[PATCH] D13071: [PATCH] New checker for mismatched operator new/operator delete definitions

[Aaron Ballman via cfe-commits]

On Mon, Sep 28, 2015 at 12:36 PM, Alexander Kornienko via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
> alexfh added inline comments.
>
> ================
> Comment at: clang-tidy/misc/NewDeleteOverloadsCheck.cpp:170
> @@ +169,3 @@
> +    const auto &OI = std::find_if(
> +        Overloads.begin(), Overloads.end(), [&](const FunctionDecl *FD) {
> +          if (FD == O)
> ----------------
> aaron.ballman wrote:
>> alexfh wrote:
>> > aaron.ballman wrote:
>> > > alexfh wrote:
>> > > > I just noticed that this will be an O(N^2) from all new/delete overloads in all classes in a TU. This should probably be not much usually, but I can imagine a corner-case, where this is going to be slooow. How about sharding these by the enclosing record declaration?
>> > > Yes, the O(N^2) is unfortunate, sorry for not calling that out explicitly. I figured that N should be incredibly minimal, however (especially since we only care about *written* overloads that are not placement overloads). So realistically, the maximum that N can be here is 6: operator new(), operator new[](), operator delete(), operator delete[](), and sized operator delete()/operator delete[](). I figured that this wasn't worth complicating the code over since N is bounded.
>> > >
>> > > But I suppose the worry is if you have these operators defined in a a lot of classes in the same TU? In that case, I suppose I could replace SmallVector<FunctionDecl *> Overloads with MapVector<CXXRecordDecl *, FunctionDecl *> Overloads?
>> > > But I suppose the worry is if you have these operators defined in a a lot of
>> > > classes in the same TU? In that case, I suppose I could replace
>> > > SmallVector<FunctionDecl *> Overloads with MapVector<CXXRecordDecl
>> > > *, FunctionDecl *> Overloads?
>> >
>> > Yes, this is what I meant. Though I didn't know about `MapVector<>` before you told me ;)
>> Er, not MapVector, but perhaps a std::map<CXXRecordDecl *, std::vector<FunctionDecl *>>, I guess.
> Might be a `DenseMap<CXXRecordDecl *, SmallVector<FunctionDecl *, 6>>` as well. Or `std::map<..., SmallVector<,>>`.

I wound up going with std::map and llvm::SmallVector. The values seem
too expensive for a DenseMap, but the lists should definitely be
small.

~Aaron

>
>
> http://reviews.llvm.org/D13071
>
>
>
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