[llvm] [XCOFF][OBJECT] get symbol size by calling XCOFF interfaces (PR #67304)

[via llvm-commits]

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@@ -822,11 +833,29 @@ class XCOFFSymbolRef {
   Expected<XCOFFCsectAuxRef> getXCOFFCsectAuxRef() const;
 
 private:
-  const XCOFFObjectFile *OwningObjectPtr;
+  const XCOFFObjectFile *getObject() const {
+    return cast<XCOFFObjectFile>(BasicSymbolRef::getObject());
+  }
+
   const XCOFFSymbolEntry32 *Entry32 = nullptr;
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diggerlin wrote:

>  I think we should let XCOFFSymbolRef derive from SymbolRef, 
if you want to XCOFFSymbolRef derive from SymbolRef ,we need to  remove the data member Entry32/Entry64 of XCOFFSymbolRef and reimplement the API of  XCOFFSymbolRef  with `SymbolPimpl` and we do not need a xcoff_symbol_iterator

https://github.com/llvm/llvm-project/pull/67304