[clang][driver][clang-cl] Fix unused argument warning for /std:c++20 for precompiled module inputs to clang-cl

[sharadhr]

Relates to #98761: -fmodule-file requires /std:c++20 or greater, but passing that option results in an unused argument warning. This resolves that.

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[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Sharadh Rajaraman (sharadhr)

Changes

Relates to #98761: -fmodule-file requires /std:c++20 or greater, but passing that option results in an unused argument warning. This resolves that.

---

Full diff: https://github.com/llvm/llvm-project/pull/99300.diff

1 Files Affected:

• (modified) clang/lib/Driver/Types.cpp (+3-1)

diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index a7b6b9000e1d2..842eb59b7382d 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:

[ChuanqiXu9]

Please add a test for this too. We can use any file ends with .pcm to mimic module file in the Driver's test and we can use CHECK-NOT: to filter the warning.

[sharadhr]

Not quite sure how to handle the test for this; I'm struggling to find a .pcm file that can be used.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[ChuanqiXu9]

Maybe something like this:

// RUN: rm -rf %t
// RUN: split-file %s %t
// RUN: %clang %t/fake.pcm -std=c++20 -### 2>&1 | FileCheck %t/fake.pcm

//--- fake.pcm
// CHECK-NOT: warning

[ChuanqiXu9]

LGTM

[github-actions]

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[ChuanqiXu9]

/cherry-pick 9d315bc

[llvmbot]

Failed to cherry-pick: 9d315bc

https://github.com/llvm/llvm-project/actions/runs/10294654014

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

[ChuanqiXu9]

From the log, it looks like the git crashes instead of conflicts. @tru would you like to take look.

@sharadhr also if you want to backport this to 19.x, maybe you can try to create a PR to the branch of 19.x branch manually in case the automated cherry-pick doesn't work.

[sharadhr]

Just to clarify—you'd like me to open another PR to release/19.X? I can do that.

In fact I'm a little more ambitious because this and #98761 are honestly very simple PRs—I'd like them to be backported as far as Clang 16 (which is when modules support first appeared) if possible.

[ChuanqiXu9]

Just to clarify—you'd like me to open another PR to release/19.X? I can do that.

Yes. You can find the automated generated example in #102159

In fact I'm a little more ambitious because this and #98761 are honestly very simple PRs—I'd like them to be backported as far as Clang 16 (which is when modules support first appeared) if possible.

No, this is not possible. We may never have new releases for 18, 17 and 16 as far as I know.

[sharadhr]

Ah. That's a pity but no problem. I'll create the PR now. Thanks!