[clang] [ObjC] Expand isClassLayoutKnownStatically to base classes as long as the implementation of it is known (PR #85465)

[via cfe-commits]

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@@ -1592,6 +1592,11 @@ class CGObjCNonFragileABIMac : public CGObjCCommonMac {
   bool isClassLayoutKnownStatically(const ObjCInterfaceDecl *ID) {
     // Test a class by checking its superclasses up to
     // its base class if it has one.
+
+    // Cannot check a null class
+    if (!ID)
+      return false;
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AZero13 wrote:

This shouldn't happen but if it does, return false like we used to do because otherwise we will crash as this is dereferencing a null pointer

https://github.com/llvm/llvm-project/pull/85465