[alpha.webkit.UnretainedCallArgsChecker] Treat getter on a dependent smart pointer type as safe

Add the support for recognizing smart pointer type appearing as the type of the object pointer
in CXXDependentScopeMemberExpr.

Author: rniwa

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

@@ -165,6 +165,14 @@ bool tryToFindPtrOrigin(
           if (isSingleton(E->getFoundDecl()))
             return callback(E, true);
         }
+
+        if (auto *MemberExpr = dyn_cast<CXXDependentScopeMemberExpr>(CalleeE)) {
+          auto *Base = MemberExpr->getBase();
+          auto MemberName = MemberExpr->getMember().getAsString();
+          bool IsGetter = MemberName == "get" || MemberName == "ptr";
+          if (Base && isSafePtrType(Base->getType()) && IsGetter)
+            return callback(E, true);
+        }
       }
 
       // Sometimes, canonical type erroneously turns Ref<T> into T.

clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm

@@ -561,6 +561,35 @@ void foo() {
 
 } // namespace ns_retained_return_value
 
+namespace template_function {
+
+class Base {
+public:
+    virtual ~Base() = default;
+    void send(dispatch_queue_t) const;
+    void ref() const;
+    void deref() const;
+};
+
+template<typename Traits>
+class Derived : public Base {
+public:
+    virtual ~Derived() = default;
+
+    void send(typename Traits::MessageType) const;
+
+    virtual OSObjectPtr<dispatch_queue_t> msg(typename Traits::MessageType) const = 0;
+};
+
+template<typename Traits>
+void Derived<Traits>::send(typename Traits::MessageType messageType) const
+{
+    OSObjectPtr dictionary = msg(messageType);
+    Base::send(dictionary.get());
+}
+
+} // namespace template_function
+
 @interface TestObject : NSObject
 - (void)doWork:(NSString *)msg, ...;
 - (void)doWorkOnSelf;