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Correctly handle function pointers returning a type marked nodiscard

Authored by aaron.ballman on Dec 20 2018, 12:39 PM.



When a function returns a type and that type was declared [[nodiscard]], we diagnose any unused results from that call as though the function were marked nodiscard. The same behavior should apply to calls through a function pointer.

This addresses PR31526.

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aaron.ballman created this revision.Dec 20 2018, 12:39 PM
erik.pilkington accepted this revision.Dec 20 2018, 2:12 PM



This duplicates some logic from FunctionDecl::hasUnusedResultAttr(), maybe we should move that member function to the CallExpr?


This diagnostic should also probably be improved at some point, the function wasn't declared 'nodiscard', the type was.

This revision is now accepted and ready to land.Dec 20 2018, 2:12 PM
aaron.ballman marked 3 inline comments as done.

Updated based on review feedback.

Moved FunctionDecl::hasUnusedResultAttr() and FunctionDecl::getUnusedResultAttr() to CallExpr to reduce logic duplication on checking.

aaron.ballman requested review of this revision.Dec 21 2018, 12:55 PM

There's enough churn based on the review feedback that this should probably have a second round of review just to be sure.


Good suggestion -- I think that cleans up the interface nicely.


Yeah, I noticed that as well.

erik.pilkington accepted this revision.Jan 2 2019, 12:27 PM

Still LG, sorry for the delay!

This revision is now accepted and ready to land.Jan 2 2019, 12:27 PM
aaron.ballman closed this revision.Jan 3 2019, 6:29 AM

Committed in r350317.