From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Sat, 3 Aug 2019 13:29:04 +0000 (+0200)
Subject: Clarify Freplace_match logic
X-Git-Tag: emacs-27.0.90~1734
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=f77a39514687f57c947e9105172c3d3821a759cc;p=emacs.git

Clarify Freplace_match logic

* src/search.c (Freplace_match): Add some doc strings to clarify
the logic and do a minor clean up (bug#19208).
---

diff --git a/src/search.c b/src/search.c
index fa574959fb4..2fa8b277195 100644
--- a/src/search.c
+++ b/src/search.c
@@ -2397,11 +2397,15 @@ since only regular expressions have distinguished subexpressions.  */)
   else
     {
       CHECK_FIXNUM (subexp);
-      if (! (0 <= XFIXNUM (subexp) && XFIXNUM (subexp) < search_regs.num_regs))
-	args_out_of_range (subexp, make_fixnum (search_regs.num_regs));
       sub = XFIXNUM (subexp);
+      /* Sanity check to see whether the subexp is larger than the
+	 allowed number of sub-regexps. */
+      if (sub >= 0 && sub > search_regs.num_regs)
+	args_out_of_range (subexp, make_fixnum (search_regs.num_regs));
     }
 
+  /* Sanity check to see whether the text to replace is present in the
+     buffer/string. */
   if (NILP (string))
     {
       if (search_regs.start[sub] < BEGV