Merge pull request #559 from mcarton/redundant_closure

Fix redundant_closure false positive

Author: llogiq

src/eta_reduction.rs

@@ -45,15 +45,16 @@ 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() {
                     // Not the same number of arguments, there
                     // 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);

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) {