Currently, handleCall takes a CallExpr as an argument and retrieves the arguments from there. This changes it to take the argument list as a separate argument of type ArrayRef.
The main motivation that I want VisitCXXConstructExpr to also be able to invoke handleCall, even though CXXConstructExpr is not a subclass of CallExpr. But actually adding that will wait for a future patch.
However, this also fixes a minor bug in VisitCXXOperatorCallExpr:
if (const auto *MCall = dyn_cast<CXXMemberCallExpr>(Call)) handleCall(MCall, MCall->getImplicitObjectArgument(), FunDecl); else handleCall(Call, Call->getArg(0), FunDecl);
Call here is a CXXOperatorCallExpr, and CXXMemberCallExpr is a sibling class, so the cast will never succeed. CXXMemberCallExprs go through a separate visitor, VisitCXXMemberCallExpr.
On the other hand, this logic may be intended to reflect the fact that C++ operators can be declared as either methods or free functions. The correct way to differentiate these is shown at the beginning of handleCall:
unsigned Offset = 0; if (isa<CXXOperatorCallExpr>(Call) && isa<CXXMethodDecl>(FunD)) Offset = 1; // first argument is 'this'
For CXXOperatorCallExprs, if the decl is a CXXMethodDecl, the first argument is this; otherwise there is no this.
Going back to the other first: currently, since the dyn_cast always fails, it always passes Call->getArg(0) as ObjArg (i.e. the expression representing this), even for operators declared as free functions. However, this is harmless, because ObjArg is only used if the function is marked as one of set_typestate or test_typestate, or callable_when, yet those attributes are only allowed on methods. Call->getArg(0) will crash if there are zero arguments, but the only kind of non-method operator function allowed to have zero arguments is a user-defined literal, and those do not produce CXXOperatorCallExprs.
The bug could be fixed by changing the first snippet to check for CXXMethodDecl like the second one, but this refactor makes things cleaner by only having to check in one place.