[alpha.webkit.NoUnretainedMemberChecker] Ignore system-header-defined ivar / property of a forward declared type (#133755)

Prior to this PR, we were emitting warnings for Objective-C ivars and
properties if the forward declaration of the type appeared first in a
non-system header. This PR fixes the checker so tha we'd ignore ivars
and properties defined for a forward declared type.

Author: rniwa

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

@@ -133,6 +133,8 @@ class RawPtrRefMemberChecker
 
   void visitIvarDecl(const ObjCContainerDecl *CD,
                      const ObjCIvarDecl *Ivar) const {
+    if (BR->getSourceManager().isInSystemHeader(Ivar->getLocation()))
+      return;
     auto QT = Ivar->getType();
     const Type *IvarType = QT.getTypePtrOrNull();
     if (!IvarType)
@@ -154,6 +156,8 @@ class RawPtrRefMemberChecker
 
   void visitObjCPropertyDecl(const ObjCContainerDecl *CD,
                              const ObjCPropertyDecl *PD) const {
+    if (BR->getSourceManager().isInSystemHeader(PD->getLocation()))
+      return;
     auto QT = PD->getType();
     const Type *PropType = QT.getTypePtrOrNull();
     if (!PropType)

clang/test/Analysis/Checkers/WebKit/unretained-members.mm

@@ -1,5 +1,7 @@
 // RUN: %clang_analyze_cc1 -analyzer-checker=alpha.webkit.NoUnretainedMemberChecker -verify %s
 
+@class SystemObject;
+
 #include "objc-mock-types.h"
 #include "mock-system-header.h"