[PATCH] D78652: [clang-tidy] Suppress reports to similarly used parameters in 'bugprone-easily-swappable-parameters'

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman accepted this revision.
aaron.ballman added a comment.
This revision is now accepted and ready to land.

LGTM once the optional bits are fixed up.



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Comment at: clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp:529
+/// ReturnStmts return them from the function.
+class Returned {
+  llvm::SmallVector<const ParmVarDecl *, SmallDataStructureSize> ReturnedParams;
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whisperity wrote:
> whisperity wrote:
> > aaron.ballman wrote:
> > > Question: would it make sense to (someday, not now) consider output parameters similar to return statements? e.g.,
> > > ```
> > > void int_swap(int &foo, int &bar) {
> > >   int temp = foo;
> > >   foo = bar;
> > >   bar = temp;
> > > }
> > > ```
> > > As a question for today: should `co_return` should be handled similarly as `return`?
> > 1. Maybe. Unfortunately, one needs to be careful with that. Originally I did implement a "5th" heuristic that dealt with ignoring parameters that had the same builtin operator used on them. However, while it silenced a few false positives, it started creating **massive** amounts of false negatives.
> > (In the concrete example, I think `foo = bar` will silence them because //"appears in the same expression"//.)
> > 
> > 2. I don't know. It would require a deeper understanding of Coroutines themselves, and how people use them.
> If you don't mind me posting images, I can show a direct example. Things where the inability to track data flow really bites us in the backside.
> 
> Examples from Apache Xerces:
> 
> Here's a false positive that would be silenced by the logic of //"using the same operateur on the two params"//.
> {F15891567}
> 
> And here is a false negative from the exact same logic.
> {F15891568}
> 
> Maybe it could be //some// solace that we're restricting to non-const-lvalue-references (and pointers-to-non-const ??) and only assignment (**only** assignment?!))...
Ah, point #1 is an excellent point. As for #2, I think we can handle it in a follow-up, but I believe `co_return` follows the same usage patterns as `return`, generally.


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Comment at: clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp:563-566
+  llvm::Optional<relatedness_heuristic::AppearsInSameExpr> SameExpr;
+  llvm::Optional<relatedness_heuristic::PassedToSameFunction> PassToFun;
+  llvm::Optional<relatedness_heuristic::AccessedSameMemberOf> SameMember;
+  llvm::Optional<relatedness_heuristic::Returned> Returns;
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whisperity wrote:
> aaron.ballman wrote:
> > I don't think there's a need to make these optional when we're using the `Enabled` flag.
> The original idea was that each heuristic could be individually toggled by the user... But I think we can agree that would be a bad idea and just overengineering.
Yeah, I think it's probably better to drop the optionals here -- we can revisit the decision later if there's user feedback requesting finer granularity here.


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  https://reviews.llvm.org/D78652/new/

https://reviews.llvm.org/D78652