[NFC] Cast unchecked return values to void.

[aaron.ballman]

I think the cast to void is unneeded in these cases. We typically add a cast to void when the function exists to compute a result but also has side effects. e.g., you typically call malloc() because you want the returned pointer, but if for some reason you don't want the pointer but still want the side effect of the memory allocation, you'd cast the result of the call to void. In this case, the Traverse functions exist mostly to perform side effects and the return value is only used to indicate "should we keep going?". It's reasonable to ignore the return value in this case if you don't intend to stop the traversal (and in this particular case, nothing will return false from the traversal and so there's really no need to check the return values here).

[schittir]

In D156261#4535220, @aaron.ballman wrote:

I think the cast to void is unneeded in these cases. We typically add a cast to void when the function exists to compute a result but also has side effects. e.g., you typically call malloc() because you want the returned pointer, but if for some reason you don't want the pointer but still want the side effect of the memory allocation, you'd cast the result of the call to void. In this case, the Traverse functions exist mostly to perform side effects and the return value is only used to indicate "should we keep going?". It's reasonable to ignore the return value in this case if you don't intend to stop the traversal (and in this particular case, nothing will return false from the traversal and so there's really no need to check the return values here).

I see. Thank you for the explanation. I had mixed thoughts about whether casting to void is considered a best practice in general, in addition to the use of [[nodiscard]] wherever applicable.
This seemed like a harmless change. I don't have strong opinions here, so I will go ahead and abandon these changes unless any one else disagrees.

clang/lib/Sema/SemaDeclCXX.cpp

bool TraverseCallExpr(CallExpr *E) {
       if (const auto *DR =
               dyn_cast<DeclRefExpr>(E->getCallee()->IgnoreImplicit());
           DR && DR->isImmediateEscalating()) {
         SemaRef.Diag(E->getBeginLoc(), diag::note_immediate_function_reason)
             << FD << E->getDirectCallee() << E->getDirectCallee()->isConsteval()
             << /*Call*/ 1 << /*Function*/ 0 << E->getSourceRange();
       }
       for (auto A : E->arguments()) {
-        getDerived().TraverseStmt(A);
+        (void)getDerived().TraverseStmt(A);
       }
       return true;
     }
     bool VisitDeclRefExpr(DeclRefExpr *E) {
       if (const auto *ReferencedFn = dyn_cast<FunctionDecl>(E->getDecl());
           ReferencedFn && E->isImmediateEscalating()) {
         SemaRef.Diag(E->getBeginLoc(), diag::note_immediate_function_reason)
             << FD << ReferencedFn << ReferencedFn->isConsteval()
bool TraverseDecl(Decl *D) {
       if (isa<FunctionDecl, RecordDecl>(D))
         return true;
       return Base::TraverseDecl(D);
     }
     bool TraverseType(QualType T) { return true; }
     bool VisitBlockExpr(BlockExpr *T) { return true; }
 
   } Visitor(*this, FD);
-  Visitor.TraverseStmt(FD->getBody());
+  (void)Visitor.TraverseStmt(FD->getBody());
 }
 
 /// Get the class that is directly named by the current context. This is the
 /// class for which an unqualified-id in this scope could name a constructor
 /// or destructor.
 ///
 /// If the scope specifier denotes a class, this will be that class.
 /// If the scope specifier is empty, this will be the class whose