Auto merge of #8862 - Alexendoo:get-last-with-len, r=Jarcho,xFrednet

[rust.git] / clippy_lints / src / methods / mod.rs

diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index 8e89f43e207ccd4b46f690b3f7ea9aae1004e6b9..b820b7409304562ce75a4d7045e571eb393b2770 100644 (file)
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -45,6 +45,7 @@
 mod map_unwrap_or;
 mod needless_option_as_deref;
 mod needless_option_take;
+mod no_effect_replace;
 mod ok_expect;
 mod option_as_ref_deref;
 mod option_map_or_none;
@@ -2228,6 +2229,24 @@
     "using `.as_ref().take()` on a temporary value"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for `replace` statements which have no effect.
+    ///
+    /// ### Why is this bad?
+    /// It's either a mistake or confusing.
+    ///
+    /// ### Example
+    /// ```rust
+    /// "1234".replace("12", "12");
+    /// "1234".replacen("12", "12", 1);
+    /// ```
+    #[clippy::version = "1.62.0"]
+    pub NO_EFFECT_REPLACE,
+    suspicious,
+    "replace with no effect"
+}
+
 pub struct Methods {
     avoid_breaking_exported_api: bool,
     msrv: Option<RustcVersion>,
@@ -2328,6 +2347,7 @@ pub fn new(
     NEEDLESS_OPTION_AS_DEREF,
     IS_DIGIT_ASCII_RADIX,
     NEEDLESS_OPTION_TAKE,
+    NO_EFFECT_REPLACE,
 ]);
 
 /// Extracts a method call name, args, and `Span` of the method name.
@@ -2740,6 +2760,9 @@ fn check_methods<'tcx>(&self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
                         unnecessary_lazy_eval::check(cx, expr, recv, u_arg, "unwrap_or");
                     },
                 },
+                ("replace" | "replacen", [arg1, arg2] | [arg1, arg2, _]) => {
+                    no_effect_replace::check(cx, expr, arg1, arg2);
+                },
                 _ => {},
             }
         }