[llvm-branch-commits] [clang] [clang][driver][clang-cl] Fix unused argument warning for `/std:c++20` for precompiled module inputs to `clang-cl` (PR #102438)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Sharadh Rajaraman (sharadhr)

<details>
<summary>Changes</summary>

Manual PR to backport #<!-- -->99300. 

---
Full diff: https://github.com/llvm/llvm-project/pull/102438.diff


2 Files Affected:

- (modified) clang/lib/Driver/Types.cpp (+3-1) 
- (added) clang/test/Driver/cl-cxx20-modules.cppm (+16) 


``````````diff
diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index a7b6b9000e1d2..2b9b391c19c9f 100644
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -242,7 +242,9 @@ bool types::isCXX(ID Id) {
   case TY_CXXHUHeader:
   case TY_PP_CXXHeaderUnit:
   case TY_ObjCXXHeader: case TY_PP_ObjCXXHeader:
-  case TY_CXXModule: case TY_PP_CXXModule:
+  case TY_CXXModule:
+  case TY_PP_CXXModule:
+  case TY_ModuleFile:
   case TY_PP_CLCXX:
   case TY_CUDA: case TY_PP_CUDA: case TY_CUDA_DEVICE:
   case TY_HIP:
diff --git a/clang/test/Driver/cl-cxx20-modules.cppm b/clang/test/Driver/cl-cxx20-modules.cppm
new file mode 100644
index 0000000000000..43dbf517485a0
--- /dev/null
+++ b/clang/test/Driver/cl-cxx20-modules.cppm
@@ -0,0 +1,16 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cl /std:c++20 --precompile -### -- %s 2>&1 | FileCheck --check-prefix=PRECOMPILE %s
+// PRECOMPILE: -emit-module-interface
+
+// RUN: %clang_cl /std:c++20 --fmodule-file=Foo=Foo.pcm -### -- %s 2>&1 | FileCheck --check-prefix=FMODULEFILE %s
+// FMODULEFILE: -fmodule-file=Foo=Foo.pcm
+
+// RUN: %clang_cl /std:c++20 --fprebuilt-module-path=. -### -- %s 2>&1 | FileCheck --check-prefix=FPREBUILT %s
+// FPREBUILT: -fprebuilt-module-path=.
+
+// RUN: %clang_cl %t/test.pcm /std:c++20 -### 2>&1 | FileCheck --check-prefix=CPP20WARNING %t/test.pcm
+
+//--- test.pcm
+// CPP20WARNING-NOT: clang-cl: warning: argument unused during compilation: '/std:c++20' [-Wunused-command-line-argument]

``````````

</details>


https://github.com/llvm/llvm-project/pull/102438