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

[via lldb-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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divVerent wrote:

>From what I understand yes, it remains necessary.

Either textual includes remain a thing, then it remains necessary to be able to make a module that has these pragmas a module, and still affect textual includes after it.

Or they go away, then it becomes a necessity to use this _within_ a module's implementation (which then will likely consist of other modules), or else the "large autogenerated file that does all the symbol renaming" can't be a module on its own and we still have to #include it.

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