Auto merge of #10470 - Manishearth:kill-str-string, r=KiChjang

Remove str_to_string lint

Specialization makes all of the options equally efficient.

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1 files changed, 0 insertions, 48 deletions

diff --git a/components/plugins/lints/str_to_string.rs b/components/plugins/lints/str_to_string.rs
deleted file mode 100644
index 8a1f1530898..00000000000
--- a/components/plugins/lints/str_to_string.rs
+++ /dev/null
@@ -1,48 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-use rustc::lint::{LateContext, LintPass, LintArray, LateLintPass, LintContext};
-use rustc::ty;
-use rustc_front::hir;
-
-declare_lint!(STR_TO_STRING, Deny,
-              "Warn when a String could use to_owned() instead of to_string()");
-
-/// Prefer str.to_owned() over str.to_string()
-///
-/// The latter creates a `Formatter` and is 5x slower than the former
-pub struct StrToStringPass;
-
-impl LintPass for StrToStringPass {
-    fn get_lints(&self) -> LintArray {
-        lint_array!(STR_TO_STRING)
-    }
-}
-
-impl LateLintPass for StrToStringPass {
-    fn check_expr(&mut self, cx: &LateContext, expr: &hir::Expr) {
-        match expr.node {
-            hir::ExprMethodCall(ref method, _, ref args)
-                if method.node.as_str() == "to_string"
-                && is_str(cx, &*args[0]) => {
-                cx.span_lint(STR_TO_STRING, expr.span,
-                             "str.to_owned() is more efficient than str.to_string(), please use it instead");
-            },
-            _ => ()
-        }
-
-        fn is_str(cx: &LateContext, expr: &hir::Expr) -> bool {
-            fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
-                match ty.sty {
-                    ty::TyRef(_, ref tm) | ty::TyRawPtr(ref tm) => walk_ty(tm.ty),
-                    _ => ty
-                }
-            }
-            match walk_ty(cx.tcx.expr_ty(expr)).sty {
-                ty::TyStr => true,
-                _ => false
-            }
-        }
-    }
-}