Improve docs for int_log

* Clarify rounding.
* Avoid "wrapping" wording.
* Omit wrong claim on 0 only being returned in error cases.
* Typo fix for one_less_than_next_power_of_two.

Author: Falk Hüffner

library/core/src/num/int_macros.rs

@@ -2001,7 +2001,8 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the logarithm of the number with respect to an arbitrary base.
+        /// Returns the logarithm of the number with respect to an arbitrary base,
+        /// rounded down.
         ///
         /// This method might not be optimized owing to implementation details;
         /// `log2` can produce results more efficiently for base 2, and `log10`
@@ -2010,8 +2011,8 @@ macro_rules! int_impl {
         /// # Panics
         ///
         /// When the number is zero, or if the base is not at least 2; it
-        /// panics in debug mode and the return value is wrapped to 0 in release
-        /// mode (the only situation in which the method can return 0).
+        /// panics in debug mode and the return value is 0 in release
+        /// mode.
         ///
         /// # Examples
         ///
@@ -2039,13 +2040,12 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the base 2 logarithm of the number.
+        /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
         /// When the number is zero it panics in debug mode and the return value
-        /// is wrapped to 0 in release mode (the only situation in which the
-        /// method can return 0).
+        /// is 0 in release mode.
         ///
         /// # Examples
         ///
@@ -2073,13 +2073,12 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the base 10 logarithm of the number.
+        /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
         /// When the number is zero it panics in debug mode and the return value
-        /// is wrapped to 0 in release mode (the only situation in which the
-        /// method can return 0).
+        /// is 0 in release mode.
         ///
         /// # Example
         ///
@@ -2107,7 +2106,8 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the logarithm of the number with respect to an arbitrary base.
+        /// Returns the logarithm of the number with respect to an arbitrary base,
+        /// rounded down.
         ///
         /// Returns `None` if the number is negative or zero, or if the base is not at least 2.
         ///
@@ -2147,7 +2147,7 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the base 2 logarithm of the number.
+        /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// Returns `None` if the number is negative or zero.
         ///
@@ -2171,7 +2171,7 @@ macro_rules! int_impl {
             }
         }
 
-        /// Returns the base 10 logarithm of the number.
+        /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// Returns `None` if the number is negative or zero.
         ///

library/core/src/num/uint_macros.rs

@@ -635,7 +635,8 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the logarithm of the number with respect to an arbitrary base.
+        /// Returns the logarithm of the number with respect to an arbitrary base,
+        /// rounded down.
         ///
         /// This method might not be optimized owing to implementation details;
         /// `log2` can produce results more efficiently for base 2, and `log10`
@@ -644,8 +645,7 @@ macro_rules! uint_impl {
         /// # Panics
         ///
         /// When the number is negative, zero, or if the base is not at least 2;
-        /// it panics in debug mode and the return value is wrapped to 0 in
-        /// release mode (the only situation in which the method can return 0).
+        /// it panics in debug mode and the return value is 0 in release mode.
         ///
         /// # Examples
         ///
@@ -673,13 +673,12 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the base 2 logarithm of the number.
+        /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
         /// When the number is negative or zero it panics in debug mode and
-        /// the return value is wrapped to 0 in release mode (the only situation in
-        /// which the method can return 0).
+        /// the return value is 0 in release mode.
         ///
         /// # Examples
         ///
@@ -707,13 +706,12 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the base 10 logarithm of the number.
+        /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
         /// When the number is negative or zero it panics in debug mode and the
-        /// return value is wrapped to 0 in release mode (the only situation in
-        /// which the method can return 0).
+        /// return value is 0 in release mode.
         ///
         /// # Example
         ///
@@ -741,7 +739,8 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the logarithm of the number with respect to an arbitrary base.
+        /// Returns the logarithm of the number with respect to an arbitrary base,
+        /// rounded down.
         ///
         /// Returns `None` if the number is zero, or if the base is not at least 2.
         ///
@@ -781,7 +780,7 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the base 2 logarithm of the number.
+        /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// Returns `None` if the number is zero.
         ///
@@ -805,7 +804,7 @@ macro_rules! uint_impl {
             }
         }
 
-        /// Returns the base 10 logarithm of the number.
+        /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// Returns `None` if the number is zero.
         ///
@@ -1992,7 +1991,7 @@ macro_rules! uint_impl {
         /// Returns the smallest power of two greater than or equal to `self`.
         ///
         /// When return value overflows (i.e., `self > (1 << (N-1))` for type
-        /// `uN`), it panics in debug mode and return value is wrapped to 0 in
+        /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
         /// release mode (the only situation in which method can return 0).
         ///
         /// # Examples