Fix cast_sign_loss false positive for float to uint casts

The cast_sign_loss lint was incorrectly triggering on float to unsigned integer casts, which cannot actually lose sign information since floats don't have the same sign semantics as signed integers. This change modifies the should_lint function to exclude float to uint casts from the cast_sign_loss lint. changelog: Fix [] false positive for float to unsigned integer casts fixed tests

Author: krikera

clippy_lints/src/casts/cast_sign_loss.rs

@@ -76,9 +76,8 @@ fn should_lint<'cx>(cx: &LateContext<'cx>, cast_op: &Expr<'_>, cast_from: Ty<'cx
  true
  },
 
- (false, true) => !cast_to.is_signed(),
-
- (_, _) => false,
+ // Don't lint float -> int casts as they have different semantics
+ _ => false,
  }
 }
 

tests/ui/cast.rs

@@ -47,7 +47,6 @@ fn main() {
 
  1f32 as u32;
  //~^ cast_possible_truncation
- //~| cast_sign_loss
 
  1f64 as f32;
  //~^ cast_possible_truncation
@@ -63,12 +62,10 @@ fn main() {
 
  1f64 as usize;
  //~^ cast_possible_truncation
- //~| cast_sign_loss
 
  1f32 as u32 as u16;
  //~^ cast_possible_truncation
  //~| cast_possible_truncation
- //~| cast_sign_loss
 
  {
  let _x: i8 = 1i32 as _;
@@ -82,7 +79,6 @@ fn main() {
 
  1f32 as u8;
  //~^ cast_possible_truncation
- //~| cast_sign_loss
  }
  // Test clippy::cast_possible_wrap
  1u8 as i8;