bug#39290: [PATCH] Correct regexp for flags in 'format' doc string

["Mattias Engdegård" <mattiase@acm.org>]

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The doc string for 'format' contains

  where field is [0-9]+ followed by a literal dollar "$", flags is
  [+ #-0]+, width is [0-9]+, and precision is a literal period "."
  followed by [0-9]+.

The spec for flags isn't a correct regexp; the hyphen should be last.  This matters, because people copy it into their code without thinking (observed in the wild).

Patch acceptable for emacs-27?


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From 5245a818d978a96c17c3ec7b99d93e32a07f90e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Sun, 26 Jan 2020 15:07:45 +0100
Subject: [PATCH] Correct regexp for flags in `format' doc string

* src/editfns.c (Fformat): Use the correct regexp for describing the
flags in a %-sequence (place the hyphen last).
---
 src/editfns.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/editfns.c b/src/editfns.c
index 4e35784e55..3f1b3aa4b7 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -3031,7 +3031,7 @@ DEFUN ("format", Fformat, Sformat, 1, MANY, 0,
   %<field><flags><width><precision>character
 
 where field is [0-9]+ followed by a literal dollar "$", flags is
-[+ #-0]+, width is [0-9]+, and precision is a literal period "."
+[+ #0-]+, width is [0-9]+, and precision is a literal period "."
 followed by [0-9]+.
 
 If a %-sequence is numbered with a field with positive value N, the
-- 
2.21.0 (Apple Git-122.2)