[PATCH] D115386: AST: Avoid using SmallVector::set_size() in UnresolvedSet

[David Blaikie via Phabricator via cfe-commits]

dblaikie accepted this revision.
dblaikie added a comment.
This revision is now accepted and ready to land.

Looks good.



================
Comment at: clang/lib/Sema/SemaLookup.cpp:623
 
-  Decls.set_size(N);
+  Decls.truncate(N);
 
----------------
dexonsmith wrote:
> Two things to confirm here.
> 
> First is that the destructors are trivial. From clang/include/clang/AST/DeclAccessPair.h:
> ```
> lang=c++
> class DeclAccessPair {
>   uintptr_t Ptr; // we'd use llvm::PointerUnion, but it isn't trivial
> ```
> (If they hadn't been trivial, then hypothetically there could been other code somewhere that ran the destructors later...)
> 
> Second is that `set_size()` was only used for truncation. I confirmed that that three ways:
> - Looking backward, `N` starts as `Decls.size()` and the only changes are decrement operatoers.
> - Looking forward, there's no code that would initialize / assign to the new member (so if it increased size, it would likely have led to problems elsewhere).
> - Tests pass.
Thanks for the details!


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  https://reviews.llvm.org/D115386/new/

https://reviews.llvm.org/D115386