Document why `str.to_{lower,upper}case` return `String`

Fixes #39201.
This commit is contained in:
Tobias Bucher 2017-03-08 00:06:09 +01:00
parent b04ebef432
commit f3a2f90c88
1 changed files with 8 additions and 0 deletions

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@ -1646,6 +1646,10 @@ impl str {
/// 'Lowercase' is defined according to the terms of the Unicode Derived Core Property
/// `Lowercase`.
///
/// Since some characters can expand into multiple characters when changing
/// the case, this function returns a [`String`] instead of modifying the
/// parameter in-place.
///
/// [`String`]: string/struct.String.html
///
/// # Examples
@ -1718,6 +1722,10 @@ impl str {
/// 'Uppercase' is defined according to the terms of the Unicode Derived Core Property
/// `Uppercase`.
///
/// Since some characters can expand into multiple characters when changing
/// the case, this function returns a [`String`] instead of modifying the
/// parameter in-place.
///
/// [`String`]: string/struct.String.html
///
/// # Examples