[clang] [analyzer] Use dynamic type when invalidating by a member function call (PR #111138)

[Gábor Horváth via cfe-commits]

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@@ -797,6 +798,10 @@ RuntimeDefinition CXXInstanceCall::getRuntimeDefinition() const {
     return {};
   }
 
+  const MemRegion *R = getCXXThisVal().getAsRegion();
+  DynamicTypeInfo DynType = getDynamicTypeInfo(getState(), R);
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Xazax-hun wrote:

My understanding is that we do this lookup twice now and we only need the result of `DynType.canBeASubClass()`.

I wonder if it would make sense for ` getDeclForDynamicType()` to return a pair, the pointer to a declaration and a bool if the dynamic type could be a subclass to avoid the extra lookup. Other clients of that API might also want to know how precise is the dynamic type. 

https://github.com/llvm/llvm-project/pull/111138