[clang] [Lexer] Prevent hitting the file system for ASTReader tokens (PR #192492)

[Vassil Vassilev via cfe-commits]

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@@ -0,0 +1,15 @@
+// RUN: rm -f %t.h %t.pch
+// RUN: echo "int variable_del_cern = 42;" > %t.h
+// RUN: %clang_cc1 -x c++-header -emit-pch -o %t.pch %t.h
+// RUN: rm %t.h
+// RUN: %clang_cc1 -fno-validate-pch -ast-dump -include-pch %t.pch %s
+
+// This test ensures that Clang does not access the filesystem when
+// handling SourceLocations originating from a PCH.
+//
+// After generating the PCH, the original header is removed. If Clang
+// attempts to access it (e.g. via MeasureTokenLength), the test will fail.
+
+int function() { 
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vgvassilev wrote:

Thanks for confirming!

https://github.com/llvm/llvm-project/pull/192492