From 9d5e9cfd97e69ddef1e25562ecd4d351e655ae17 Mon Sep 17 00:00:00 2001
From: mcarton <cartonmartin+git@gmail.com>
Date: Mon, 18 Jan 2016 19:28:06 +0100
Subject: [PATCH] Fix redundant_closure false positive

---
 src/eta_reduction.rs      | 5 +++--
 tests/compile-fail/eta.rs | 4 ++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/eta_reduction.rs b/src/eta_reduction.rs
index 46c458c6bcb6..fcc1a6893b26 100644
--- a/src/eta_reduction.rs
+++ b/src/eta_reduction.rs
@@ -45,6 +45,7 @@ fn check_closure(cx: &LateContext, expr: &Expr) {
             // || {foo(); bar()}; can't be reduced here
             return;
         }
+
         if let Some(ref ex) = blk.expr {
             if let ExprCall(ref caller, ref args) = ex.node {
                 if args.len() != decl.inputs.len() {
@@ -52,8 +53,8 @@ fn check_closure(cx: &LateContext, expr: &Expr) {
                     // is no way the closure is the same as the function
                     return;
                 }
-                if args.iter().any(|arg| is_adjusted(cx, arg)) {
-                    // Are the arguments type-adjusted? Then we need the closure
+                if is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)) {
+                    // Are the expression or the arguments type-adjusted? Then we need the closure
                     return;
                 }
                 let fn_ty = cx.tcx.expr_ty(caller);
diff --git a/tests/compile-fail/eta.rs b/tests/compile-fail/eta.rs
index a51d116d9cc8..1ffca9ac5ceb 100644
--- a/tests/compile-fail/eta.rs
+++ b/tests/compile-fail/eta.rs
@@ -21,6 +21,10 @@ fn main() {
     unsafe {
         Some(1u8).map(|a| unsafe_fn(a)); // unsafe fn
     }
+
+    // See #515
+    let a: Option<Box<::std::ops::Deref<Target = [i32]>>> =
+        Some(vec![1i32, 2]).map(|v| -> Box<::std::ops::Deref<Target = [i32]>> { Box::new(v) });
 }
 
 fn meta<F>(f: F) where F: Fn(u8) {