[clang] [clang][modules] Remove `ModuleManager` in-memory buffers (PR #194753)

[Ben Langmuir via cfe-commits]

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@@ -98,16 +100,38 @@ class ModuleFileKey {
 /// other types of module files, this is just the file system path.
 class ModuleFileName {
   std::string Path;
-  unsigned ImplicitModuleSuffixLength = 0;
+  /// The kind of the module file.
+  ///   0 in-memory
+  ///   1 explicit
+  ///   2+ implicit; the value denotes the length of the implicit module file
+  ///      path suffix that follows the module cache directory path in \c Path
+  unsigned Kind;
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benlangmuir wrote:

Maybe `KindOrSuffixLength` or similar. It would also be nice to define named constants for 0, 1, and the minimum suffix length so we aren't hard coding them in multiple places. Or maybe just make a real enum?

https://github.com/llvm/llvm-project/pull/194753