Touch up checked_log PR

Author: dtolnay

src/libcore/num/mod.rs

@@ -2163,7 +2163,7 @@ assert_eq!((-a).rem_euclid(-b), 1);
         doc_comment! {
             concat!("Returns the logarithm of the number with respect to an arbitrary base.
 
-Returns `None` if the number is zero, or if the base is zero or one.
+Returns `None` if the number is negative or zero, or if the base is not at least 2.
 
 This method may not be optimized owing to implementation details;
 `self.checked_log2()` can produce results more efficiently for base 2, and
@@ -2214,7 +2214,7 @@ assert_eq!(result, Some(1));
         doc_comment! {
             concat!("Returns the base 2 logarithm of the number.
 
-Returns `None` if the number is lower than 1.
+Returns `None` if the number is negative or zero.
 
 # Examples
 
@@ -2246,7 +2246,7 @@ assert_eq!(result, Some(1));
         doc_comment! {
             concat!("Returns the base 10 logarithm of the number.
 
-Returns `None` if the number is lower than 1.
+Returns `None` if the number is negative or zero.
 
 # Examples
 
@@ -2269,8 +2269,6 @@ assert_eq!(result, Some(1));
             }
         }
 
-
-
         doc_comment! {
             concat!("Computes the absolute value of `self`.
 
@@ -4283,7 +4281,7 @@ assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer
         doc_comment! {
             concat!("Returns the logarithm of the number with respect to an arbitrary base.
 
-Returns `None` if the number is negative or zero, or if the base is negative, zero, or one.
+Returns `None` if the number is zero, or if the base is not at least 2.
 
 This method may not be optimized owing to implementation details;
 `self.checked_log2()` can produce results more efficiently for base 2, and
@@ -4334,7 +4332,7 @@ assert_eq!(result, Some(1));
         doc_comment! {
             concat!("Returns the base 2 logarithm of the number.
 
-Returns `None` if the number is lower than 1.
+Returns `None` if the number is zero.
 
 # Examples
 
@@ -4366,7 +4364,7 @@ assert_eq!(result, Some(1));
         doc_comment! {
             concat!("Returns the base 10 logarithm of the number.
 
-Returns `None` if the number is lower than 1.
+Returns `None` if the number is zero.
 
 # Examples
 

src/libcore/tests/num/int_log.rs

@@ -16,12 +16,13 @@ fn checked_log() {
         assert_eq!(i.checked_log(4), None);
     }
     for i in 1..=i16::MAX {
-        assert_eq!(i.checked_log(13), Some((i as f32).checked_log(13.0) as i16));
+        assert_eq!(i.checked_log(13), Some((i as f32).log(13.0) as i16));
     }
     for i in 1..=u16::MAX {
-        assert_eq!(i.checked_log(13), Some((i as f32).checked_log(13.0) as u16));
+        assert_eq!(i.checked_log(13), Some((i as f32).log(13.0) as u16));
     }
 }
+
 #[test]
 fn checked_log2() {
     assert_eq!(5u32.checked_log2(), Some(2));
@@ -30,35 +31,34 @@ fn checked_log2() {
     assert_eq!((-55i16).checked_log2(), None);
 
     for i in 1..=u8::MAX {
-        assert_eq!(i.checked_log2(), Some((i as f32).checked_log2() as u8));
+        assert_eq!(i.checked_log2(), Some((i as f32).log2() as u8));
     }
     for i in 1..=u16::MAX {
-        assert_eq!(i.checked_log2(), Some((i as f32).checked_log2() as u16));
+        assert_eq!(i.checked_log2(), Some((i as f32).log2() as u16));
     }
     for i in i8::MIN..=0 {
         assert_eq!(i.checked_log2(), None);
     }
     for i in 1..=i8::MAX {
-        assert_eq!(i.checked_log2(), Some((i as f32).checked_log2() as i8));
+        assert_eq!(i.checked_log2(), Some((i as f32).log2() as i8));
     }
     for i in i16::MIN..=0 {
         assert_eq!(i.checked_log2(), None);
     }
     for i in 1..=i16::MAX {
-        assert_eq!(i.checked_log2(), Some((i as f32).checked_log2() as i16));
+        assert_eq!(i.checked_log2(), Some((i as f32).log2() as i16));
     }
 }
 
 #[test]
 fn checked_log10() {
-    // checked_log10()
     for i in i16::MIN..=0 {
         assert_eq!(i.checked_log10(), None);
     }
     for i in 1..=i16::MAX {
-        assert_eq!(i.checked_log10(), Some((i as f32).checked_log10() as i16));
+        assert_eq!(i.checked_log10(), Some((i as f32).log10() as i16));
     }
     for i in 1..=u16::MAX {
-        assert_eq!(i.checked_log10(), Some((i as f32).checked_log10() as u16));
+        assert_eq!(i.checked_log10(), Some((i as f32).log10() as u16));
     }
 }