[PATCH] Fix PR19253: Do not emit global destructor warning for trivial explicitly defaulted destructors

[Stephan Tolksdorf]

  Thanks for the review!

  I previously didn't consider that hasIrrelevantDestructor is used to avoid semantic checks and hence must be false if such a check would fail for an ill-formed program. I'll upload an updated patch in a moment.


================
Comment at: lib/AST/DeclCXX.cpp:944-945
@@ -940,2 +943,4 @@
     SMKind |= SMF_Destructor;
-  else if (D->isCopyAssignmentOperator())
+    data().HasIrrelevantDestructor =
+        D->isTrivial() && D->getAccess() == AS_public && !D->isDeleted();
+  } else if (D->isCopyAssignmentOperator())
----------------
Richard Smith wrote:
> Following the pattern elsewhere in this file, this should be:
> 
>   if (D->isTrivial() && D->getAccess() == AS_public && !D->isDeleted())
>     data().HasIrrelevantDestructor = true;
> 
> I think this is also slightly more correct: in C++98, if a base class destructor is explicitly-deleted or explicitly-defaulted but non-public (we allow this as an extension), the derived class can still have a trivial, public, non-deleted destructor, that is not irrelevant (because it calls a non-irrelevant destructor, and in particular, any odr-use of the derived class destructor is ill-formed).
I think we need the negated form here:

  if (!D->isTrivial() || D->getAccess() != AS_public || D->isDeleted())
    data().HasIrrelevantDestructor = false;



http://llvm-reviews.chandlerc.com/D3190