[PATCH] D64762: [AST] Treat semantic form of InitListExpr as implicit code in traversals

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov added inline comments.


================
Comment at: clang/include/clang/AST/RecursiveASTVisitor.h:2332
       S->isSemanticForm() ? S->getSyntacticForm() : S, Queue));
   TRY_TO(TraverseSynOrSemInitListExpr(
       S->isSemanticForm() ? S : S->getSemanticForm(), Queue));
----------------
gribozavr wrote:
> Instead of adding a whole new if statement, could you wrap the second existing TRY_TO in `if(shouldVisitImplicitCode())` ?
Despite looking very similar, that would **not** be equivalent to the current version.

For most init lists (that do not have alternative "form"), the following invariants hold:
```
InitList* E = ...;
assert(E->isSemanticForm());
assert(E->isSyntacticForm()); 
assert(E->getSynacticForm() == nullptr);
```

This subtle fact means the current code does not traversed the list twice if they do not have an alternative form (either semantic or syntactic).

Now, if we only run the first statement, we will call `TraverseSynOrSemInitListExpr(S->getSyntacticForm())` and `S->getSyntacticForm()` returns `null`. So we don't traverse anything.

I tried various ways to keep both calls, but they all ended up being too complicated, hence the final version. Let me know if you see a better way to address this.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64762/new/

https://reviews.llvm.org/D64762