Auto merge of #7671 - dtolnay-contrib:singlecharnames, r=xFrednet

Downgrade many_single_char_names to pedantic

As suggested by `@flip1995` in #7666 (comment), by today's standards this lint would be considered `pedantic`.

This is one of the most widely suppressed Clippy lints on crates.io according to https://github.com/dtolnay/noisy-clippy.

In my opinion this lint is just too domain specific for Clippy to have reliable visibility into. Sure there are some cases where the author is just being lazy and could use a kick in the butt, but we're still left with an enormous number of suppressions where single chars are the most appropriate name. For example in the context of colors, a function using `h`, `s`, `l`, `r`, `g`, `b` is 100% sensible and spelling all those out is silly, but it's past the default lint threshold.

---

changelog: Moved [`many_single_char_names`] to `pedantic`

Author: bors

clippy_lints/src/lib.rs

@@ -1137,6 +1137,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(needless_continue::NEEDLESS_CONTINUE),
         LintId::of(needless_for_each::NEEDLESS_FOR_EACH),
         LintId::of(needless_pass_by_value::NEEDLESS_PASS_BY_VALUE),
+        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(non_expressive_names::SIMILAR_NAMES),
         LintId::of(pass_by_ref_or_value::LARGE_TYPES_PASSED_BY_VALUE),
         LintId::of(pass_by_ref_or_value::TRIVIALLY_COPY_PASS_BY_REF),
@@ -1393,7 +1394,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(non_copy_const::BORROW_INTERIOR_MUTABLE_CONST),
         LintId::of(non_copy_const::DECLARE_INTERIOR_MUTABLE_CONST),
         LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
-        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(non_octal_unix_permissions::NON_OCTAL_UNIX_PERMISSIONS),
         LintId::of(open_options::NONSENSICAL_OPEN_OPTIONS),
         LintId::of(option_env_unwrap::OPTION_ENV_UNWRAP),
@@ -1567,7 +1567,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(non_copy_const::BORROW_INTERIOR_MUTABLE_CONST),
         LintId::of(non_copy_const::DECLARE_INTERIOR_MUTABLE_CONST),
         LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
-        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(ptr::CMP_NULL),
         LintId::of(ptr::PTR_ARG),
         LintId::of(ptr_eq::PTR_EQ),

clippy_lints/src/non_expressive_names.rs

@@ -43,7 +43,7 @@ declare_clippy_lint! {
     /// let (a, b, c, d, e, f, g) = (...);
     /// ```
     pub MANY_SINGLE_CHAR_NAMES,
-    style,
+    pedantic,
     "too many single character bindings"
 }
 

clippy_utils/src/hir_utils.rs

@@ -540,7 +540,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         std::mem::discriminant(&b.rules).hash(&mut self.s);
     }
 
-    #[allow(clippy::many_single_char_names, clippy::too_many_lines)]
+    #[allow(clippy::too_many_lines)]
     pub fn hash_expr(&mut self, e: &Expr<'_>) {
         let simple_const = self
             .maybe_typeck_results

tests/ui-toml/toml_trivially_copy/test.rs

@@ -2,7 +2,6 @@
 // normalize-stderr-test "\(limit: \d+ byte\)" -> "(limit: N byte)"
 
 #![deny(clippy::trivially_copy_pass_by_ref)]
-#![allow(clippy::many_single_char_names)]
 
 #[derive(Copy, Clone)]
 struct Foo(u8);

tests/ui-toml/toml_trivially_copy/test.stderr

@@ -1,5 +1,5 @@
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/test.rs:15:11
+  --> $DIR/test.rs:14:11
    |
 LL | fn bad(x: &u16, y: &Foo) {}
    |           ^^^^ help: consider passing by value instead: `u16`
@@ -11,7 +11,7 @@ LL | #![deny(clippy::trivially_copy_pass_by_ref)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/test.rs:15:20
+  --> $DIR/test.rs:14:20
    |
 LL | fn bad(x: &u16, y: &Foo) {}
    |                    ^^^^ help: consider passing by value instead: `Foo`

tests/ui/deref_addrof.fixed

@@ -9,7 +9,7 @@ fn get_reference(n: &usize) -> &usize {
     n
 }
 
-#[allow(clippy::many_single_char_names, clippy::double_parens)]
+#[allow(clippy::double_parens)]
 #[allow(unused_variables, unused_parens)]
 fn main() {
     let a = 10;

tests/ui/deref_addrof.rs

@@ -9,7 +9,7 @@ fn get_reference(n: &usize) -> &usize {
     n
 }
 
-#[allow(clippy::many_single_char_names, clippy::double_parens)]
+#[allow(clippy::double_parens)]
 #[allow(unused_variables, unused_parens)]
 fn main() {
     let a = 10;

tests/ui/eq_op.rs

@@ -2,7 +2,7 @@
 
 #[rustfmt::skip]
 #[warn(clippy::eq_op)]
-#[allow(clippy::identity_op, clippy::double_parens, clippy::many_single_char_names)]
+#[allow(clippy::identity_op, clippy::double_parens)]
 #[allow(clippy::no_effect, unused_variables, clippy::unnecessary_operation, clippy::short_circuit_statement)]
 #[allow(clippy::nonminimal_bool)]
 #[allow(unused)]

tests/ui/eta.fixed

@@ -4,7 +4,6 @@
     unused,
     clippy::no_effect,
     clippy::redundant_closure_call,
-    clippy::many_single_char_names,
     clippy::needless_pass_by_value,
     clippy::option_map_unit_fn
 )]

tests/ui/eta.rs

@@ -4,7 +4,6 @@
     unused,
     clippy::no_effect,
     clippy::redundant_closure_call,
-    clippy::many_single_char_names,
     clippy::needless_pass_by_value,
     clippy::option_map_unit_fn
 )]