From b831bd1d1d16c2733b2c26196163f68c74f3c271 Mon Sep 17 00:00:00 2001
From: Georg Brandl <georg@python.org>
Date: Wed, 12 Aug 2015 10:53:14 +0200
Subject: [PATCH] len_zero: display full suggested expr in message

---
 src/len_zero.rs                | 14 +++++++-------
 tests/compile-fail/len_zero.rs |  6 ++++++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/len_zero.rs b/src/len_zero.rs
index dea713180..298522ed2 100644
--- a/src/len_zero.rs
+++ b/src/len_zero.rs
@@ -9,7 +9,7 @@ use rustc::middle::ty::{self, TypeVariants, TypeAndMut, MethodTraitItemId, ImplO
 use rustc::middle::def::{DefTy, DefStruct, DefTrait};
 use syntax::codemap::{Span, Spanned};
 use syntax::ast::*;
-use utils::{span_lint, walk_ptrs_ty};
+use utils::{span_lint, walk_ptrs_ty, snippet};
 
 declare_lint!(pub LEN_ZERO, Warn,
               "Warn when .is_empty() could be used instead of checking .len()");
@@ -92,24 +92,24 @@ fn is_self_sig(sig: &MethodSig) -> bool {
         false } else { sig.decl.inputs.len() == 1 }
 }
 
-fn check_cmp(cx: &Context, span: Span, left: &Expr, right: &Expr, empty: &str) {
+fn check_cmp(cx: &Context, span: Span, left: &Expr, right: &Expr, op: &str) {
     match (&left.node, &right.node) {
         (&ExprLit(ref lit), &ExprMethodCall(ref method, _, ref args)) =>
-            check_len_zero(cx, span, method, args, lit, empty),
+            check_len_zero(cx, span, method, args, lit, op),
         (&ExprMethodCall(ref method, _, ref args), &ExprLit(ref lit)) =>
-            check_len_zero(cx, span, method, args, lit, empty),
+            check_len_zero(cx, span, method, args, lit, op),
         _ => ()
     }
 }
 
 fn check_len_zero(cx: &Context, span: Span, method: &SpannedIdent,
-                  args: &[P<Expr>], lit: &Lit, empty: &str) {
+                  args: &[P<Expr>], lit: &Lit, op: &str) {
     if let &Spanned{node: LitInt(0, _), ..} = lit {
         if method.node.name == "len" && args.len() == 1 &&
             has_is_empty(cx, &*args[0]) {
                 span_lint(cx, LEN_ZERO, span, &format!(
-                    "consider replacing the len comparison with `{}_.is_empty()`",
-                    empty))
+                    "consider replacing the len comparison with `{}{}.is_empty()`",
+                    op, snippet(cx, args[0].span, "_")))
             }
     }
 }
diff --git a/tests/compile-fail/len_zero.rs b/tests/compile-fail/len_zero.rs
index 3785a518e..626e5557f 100755
--- a/tests/compile-fail/len_zero.rs
+++ b/tests/compile-fail/len_zero.rs
@@ -87,6 +87,12 @@ fn main() {
     if hie.len() == 0 { //~ERROR consider replacing the len comparison
         println!("Or this!");
     }
+    if hie.len() != 0 { //~ERROR consider replacing the len comparison
+        println!("Or this!");
+    }
+    if hie.len() > 0 { //~ERROR consider replacing the len comparison
+        println!("Or this!");
+    }
     assert!(!hie.is_empty());
 
     let wie : &WithIsEmpty = &Wither;