loplugin:unnecessaryoverride: no warnings when fns are actually different

Change-Id: I90d8af7a1affa459400b1cae4805e3a80b6c5200
Reviewed-on: https://gerrit.libreoffice.org/44593
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/test/unnecessaryoverride.cxx

@@ -11,6 +11,10 @@ struct Base
 {
     virtual ~Base();
     virtual void f();
+    void variadic(int, ...);
+    void cv() const volatile;
+    void ref();
+    static void staticFn();
 };
 
 struct SimpleDerived : Base
@@ -45,4 +49,12 @@ struct MultiClassDerived : Intermediate1, MultiClassIntermediate2
     void f() override { Intermediate1::f(); } // no warning
 };
 
+struct DerivedDifferent : Base
+{
+    void variadic(int x) { Base::variadic(x); } // no warning
+    void cv() { Base::cv(); } // no warning
+    void ref() && { Base::ref(); } // no warning
+    void staticFn() { Base::staticFn(); } // no warning
+};
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */

compilerplugins/clang/unnecessaryoverride.cxx

@@ -399,6 +399,15 @@ const CXXMethodDecl* UnnecessaryOverride::findOverriddenOrSimilarMethodInSupercl
             if (!baseMethod->getDeclName().isIdentifier() || methodDecl->getName() != baseMethod->getName()) {
                 continue;
             }
+            if (methodDecl->isStatic() != baseMethod->isStatic()
+                || methodDecl->isConst() != baseMethod->isConst()
+                || methodDecl->isVolatile() != baseMethod->isVolatile()
+                || (methodDecl->getRefQualifier()
+                    != baseMethod->getRefQualifier())
+                || methodDecl->isVariadic() != baseMethod->isVariadic())
+            {
+                continue;
+            }
             if (compat::getReturnType(*methodDecl).getCanonicalType()
                 != compat::getReturnType(*baseMethod).getCanonicalType())
             {