[PATCH] D31757: [clang-tidy] Add a clang-tidy check for possible inefficient vector operations

Aaron Ballman via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Thu Apr 13 13:54:49 PDT 2017

aaron.ballman added inline comments.

Comment at: clang-tidy/performance/InefficientVectorOperationCheck.cpp:95-96
+    const MatchFinder::MatchResult &Result) {
+  if (Result.Context->getDiagnostics().hasUncompilableErrorOccurred())
+    return;
hokein wrote:
> aaron.ballman wrote:
> > We don't usually add this test in to our check calls; why are you adding it here?
> It will prevent some unexpected things happened when the translation unit fails to compile.
> We had a few experiences before. We encountered some misbehavior of some checks (e.g. https://reviews.llvm.org/rL294578) with a non-compilable TU, and then we added this statement to avoid the misbehavior.
I think that this should be moved up into whatever layer calls check(), because it does not seem like the checks are actually valid if the TU has had a fatal error. However, that doesn't have to be part of this patch.

Comment at: clang-tidy/performance/InefficientVectorOperationCheck.cpp:109-111
+  auto AllVectorVarRefs = utils::decl_ref_expr::allDeclRefExprs(
+      *VectorVarDecl, *LoopParent, *Result.Context);
+  for (const auto *Ref : AllVectorVarRefs) {
aaron.ballman wrote:
> I'm not certain what types are being used here. Can you turn `AllVectorVarRefs` into something with an explicit type so that I can know what `Ref`'s type is?
I may not have been clear -- I don't mean that the variable name should contain type information, I mean that the type should not be automatically deduced. We only use `auto` when the type is spelled explicitly in the initialization or is otherwise obvious from context (like range-based for loops).


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