[clang-tidy] readability-redundant-declaration false positive for defaulted function

[fgross]

Summary

template <class T>
struct C {
  C();
};

template <class T>
C<T>::C() = default;

Causes a readability-redundant-declaration diagnostic. This is caused by isDefinition not matching defaulted functions.

[alexfh]

LG. Thank you!

clang-tidy/readability/RedundantDeclarationCheck.cpp

 
 using namespace clang::ast_matchers;
 
 namespace clang {
 namespace tidy {
 namespace readability {
 
 void RedundantDeclarationCheck::registerMatchers(MatchFinder *Finder) {
-  auto UnlessDefinition = unless(isDefinition());
-  Finder->addMatcher(namedDecl(anyOf(varDecl(UnlessDefinition),
-                                     functionDecl(UnlessDefinition)))
-                         .bind("Decl"),
-                     this);
+  Finder->addMatcher(
+      namedDecl(
+          anyOf(varDecl(unless(isDefinition())),
+                functionDecl(unless(anyOf(isDefinition(), isDefaulted())))))
 }
 
 void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
   const auto *D = Result.Nodes.getNodeAs<NamedDecl>("Decl");
   const auto *Prev = D->getPreviousDecl();
   if (!Prev)
     return;
   if (!Prev->getLocation().isValid())

test/clang-tidy/readability-redundant-declaration.cpp

 void *operator new(std::size_t) __attribute__((__externally_visible__));
 void *operator new[](std::size_t) __attribute__((__externally_visible__));
 
 // Don't warn about static member definition.
 struct C {
   static int I;
 };
 int C::I;
+
+template <class T>
+struct C2 {
+  C2();
+};
+
+template <class T>
+C2<T>::C2() = default;