emacs-31 9448f8e3dd3 1/2: ; Improve documentation of 'char-uppercase-p'

branch: emacs-31
commit 9448f8e3dd33bf38beb9c9dd7286af7823244dbb
Author: Eli Zaretskii <[email protected]>
Commit: Eli Zaretskii <[email protected]>

    ; Improve documentation of 'char-uppercase-p'
    
    * doc/lispref/display.texi (Size of Displayed Text):
    * lisp/simple.el (char-uppercase-p): Clarify "uppercase
    character".
---
 doc/lispref/display.texi | 6 ++++--
 lisp/simple.el           | 4 +++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index e1b46d51489..5f3eb0cf2c7 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -2214,8 +2214,10 @@ Tables}).  The width of a tab character is usually @code{tab-width}
 @end defun
 
 @defun char-uppercase-p char
-Return non-@code{nil} if @var{char} is an uppercase character
-according to Unicode.
+Return non-@code{nil} if @var{char} is an upper-case character
+according to Unicode.  Note that a character is considered to be
+upper-case if the Unicode Standard defines a corresponding lower-case
+character.
 @end defun
 
 @defun string-width string &optional from to
diff --git a/lisp/simple.el b/lisp/simple.el
index 7ea287fd6ff..5b7f5f30058 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -6684,8 +6684,10 @@ and KILLP is t if a prefix arg was specified."
 
 (defun char-uppercase-p (char)
   "Return non-nil if CHAR is an upper-case character.
+A character is considered upper-case if there's a correspoding
+lower-case character.
 If the Unicode tables are not yet available, e.g. during bootstrap,
-then gives correct answers only for ASCII characters."
+this function gives correct return values only for ASCII characters."
   (cond ((unicode-property-table-internal 'lowercase)
          (characterp (get-char-code-property char 'lowercase)))
         ((<= ?A char ?Z))))