Index: clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
+++ clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
@@ -37,7 +37,7 @@
                       functionDecl(unless(anyOf(
                           isDefinition(), isDefaulted(),
                           doesDeclarationForceExternallyVisibleDefinition(),
-                          hasParent(friendDecl()))))))
+                          hasAncestor(friendDecl()))))))
           .bind("Decl"),
       this);
 }
Index: clang-tools-extra/test/clang-tidy/checkers/readability-redundant-declaration.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/readability-redundant-declaration.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/readability-redundant-declaration.cpp
@@ -66,8 +66,14 @@
 struct Friendly {
   friend void best_friend();
   friend void enemy();
+
+  template <typename T>
+  friend void generic_friend();
 };
 
+template <typename T>
+void generic_friend() {}
+
 void enemy();
 
 namespace macros {