[clang] [analyzer][CTU] Macro expansions for imported translation units (PR #176126)

[Vladimir Vuksanovic via cfe-commits]

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@@ -1222,6 +1223,9 @@ bool ASTUnit::Parse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
   if (!Act->BeginSourceFile(*Clang, Clang->getFrontendOpts().Inputs[0]))
     return true;
 
+  if (OnCompilerCreated)
+    OnCompilerCreated(*Clang);
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vvuksanovic wrote:

There are a couple of alternatives to that. We should be able to pass the `MacroExpansionContext` here instead of the callback function, though that exposes that class in `ASTUnit`. Technically, we only need to pass the preprocessor instance in the callback.

I agree that exposing the compiler instance this way can allow the callback to modify it in some unexpected/problematic way which is not ideal. Looking through all parameters of `CreateASTUnitFromCommandLine` I couldn't find any option that would allow us to register the `MacroExpansionContext`.

https://github.com/llvm/llvm-project/pull/176126