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

[Haojian Wu via Phabricator via cfe-commits]

hokein added inline comments.


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Comment at: clang-tidy/performance/InefficientVectorOperationCheck.cpp:53-54
+                        PushBackCall)),
+          hasParent(compoundStmt(unless(has(ReserveCall)),
+                                 has(VectorVarDefStmt))))
+          .bind("for_loop"),
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aaron.ballman wrote:
> hokein wrote:
> > aaron.ballman wrote:
> > > I'm really not keen on this. It will catch trivial cases, so there is some utility, but this will quickly fall apart with anything past the trivial case.
> > The motivation of this check is to find code patterns like `for (int i = 0; i < n; ++i) { v.push_back(i); }` and clean them in our codebase (we have lots of similar cases). [These](https://docs.google.com/document/d/1Bbc-6DlNs6zQujWD5-XOHWbfPJVMG7Z_T27Kv0WcFb4/edit?usp=sharing) are all cases we want to support. Using `hasParent` is a simple and sufficient way to do it IMO.
> I'm not convinced of the utility without implementing this in a more sensitive way. Have you run this across any large code bases and found that it catches issues?
Yeah, the check catches ~2800 cases (regexp shows ~17,000 total usages) in our internal codebase. And all caught cases are what we are interested in. It would catch more if we support for-range loops and iterator-based for-loops. 


https://reviews.llvm.org/D31757