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

[Cyndy Ishida 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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cyndyishida wrote:

Can Size/ModTime ever stay null for the lifetime of `PCM` saved in `InMemoryModuleCache`? My assumption is no, because this documentation states this is only used for implicit module builds, but the logic in `ModuleManager::addModule` can trigger when resolving explicit modules which do not rely on `ModTime`, so I am unsure.

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