[clang] [llvm] [clang][ScanDeps] Allow PCHs to have different VFS overlays (PR #82294)

[Michael Spencer via cfe-commits]

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@@ -67,7 +68,7 @@ static bool checkHeaderSearchPaths(const HeaderSearchOptions &HSOpts,
   if (LangOpts.Modules) {
     if (HSOpts.VFSOverlayFiles != ExistingHSOpts.VFSOverlayFiles) {
       if (Diags) {
-        Diags->Report(diag::err_pch_vfsoverlay_mismatch);
+        Diags->Report(diag::warn_pch_vfsoverlay_mismatch);
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Bigcheese wrote:

Maybe, this is currently disabled by default, but is useful for normal PCH too. It would be an issue if we ever want to start changing the original command lines too though (to increase cache hits for normal TUs), there you only want to warn when scanning, not in the actual build.

https://github.com/llvm/llvm-project/pull/82294