[clang] [lldb] Serialize `#pragma redefine_extname` into precompiled headers. (PR #186755)

[Chuanqi Xu via cfe-commits]

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@@ -6061,6 +6059,22 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema *SemaPtr, StringRef isysroot,
     }
   }
 
+  // Write the set of #pragma redefine_extname'd, undeclared identifiers. We
+  // always write the entire table, since later PCH files in a PCH chain are
+  // only interested in the results at the end of the chain.
+  RecordData ExtnameUndeclaredIdentifiers;
+  if (SemaPtr) {
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ChuanqiXu9 wrote:

> Isn't the goal of C++20 modules that eventually every #include should become a module?

No ...

> Modules also propagate macros, of course. 

No. C++20 Named Modules won't propagate macros for sure. Otherwise it is not ISO Named modules.


https://github.com/llvm/llvm-project/pull/186755