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

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith added inline comments.


================
Comment at: clang/lib/Sema/SemaLookup.cpp:623
 
-  Decls.set_size(N);
+  Decls.truncate(N);
 
----------------
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.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115386/new/

https://reviews.llvm.org/D115386