Add function `string-common-prefix'scratch/string-common-prefix

* lisp/subr.el: (string-common-prefix): New function.

* etc/NEWS:
* doc/lispref/strings.texi:
* doc/lispref/minibuf.texi:
* lisp/emacs-lisp/shortdoc.el:
Documentation.

1 files changed, 6 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 2cb1978738e..256c8ab139d 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -3879,6 +3879,12 @@ It offers a more concise way to create a completion table with metadata.
 ** 'all-completions' and 'unintern' no longer support old calling conventions.
 
 +++
+** New function 'string-common-prefix'.
+Return the longest common prefix from a collection of strings.  This
+function is similar to 'try-completion', but it returns a string in all
+cases.
+
++++
 ** New symbol property 'find-function-type-alist' used by 'find-function' etc.
 Macros that define an object in a way that makes the object's name and
 the macro call site defining the object hard to associate can add an