docs: do not call integer overflows as underflows

src/libcore/num/bignum.rs

@@ -114,7 +114,7 @@ fn full_div_rem(self, other: $ty, borrow: $ty) -> ($ty, $ty) {
         /// copying it recklessly may result in the performance hit.
         /// Thus this is intentionally not `Copy`.
         ///
-        /// All operations available to bignums panic in the case of over/underflows.
+        /// All operations available to bignums panic in the case of overflows.
         /// The caller is responsible to use large enough bignum types.
         pub struct $name {
             /// One plus the offset to the maximum "digit" in use.

src/libcore/num/mod.rs

@@ -402,7 +402,7 @@ pub fn checked_add(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer subtraction. Computes `self - rhs`, returning
-        /// `None` if underflow occurred.
+        /// `None` if overflow occurred.
         ///
         /// # Examples
         ///
@@ -420,7 +420,7 @@ pub fn checked_sub(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer multiplication. Computes `self * rhs`, returning
-        /// `None` if underflow or overflow occurred.
+        /// `None` if overflow occurred.
         ///
         /// # Examples
         ///
@@ -438,7 +438,7 @@ pub fn checked_mul(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer division. Computes `self / rhs`, returning `None`
-        /// if `rhs == 0` or the operation results in underflow or overflow.
+        /// if `rhs == 0` or the operation results in overflow.
         ///
         /// # Examples
         ///
@@ -460,7 +460,7 @@ pub fn checked_div(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer remainder. Computes `self % rhs`, returning `None`
-        /// if `rhs == 0` or the operation results in underflow or overflow.
+        /// if `rhs == 0` or the operation results in overflow.
         ///
         /// # Examples
         ///
@@ -1598,7 +1598,7 @@ pub fn checked_add(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer subtraction. Computes `self - rhs`, returning
-        /// `None` if underflow occurred.
+        /// `None` if overflow occurred.
         ///
         /// # Examples
         ///
@@ -1616,7 +1616,7 @@ pub fn checked_sub(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer multiplication. Computes `self * rhs`, returning
-        /// `None` if underflow or overflow occurred.
+        /// `None` if overflow occurred.
         ///
         /// # Examples
         ///
@@ -1634,7 +1634,7 @@ pub fn checked_mul(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer division. Computes `self / rhs`, returning `None`
-        /// if `rhs == 0` or the operation results in underflow or overflow.
+        /// if `rhs == 0` or the operation results in overflow.
         ///
         /// # Examples
         ///
@@ -1654,7 +1654,7 @@ pub fn checked_div(self, rhs: Self) -> Option<Self> {
         }
 
         /// Checked integer remainder. Computes `self % rhs`, returning `None`
-        /// if `rhs == 0` or the operation results in underflow or overflow.
+        /// if `rhs == 0` or the operation results in overflow.
         ///
         /// # Examples
         ///

src/libcore/ptr.rs

@@ -581,8 +581,7 @@ pub unsafe fn as_ref<'a>(self) -> Option<&'a T> {
     /// * Both the starting and resulting pointer must be either in bounds or one
     ///   byte past the end of an allocated object.
     ///
-    /// * The computed offset, **in bytes**, cannot overflow or underflow an
-    ///   `isize`.
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
     /// * The offset being in bounds cannot rely on "wrapping around" the address
     ///   space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
@@ -714,8 +713,7 @@ pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized {
     /// * Both the starting and resulting pointer must be either in bounds or one
     ///   byte past the end of an allocated object.
     ///
-    /// * The computed offset, **in bytes**, cannot overflow or underflow an
-    ///   `isize`.
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
     /// * The offset being in bounds cannot rely on "wrapping around" the address
     ///   space. That is, the infinite-precision sum must fit in a `usize`.
@@ -1219,8 +1217,7 @@ pub unsafe fn as_ref<'a>(self) -> Option<&'a T> {
     /// * Both the starting and resulting pointer must be either in bounds or one
     ///   byte past the end of an allocated object.
     ///
-    /// * The computed offset, **in bytes**, cannot overflow or underflow an
-    ///   `isize`.
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
     /// * The offset being in bounds cannot rely on "wrapping around" the address
     ///   space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
@@ -1419,8 +1416,7 @@ pub fn align_offset(self, align: usize) -> usize {
     /// * Both the starting and resulting pointer must be either in bounds or one
     ///   byte past the end of an allocated object.
     ///
-    /// * The computed offset, **in bytes**, cannot overflow or underflow an
-    ///   `isize`.
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
     /// * The offset being in bounds cannot rely on "wrapping around" the address
     ///   space. That is, the infinite-precision sum must fit in a `usize`.

src/libstd/io/buffered.rs

@@ -263,7 +263,7 @@ impl<R: Seek> Seek for BufReader<R> {
     /// See `std::io::Seek` for more details.
     ///
     /// Note: In the edge case where you're seeking with `SeekFrom::Current(n)`
-    /// where `n` minus the internal buffer length underflows an `i64`, two
+    /// where `n` minus the internal buffer length overflows an `i64`, two
     /// seeks will be performed instead of one. If the second seek returns
     /// `Err`, the underlying reader will be left at the same position it would
     /// have if you seeked to `SeekFrom::Current(0)`.

src/libstd/time/duration.rs

@@ -290,7 +290,7 @@ pub fn checked_add(self, rhs: Duration) -> Option<Duration> {
     }
 
     /// Checked `Duration` subtraction. Computes `self - other`, returning [`None`]
-    /// if the result would be negative or if underflow occurred.
+    /// if the result would be negative or if overflow occurred.
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
     ///