From aa9cf07d56fac7044e6890d66759ab9903d352ef Mon Sep 17 00:00:00 2001
From: Grzegorz <grzegorz.bartoszek@thaumatec.com>
Date: Sun, 31 Mar 2019 14:10:17 +0200
Subject: [PATCH] redundant closure for functions restricted to FnDefs

---
 clippy_lints/src/eta_reduction.rs | 3 +++
 tests/ui/eta.fixed                | 5 +++++
 tests/ui/eta.rs                   | 5 +++++
 3 files changed, 13 insertions(+)

diff --git a/clippy_lints/src/eta_reduction.rs b/clippy_lints/src/eta_reduction.rs
index 63abe47b4428..cb17ef18429a 100644
--- a/clippy_lints/src/eta_reduction.rs
+++ b/clippy_lints/src/eta_reduction.rs
@@ -65,6 +65,9 @@ fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr) {
             if !(is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)));
 
             let fn_ty = cx.tables.expr_ty(caller);
+
+            if let ty::FnDef(_, _) = fn_ty.sty;
+
             if !type_is_unsafe_function(cx, fn_ty);
 
             if compare_inputs(&mut iter_input_pats(decl, body), &mut args.into_iter());
diff --git a/tests/ui/eta.fixed b/tests/ui/eta.fixed
index 7e487fe21679..6f9457a4a29d 100644
--- a/tests/ui/eta.fixed
+++ b/tests/ui/eta.fixed
@@ -133,3 +133,8 @@ fn divergent(_: u8) -> ! {
 fn generic<T>(_: T) -> u8 {
     0
 }
+
+fn passes_fn_mut(mut x: Box<dyn FnMut()>) {
+    requires_fn_once(|| x());
+}
+fn requires_fn_once<T: FnOnce()>(_: T) {}
diff --git a/tests/ui/eta.rs b/tests/ui/eta.rs
index a0d83c438251..11f142e17dfb 100644
--- a/tests/ui/eta.rs
+++ b/tests/ui/eta.rs
@@ -133,3 +133,8 @@ fn divergent(_: u8) -> ! {
 fn generic<T>(_: T) -> u8 {
     0
 }
+
+fn passes_fn_mut(mut x: Box<dyn FnMut()>) {
+    requires_fn_once(|| x());
+}
+fn requires_fn_once<T: FnOnce()>(_: T) {}