[clang] [LinkerWrapper] Use the correct empty file on Windows (PR #84322)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Joseph Huber (jhuber6)

<details>
<summary>Changes</summary>

Summary:
The clang-offload-bundler uses an empty file to control the bundles made
for embedding. Previously this still used `/dev/null` by mistake even on
Windows.


---
Full diff: https://github.com/llvm/llvm-project/pull/84322.diff


1 Files Affected:

- (modified) clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp (+4-1) 


``````````diff
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 576e8f2cd7f8fd..849b12e1e8c6fc 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -410,7 +410,10 @@ fatbinary(ArrayRef<std::pair<StringRef, StringRef>> InputFiles,
     Targets.push_back(Saver.save("hipv4-amdgcn-amd-amdhsa--" + Arch));
   CmdArgs.push_back(Saver.save(llvm::join(Targets, ",")));
 
-  CmdArgs.push_back("-input=/dev/null");
+  if (Triple.isOSWindows())
+    CmdArgs.push_back("-input=NUL");
+  else
+    CmdArgs.push_back("-input=/dev/null");
   for (const auto &[File, Arch] : InputFiles)
     CmdArgs.push_back(Saver.save("-input=" + File));
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/84322