[PATCH] D68634: [ASTImporter] Imported FunctionDecls inherit attributes from existing functions

Wed Oct 9 05:13:19 PDT 2019

martong added a comment.

In D68634#1701192 <https://reviews.llvm.org/D68634#1701192>, @martong wrote:

> In D68634#1700591 <https://reviews.llvm.org/D68634#1700591>, @a_sidorin wrote:
>
> > Hello Balasz,
> >  In my opinion, importing and setting the attributes should be handled by the stuff used in InitializeImportedDecl(). Can we extend it or reuse the code? It will allow us not to miss the required actions while importing a new function too.
>
>
> I was thinking about that too, but it turned out to be a way more intrusive change.
>
> We have to work with the most recent existing decl (`PrevDecl`) of the FunctionDecl whose attribute we currently import.
>  We can get the `PrevDecl` only with the help of the lookup. We can't get it from the `ToD` param of `InitializeImportedDecl` because by the time when we call `InitializeImportedDecl` the redecl chain is not connected. So, we should pass `PrevDecl` then into `GetImportedOrCreateDecl`.  It would require to change all call expressions of `GetImportedOrCreateDecl` (58 occurences). Besides, we would use the `PrevDecl` only in case of inheritable attributes, only they require this special care. Note that there are a bunch of non-inheritable attributes which are already handled correctly in `InitializeImportedDecl`.

Actually, giving it some more thought, I realized it would make sense to pass the `PrevDecl` into `GetImportedOrCreateDecl` because that way we could connect the redecl chain right after the new node is created, and before importing any other node. That could facilitate structural eq check in the import of subsequent dependent nodes (see https://github.com/Ericsson/clang/issues/506).
Anyway, this change would be quite a big change compared to the original small patch we have here.

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https://reviews.llvm.org/D68634