fix invalid fixit for correctly defined function

Author: denzor200

clang-tools-extra/clang-tidy/misc/ShadowedNamespaceFunctionCheck.cpp

@@ -69,6 +69,9 @@ void ShadowedNamespaceFunctionCheck::check(
   if (!ShadowedFunc || !ShadowedNamespace)
     return;
 
+  if (ShadowedFunc->getDefinition())
+    return;
+
   // Generate warning message
   std::string NamespaceName = ShadowedNamespace->getQualifiedNameAsString();
   auto Diag = diag(Func->getLocation(), 

clang-tools-extra/test/clang-tidy/checkers/misc/shadowed-namespace-function-good.cpp

@@ -0,0 +1,9 @@
+// RUN: %check_clang_tidy %s misc-shadowed-namespace-function %t
+
+void f1();
+namespace foo {
+  void f0() {}
+  void f1() {}
+}
+void f0() {}
+void f1() {}

clang-tools-extra/test/clang-tidy/checkers/misc/shadowed-namespace-function-good2.cpp

@@ -0,0 +1,11 @@
+// RUN: %check_clang_tidy %s misc-shadowed-namespace-function %t
+
+void f1();
+namespace foo {
+  void f0();
+  void f1();
+}
+void foo::f0() {}
+void foo::f1() {}
+void f0() {}
+void f1() {}