Experiment: lint all .is_multiple_of() candidates

This is not meant to be merged as-is. Also, tests have been spared to
avoid modifying the 8 tests that use lintable expressions; they still
use 4 as a value.

Author: samueltardieu

book/src/lint_configuration.md

@@ -706,7 +706,7 @@ The maximum number of bounds a trait can have to be linted
 ## `min-divisor`
 The smallest divisor to propose `.is_multiple_of()` for.
 
-**Default Value:** `4`
+**Default Value:** `0`
 
 ---
 **Affected lints:**

clippy_config/src/conf.rs

@@ -585,7 +585,7 @@ define_Conf! {
     max_trait_bounds: u64 = 3,
     /// The smallest divisor to propose `.is_multiple_of()` for.
     #[lints(manual_is_multiple_of)]
-    min_divisor: u64 = 4,
+    min_divisor: u64 = 0,
     /// Minimum chars an ident can have, anything below or equal to this will be linted.
     #[lints(min_ident_chars)]
     min_ident_chars_threshold: u64 = 1,

clippy_lints/src/casts/cast_sign_loss.rs

@@ -167,7 +167,7 @@ fn pow_call_result_sign(cx: &LateContext<'_>, base: &Expr<'_>, exponent: &Expr<'
 
     // Rust's integer pow() functions take an unsigned exponent.
     let exponent_val = get_const_unsigned_int_eval(cx, exponent, None);
-    let exponent_is_even = exponent_val.map(|val| val % 2 == 0);
+    let exponent_is_even = exponent_val.map(|val| val.is_multiple_of(2));
 
     match (base_sign, exponent_is_even) {
         // Non-negative bases always return non-negative results, ignoring overflow.

clippy_lints/src/lib.rs

@@ -12,6 +12,7 @@
 #![feature(round_char_boundary)]
 #![feature(rustc_private)]
 #![feature(stmt_expr_attributes)]
+#![feature(unsigned_is_multiple_of)]
 #![feature(unwrap_infallible)]
 #![recursion_limit = "512"]
 #![allow(

tests/clippy.toml

@@ -1 +1,2 @@
 # default config for tests, overrides clippy.toml at the project root
+min-divisor = 4