From 51024996015ea25534be0b45c703e18cc97fceaa Mon Sep 17 00:00:00 2001
From: "Pedro F. Giffuni" <pfg@FreeBSD.org>
Date: Tue, 7 Aug 2018 14:47:39 +0000
Subject: [PATCH] sed(1): partial fix for the case of the regex delimited with
 '['.

We don't generally support the weird case of regular expresions delimited
by an opening square bracket ('[') but POSIX says that inside
bracket expressions, escaping is not possible and both '[' and '\'
represent themselves.

PR:		230198 (exp-run)
Obtained from:	OpenBSD
---
 usr.bin/sed/compile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/usr.bin/sed/compile.c b/usr.bin/sed/compile.c
index 4427faeff4a2..df64a5c598c2 100644
--- a/usr.bin/sed/compile.c
+++ b/usr.bin/sed/compile.c
@@ -393,11 +393,11 @@ compile_delimited(char *p, char *d, int is_tr)
 			if ((d = compile_ccl(&p, d)) == NULL)
 				errx(1, "%lu: %s: unbalanced brackets ([])", linenum, fname);
 			continue;
+		} else if (*p == '\\' && p[1] == c) {
+			p++;
 		} else if (*p == '\\' && p[1] == '[') {
 			*d++ = *p++;
-		} else if (*p == '\\' && p[1] == c)
-			p++;
-		else if (*p == '\\' && p[1] == 'n') {
+		} else if (*p == '\\' && p[1] == 'n') {
 			*d++ = '\n';
 			p += 2;
 			continue;