[cfe-dev] [llvm-dev] [SemaCXX] Should we fix test failing due to reverse iteration?

Richard Trieu via cfe-dev cfe-dev at lists.llvm.org
Thu Jun 1 21:41:18 PDT 2017


This is my old code.  I went ahead and fixed it in r304519.  Let me know if
there's any other trouble from it.

(To the mailing lists this time.)

On Thu, Jun 1, 2017 at 1:46 PM, Grang, Mandeep Singh via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I see that the following test fails if reverse iteration of SmallPtrSet is
> enabled:
>
> *clang/test/SemaCXX/warn-loop-analysis.cpp*
>
> This is because in SemaStmt.cpp we iterate SmallPtrSet and output warnings
> about the variables not used in the loop.
>
> Expected output: *warning: variables 'i', 'j', and 'k' used in loop
> condition not modified*
>
> Output with reverse iteration: *warning: variables 'k', 'j', and 'i' used
> in loop condition not*
>
> I would like the community's opinion on whether this is something worth
> fixing? In this case, should the output always be the same irrespective of
> the iteration order?
>
> If yes, then we have 2 alternatives:
>
> 1. Change SmallPtrSet to SmallVector for the container (VarDecls) being
> iterated - this may have a compile time impact (need to measure).
>
> 2. Sort the container (VarDecls) before iteration. We can sort based on
> decl source location and decl name. Not sure if these guaranteed to be
> unique?
>
> Thanks,
>
> Mandeep
>
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