[llvm-branch-commits] [clang] [analyzer][NFC] Index parameter lookups by argument position (PR #221977)

[Benedek Kaibas via llvm-branch-commits]

================
@@ -577,14 +577,13 @@ ProgramStateRef CallAndMessageChecker::checkArgInitializedness(
 
   const BugType &BT = isa<ObjCMethodCall>(Call) ? MsgArgBug : CallArgBug;
 
-  const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
+  ArrayRef<ParmVarDecl *> Params = Call.parameters();
   for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) {
-    const ParmVarDecl *ParamDecl = nullptr;
-    if (FD && i < FD->getNumParams())
-      ParamDecl = FD->getParamDecl(i);
+    // For variadic functions a corresponding parameter decl might not exist.
+    const ParmVarDecl *PVD = i < Params.size() ? Params[i] : nullptr;
----------------
benedekaibas wrote:

There is no mismatch since by mapping the arguments and the parameters I make sure I index the right arguments based on the parameters. This avoids conflict when a function has both an explicit object parameter and ordinary parameters. If I would only stick to the parameters or arguments and index like that, the indexing could be wrong: if an explicit object parameter is present, it would not be counted, and then the following ordinary parameter would be at the wrong index. This is not a problem yet since explicit object parameters are not modeled, but once they are, the matching in this code is needed.

I agree that the naming and the documentation should be added/expanded. 

https://github.com/llvm/llvm-project/pull/221977