Fix a bug in abs_diff

tgross35 · tgross35 · commit e9782cecbb8b · 2024-12-22T22:24:38.000Z
These were taken from `compiler-builtins` but the implementation has a bug near the integer limits. Fixed in `compiler-builtins` by using `core`'s implementation at [1], this is the corresponding fix for `libm`. [1]: rust-lang/compiler-builtins#736
diff --git a/src/math/support/int_traits.rs b/src/math/support/int_traits.rs
@@ -184,7 +184,7 @@ macro_rules! int_impl {
             }
 
             fn abs_diff(self, other: Self) -> Self {
-                if self < other { other.wrapping_sub(self) } else { self.wrapping_sub(other) }
+                self.abs_diff(other)
             }
 
             int_impl_common!($uty);
@@ -221,7 +221,7 @@ macro_rules! int_impl {
             }
 
             fn abs_diff(self, other: Self) -> $uty {
-                self.wrapping_sub(other).wrapping_abs() as $uty
+                self.abs_diff(other)
             }
 
             int_impl_common!($ity);

Original file line number	Diff line number	Diff line change
`@@ -184,7 +184,7 @@ macro_rules! int_impl {`
`184`	`184`	`}`
`185`	`185`
`186`	`186`	`fn abs_diff(self, other: Self) -> Self {`
`187`		`- if self < other { other.wrapping_sub(self) } else { self.wrapping_sub(other) }`
	`187`	`+ self.abs_diff(other)`
`188`	`188`	`}`
`189`	`189`
`190`	`190`	`int_impl_common!($uty);`
`@@ -221,7 +221,7 @@ macro_rules! int_impl {`
`221`	`221`	`}`
`222`	`222`
`223`	`223`	`fn abs_diff(self, other: Self) -> $uty {`
`224`		`- self.wrapping_sub(other).wrapping_abs() as $uty`
	`224`	`+ self.abs_diff(other)`
`225`	`225`	`}`
`226`	`226`
`227`	`227`	`int_impl_common!($ity);`