: class clang::IdentifierInfo * __cdecl clang::hlsl::ParseHLSLRootSignature(class clang::Sema &, enum llvm::dxbc::RootSignatureVersion, class clang::StringLiteral *)
>>> referenced by clangFrontend.lib(FrontendActions.cpp.obj):(public: virtual void __cdecl InjectRootSignatureCallback::MacroDefined(class clang::Token const &, class clang::MacroDirective const *))
```
</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/191154