alexeyr marked an inline comment as done.
alexeyr added inline comments.

================
Comment at: 
clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp:114
   if (P.a[X++] != P.a[X++]) return 1;
+  if (X && X++ && X) return 1;
 
----------------
alexeyr wrote:
> aaron.ballman wrote:
> > alexeyr wrote:
> > > aaron.ballman wrote:
> > > > What do you think about the following?
> > > > ```
> > > > bool foo(int&);
> > > > bool bar();
> > > > 
> > > > int i;
> > > > if (foo(i) && bar() && foo(i)) return 1;
> > > > ```
> > > > I think that this should not be warned on (under the assumption that 
> > > > the reference variable can be modified by the call and thus may or may 
> > > > not be duplicate), but didn't see a test covering it.
> > > > 
> > > > It also brings up an interesting question about what to do if those 
> > > > were non-const pointers rather than references, because the data being 
> > > > pointed to could be modified as well.
> > > > 
> > > > (If you think this should be done separately from this review, that's 
> > > > totally fine by me, it looks like it would be an issue with the 
> > > > original code as well.)
> > > > 
> > > > One thing that is missing from this review are tests for the overloaded 
> > > > operator functionality.
> > > This is actually handled correctly, by the same logic as `(X && X++ && 
> > > X)`, so I don't think it needs a separate test. The drawback is that:
> > > 
> > > 1. it's too conservative, `X && bar() && X` isn't warned on either, 
> > > because I don't know a way to check that `bar()` doesn't have side 
> > > effects //on `X`// and so just test `HasSideEffects` 
> > > (https://stackoverflow.com/questions/60035219/check-which-variables-can-be-side-effected-by-expression-evaluation-in-clang-ast).
> > > 
> > > 2. the original code does have the same issue and I didn't fix it, so 
> > > `foo(X) && foo(X)` and `X++ && X++` do get a warning. 
> > > 
> > > I'll add overloaded operator tests.
> > Okay, that seems reasonable to me, thank you!
> I've added the tests (which uncovered a problem not limited to overloaded 
> operators; I needed to skip uninteresting nodes when looking at parents as 
> well).
Do you have any insight on https://reviews.llvm.org/D73775#1851553?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73775/new/

https://reviews.llvm.org/D73775



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