Auto merge of #12476 - GuillaumeGomez:add-manual_arithmetic_check, r=y21

Extend `implicit_saturating_sub` lint

Fixes #10070.

It can serve as base if we want to add equivalent checks for other arithmetic operations.

Also one important note: when writing this lint, I realized that I could check for wrong conditions performed beforehand on subtraction and added another part in the lint. Considering they both rely on the same checks, I kept both in the same place. Not sure if it makes sense though...

changelog: Extend `implicit_saturating_sub` lint

CHANGELOG.md

@@ -5500,6 +5500,7 @@ Released 2018-09-13
 [`invalid_regex`]: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_regex
 [`invalid_upcast_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_upcast_comparisons
 [`invalid_utf8_in_unchecked`]: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_utf8_in_unchecked
+[`inverted_saturating_sub`]: https://rust-lang.github.io/rust-clippy/master/index.html#inverted_saturating_sub
 [`invisible_characters`]: https://rust-lang.github.io/rust-clippy/master/index.html#invisible_characters
 [`is_digit_ascii_radix`]: https://rust-lang.github.io/rust-clippy/master/index.html#is_digit_ascii_radix
 [`items_after_statements`]: https://rust-lang.github.io/rust-clippy/master/index.html#items_after_statements

clippy_config/src/msrvs.rs

@@ -36,7 +36,7 @@ msrv_aliases! {
     1,52,0 { STR_SPLIT_ONCE, REM_EUCLID_CONST }
     1,51,0 { BORROW_AS_PTR, SEEK_FROM_CURRENT, UNSIGNED_ABS }
     1,50,0 { BOOL_THEN, CLAMP }
-    1,47,0 { TAU, IS_ASCII_DIGIT_CONST, ARRAY_IMPL_ANY_LEN }
+    1,47,0 { TAU, IS_ASCII_DIGIT_CONST, ARRAY_IMPL_ANY_LEN, SATURATING_SUB_CONST }
     1,46,0 { CONST_IF_MATCH }
     1,45,0 { STR_STRIP_PREFIX }
     1,43,0 { LOG2_10, LOG10_2, NUMERIC_ASSOCIATED_CONSTANTS }

clippy_lints/src/declared_lints.rs

@@ -217,6 +217,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::implicit_return::IMPLICIT_RETURN_INFO,
     crate::implicit_saturating_add::IMPLICIT_SATURATING_ADD_INFO,
     crate::implicit_saturating_sub::IMPLICIT_SATURATING_SUB_INFO,
+    crate::implicit_saturating_sub::INVERTED_SATURATING_SUB_INFO,
     crate::implied_bounds_in_impls::IMPLIED_BOUNDS_IN_IMPLS_INFO,
     crate::incompatible_msrv::INCOMPATIBLE_MSRV_INFO,
     crate::inconsistent_struct_constructor::INCONSISTENT_STRUCT_CONSTRUCTOR_INFO,