IEEE Std 1003.1, 2004 Edition states:

"The escape sequence '\n' shall match a <newline> embedded in
the pattern space."

It is unclear whether this also applies to a \n embedded in a
character class.  Disable the existing handling of \n in a character
class following Mac OS X, GNU sed version 4.1.5 with --posix, and
SunOS 5.10 /usr/bin/sed.

Pointed by:	Marius Strobl
Obtained from:	Mac OS X

tools/regression/usr.bin/sed/multitest.t

@@ -449,6 +449,9 @@ u2/g' lines1
 	mark '8.21'
 	echo 'a\b(c' |
 	$SED 'y%ABCDEFGHIJKLMNOPQRSTUVWXYZ, /\\()"%abcdefghijklmnopqrstuvwxyz,------%'
+	COMMENT='\n in a character class and a BRE'
+	mark '8.22' ; (echo 1; echo 2) | $SED -n '1{;N;s/[\n]/X/;p;}'
+	mark '8.23' ; (echo 1; echo 2) | $SED -n '1{;N;s/\n/X/;p;}'
 }
 
 test_error()

tools/regression/usr.bin/sed/regress.multitest.out/8.22

@@ -0,0 +1,2 @@
+1
+2

tools/regression/usr.bin/sed/regress.multitest.out/8.23

@@ -0,0 +1 @@
+1X2

usr.bin/sed/compile.c

@@ -432,8 +432,7 @@ compile_ccl(char **sp, char *t)
 			for (c = *s; (*t = *s) != ']' || c != d; s++, t++)
 				if ((c = *s) == '\0')
 					return NULL;
-		} else if (*s == '\\' && s[1] == 'n')
-			    *t = '\n', s++;
+		}
 	return (*s == ']') ? *sp = ++s, ++t : NULL;
 }