[clang] [clang][driver][clang-cl] Fix unused argument warning for `/std:c++20` for precompiled module inputs to `clang-cl` (PR #99300)

[Sharadh Rajaraman via cfe-commits]

https://github.com/sharadhr updated https://github.com/llvm/llvm-project/pull/99300

>From 51e74869c87de8ed8b37e7a9391428f3dfc1ac1a Mon Sep 17 00:00:00 2001
From: Sharadh Rajaraman <r.sharadh at outlook.sg>
Date: Sun, 14 Jul 2024 11:05:57 +0100
Subject: [PATCH 1/3] `TY_ModuleFile` should be a 'CXX' file type

---
 clang/lib/Driver/Types.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index a7b6b9000e1d2b..c6a03f4491dd79 100644
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -242,7 +242,7 @@ 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:

>From 3b9c3d251bbbfd44b0d7d900d795343b0e4fa474 Mon Sep 17 00:00:00 2001
From: Sharadh Rajaraman <3754080+sharadhr at users.noreply.github.com>
Date: Tue, 16 Jul 2024 20:10:12 +0100
Subject: [PATCH 2/3] Resolve `clang-format` issues

---
 clang/lib/Driver/Types.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index c6a03f4491dd79..2b9b391c19c9fd 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_ModuleFile:
+  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:

>From f1d83d67b0cc72c4f55cd96e654ed9e9962b48a5 Mon Sep 17 00:00:00 2001
From: Sharadh Rajaraman <r.sharadh at outlook.sg>
Date: Wed, 7 Aug 2024 20:41:39 +0100
Subject: [PATCH 3/3] Add a test to check that warning is gone

---
 clang/test/Driver/cl-cxx20-modules.cppm | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/clang/test/Driver/cl-cxx20-modules.cppm b/clang/test/Driver/cl-cxx20-modules.cppm
index 06df929c42342f..fd1d3ba05a422b 100644
--- a/clang/test/Driver/cl-cxx20-modules.cppm
+++ b/clang/test/Driver/cl-cxx20-modules.cppm
@@ -1,3 +1,6 @@
+// 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
 
@@ -6,3 +9,8 @@
 
 // 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]
\ No newline at end of file