[alpha.webkit.UncheckedCallArgsChecker] Forwarding r-value reference should not result in a warning

This PR fixes the bug that the checker emits a warning when a function takes T&& and passes it to
another function using std::move. We should treat std::move like any other pointer conversion and
the origin of the pointer to be that of the argument.

Author: rniwa

clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp

@@ -118,6 +118,11 @@ bool tryToFindPtrOrigin(
           }
         }
       }
+      
+      if (call->isCallToStdMove() && call->getNumArgs() == 1) {
+        E = call->getArg(0)->IgnoreParenCasts();
+        continue;
+      }
 
       if (auto *callee = call->getDirectCallee()) {
         if (isCtorOfSafePtr(callee)) {

clang/test/Analysis/Checkers/WebKit/call-args-checked.cpp

@@ -2,6 +2,20 @@
 
 #include "mock-types.h"
 
+namespace std {
+
+template <typename T> struct remove_reference {
+  typedef T type;
+};
+
+template <typename T> struct remove_reference<T&> {
+  typedef T type;
+};
+
+template<typename T> typename remove_reference<T>::type&& move(T&& t);
+
+} // namespace std
+
 RefCountableAndCheckable* makeObj();
 CheckedRef<RefCountableAndCheckable> makeObjChecked();
 void someFunction(RefCountableAndCheckable*);
@@ -54,3 +68,12 @@ void foo() {
 }
 
 }
+
+namespace call_with_std_move {
+
+void consume(CheckedObj&&);
+void foo(CheckedObj&& obj) {
+  consume(std::move(obj));
+}
+
+}