[PATCH] D91037: [clang-tidy] Fix crash in bugprone-redundant-branch-condition on ExprWithCleanups

Aaron Ballman via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Thu Nov 12 09:48:41 PST 2020


aaron.ballman added inline comments.


================
Comment at: clang-tools-extra/test/clang-tidy/checkers/bugprone-redundant-branch-condition.cpp:1092
+      // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: redundant condition 'isSet' [bugprone-redundant-branch-condition]
+      // CHECK-FIXES: {{isSet}}
+    }
----------------
zinovy.nis wrote:
> aaron.ballman wrote:
> > zinovy.nis wrote:
> > > aaron.ballman wrote:
> > > > There's not a whole lot of context for FileCheck to determine if it's been correctly applied or not (same below) -- for instance, won't this pass even if no changes are applied because FileCheck is still going to find `isSet` in the file?
> > > Thanks. Fixed.
> > Maybe it's just early in the morning for me, but... I was expecting the transformation to be:
> > ```
> > if (RetT::Test(isSet).Ok() && isSet) {
> >   if (RetT::Test(isSet).Ok() && isSet) {
> >   }
> > }
> > ```
> > turns into
> > ```
> > if (RetT::Test(isSet).Ok() && isSet) {
> > }
> > ```
> > Why does it remove the `&& isSet` instead? That seems like it's changing the logic here from `if (true && false)` to `if (true)`.
> IMO it's correct.
> `isSet` cannot change its value between `if`s while `RetT::Test(isSet).Ok()` can.
> So we don't need to re-evaluate `isSet` and need to re-evaluate `RetT::Test(isSet).Ok()` only.
> 
> 
> 
> > That seems like it's changing the logic here from if (true && false) to if (true).
> 
> 
> As I understand only the second `if` is transformed.
Does this only trigger as a redundant branch condition if the definition of `RetT::Test()` is available? Because `Test()` takes a `bool&` so it sure seems like `isSet` could be modified between the branches if the definition isn't found because it's being passed as a non-const reference to `Test()`.


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  https://reviews.llvm.org/D91037/new/

https://reviews.llvm.org/D91037



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