Downgrade inefficient_to_string to pedantic

clippy_lints/src/lib.rs

@@ -1105,6 +1105,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&methods::FILTER_MAP),
         LintId::of(&methods::FILTER_MAP_NEXT),
         LintId::of(&methods::FIND_MAP),
+        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::MAP_FLATTEN),
         LintId::of(&methods::OPTION_MAP_UNWRAP_OR),
         LintId::of(&methods::OPTION_MAP_UNWRAP_OR_ELSE),
@@ -1259,7 +1260,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&methods::EXPECT_FUN_CALL),
         LintId::of(&methods::FILTER_NEXT),
         LintId::of(&methods::FLAT_MAP_IDENTITY),
-        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::INTO_ITER_ON_REF),
         LintId::of(&methods::ITERATOR_STEP_BY_ZERO),
         LintId::of(&methods::ITER_CLONED_COLLECT),
@@ -1652,7 +1652,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&loops::MANUAL_MEMCPY),
         LintId::of(&loops::NEEDLESS_COLLECT),
         LintId::of(&methods::EXPECT_FUN_CALL),
-        LintId::of(&methods::INEFFICIENT_TO_STRING),
         LintId::of(&methods::ITER_NTH),
         LintId::of(&methods::OR_FUN_CALL),
         LintId::of(&methods::SINGLE_CHAR_PATTERN),

clippy_lints/src/methods/mod.rs

@@ -698,7 +698,7 @@
     /// ["foo", "bar"].iter().map(|&s| s.to_string());
     /// ```
     pub INEFFICIENT_TO_STRING,
-    perf,
+    pedantic,
     "using `to_string` on `&&T` where `T: ToString`"
 }
 

src/lintlist/mod.rs

@@ -789,7 +789,7 @@
     },
     Lint {
         name: "inefficient_to_string",
-        group: "perf",
+        group: "pedantic",
         desc: "using `to_string` on `&&T` where `T: ToString`",
         deprecation: None,
         module: "methods",