[clang] [clang-tools-extra] [clang][modules] Remove `Module::ASTFile` (PR #185994)

[Ben Langmuir via cfe-commits]

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@@ -3500,17 +3501,23 @@ ASTReader::ReadControlBlock(ModuleFile &F,
       if (!IsImportingStdCXXModule) {
         StoredSize = (off_t)Record[Idx++];
         StoredModTime = (time_t)Record[Idx++];
+        ModuleCacheLen = (unsigned)Record[Idx++];
 
         StringRef SignatureBytes = Blob.substr(0, ASTFileSignature::size);
         StoredSignature = ASTFileSignature::create(SignatureBytes.begin(),
                                                    SignatureBytes.end());
         Blob = Blob.substr(ASTFileSignature::size);
 
-        // Use BaseDirectoryAsWritten to ensure we use the same path in the
-        // ModuleCache as when writing.
-        StoredFile = ReadPathBlob(BaseDirectoryAsWritten, Record, Idx, Blob);
+        StoredFile = ReadStringBlob(Record, Idx, Blob);
         if (ImportedFile.empty()) {
-          ImportedFile = StoredFile;
+          if (ImportedKind == MK_ImplicitModule) {
+            assert(ModuleCacheLen != 0);
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benlangmuir wrote:

Is module cache always absolute or would zero be valid if it was the current directory?

https://github.com/llvm/llvm-project/pull/185994