[clang] [clang] Store size & mtime in in-memory module cache (PR #190207)

[Jan Svoboda via cfe-commits]

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@@ -28,16 +28,24 @@ namespace clang {
 /// each \a ModuleManager sees the same files.
 class InMemoryModuleCache : public llvm::RefCountedBase<InMemoryModuleCache> {
   struct PCM {
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jansvoboda11 wrote:

`Size`/`ModTime` will always be populated, except for stdin where `ModTime` will be zero. You're right that `InMemoryModuleCache` is only useful for implicit modules, but it is being used for explicit modules too, so it made sense to unify the semantics and always store the size and modification time regardless.

https://github.com/llvm/llvm-project/pull/190207