The check for empty patterns and patterns matching the empty string

in commitid 1004D8283F068C41C3C was bogus; it fixed Jb_boin’s issue
but izabers’s 「var=foo; echo "${var/*/x}"」 was broken; in fact we
only want to not do the looping for // if the pattern matches much.

Also, fix a spelling mistake in the manpage and change some wording
to also work with associative arrays (in the future; no change).

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.693 2015/04/29 20:44:32 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.694 2015/05/23 17:43:18 tg Exp $
 # -*- mode: sh -*-
 #-
 # Copyright © 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
@@ -30,7 +30,7 @@
 # (2013/12/02 20:39:44) http://openbsd.cs.toronto.edu/cgi-bin/cvsweb/src/regress/bin/ksh/?sortby=date
 
 expected-stdout:
-	@(#)MIRBSD KSH R51 2015/04/29
+	@(#)MIRBSD KSH R51 2015/05/23
 description:
 	Check version of shell.
 stdin:
@@ -39,7 +39,7 @@ name: KSH_VERSION
 category: shell:legacy-no
 ---
 expected-stdout:
-	@(#)LEGACY KSH R51 2015/04/29
+	@(#)LEGACY KSH R51 2015/05/23
 description:
 	Check version of legacy shell.
 stdin:

eval.c

@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/eval.c,v 1.168 2015/04/29 18:32:42 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/eval.c,v 1.169 2015/05/23 17:43:19 tg Exp $");
 
 /*
  * string expansion
@@ -528,43 +528,27 @@ expand(
 						afree(tpat0, ATEMP);
 
 						/* check for special cases */
-						d = str_val(st->var);
 						switch (*pat) {
 						case '#':
-							/* anchor at begin */
-							tpat0 = pat + 1;
-							tpat1 = rrep;
-							tpat2 = d;
-							break;
 						case '%':
-							/* anchor at end */
 							tpat0 = pat + 1;
-							tpat1 = d;
-							tpat2 = rrep;
 							break;
 						case '\0':
-							/* empty pattern */
+							/* empty pattern, reject */
 							goto no_repl;
 						default:
 							tpat0 = pat;
-							/* silence gcc */
-							tpat1 = tpat2 = NULL;
 						}
 						if (gmatchx(null, tpat0, false)) {
 							/*
-							 * pattern matches
+							 * pattern matches empty
-							 * the empty string
+							 * string => don't loop
 							 */
-							if (tpat0 == pat)
+							stype &= ~0x80;
-								goto no_repl;
-							/* but is anchored */
-							s = shf_smprintf("%s%s",
-							    tpat1, tpat2);
-							goto do_repl;
 						}
 
 						/* prepare string on which to work */
-						strdupx(s, d, ATEMP);
+						strdupx(s, str_val(st->var), ATEMP);
 						sbeg = s;
 
 						/* first see if we have any match at all */
@@ -622,7 +606,6 @@ expand(
 							goto again_repl;
  end_repl:
 						afree(tpat1, ATEMP);
- do_repl:
 						x.str = s;
  no_repl:
 						afree(pat, ATEMP);

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.366 2015/04/29 20:44:36 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.367 2015/05/23 17:43:20 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.159 2015/03/25 12:10:52 jca Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
@@ -74,7 +74,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: April 29 2015 $
+.Dd $Mdocdate: May 23 2015 $
 .\"
 .\" Check which macro package we use, and do other -mdoc setup.
 .\"
@@ -1538,7 +1538,9 @@ is not needed, it is not evaluated.
 .Pp
 The following forms of parameter substitution can also be used (if
 .Ar name
-is an array, its element #0 will be substituted in a scalar context):
+is an array, the element with the key
+.Dq 0
+will be substituted in scalar context):
 .Pp
 .Bl -tag -width Ds -compact
 .It Pf ${# Ns Ar name Ns \&}
@@ -1628,7 +1630,7 @@ Cannot be applied to a vector.
 .Pf // Ar pattern / Ar string No }
 .Xc
 .Sm on
-Like ${..#..} substitution, but it replaces the longest match of
+Similar to ${..##..} substitution, but it replaces the longest match of
 .Ar pattern ,
 anchored anywhere in the value, with
 .Ar string .
@@ -1639,17 +1641,17 @@ begins with
 it is anchored at the beginning of the value; if it begins with
 .Ql % ,
 it is anchored at the end.
-Patterns that are empty or consist only of wildcards are invalid.
+Empty patterns cause no replacement to happen.
-A single
+A single leading
 .Ql /
-replaces the first occurence of the search
+or use of a pattern that matches the empty string causes the
-.Ar pattern ,
+replacement to happen only once; two leading slashes cause
-and two of them replace all occurences.
+all occurrences of matches in the value to be replaced.
-If
+If the trailing
 .Pf / Ar string
-is omitted, the
+is omitted, any matches of
 .Ar pattern
-is replaced by the empty string, i.e. deleted.
+are replaced by the empty string, i.e. deleted.
 Cannot be applied to a vector.
 Inefficiently implemented, may be slow.
 .Pp
@@ -2010,7 +2012,7 @@ You can tell the shell not to count certain
 sequences (such as escape codes) by prefixing your prompt with a
 character (such as Ctrl-A) followed by a carriage return and then delimiting
 the escape codes with this character.
-Any occurences of that character in the prompt are not printed.
+Any occurrences of that character in the prompt are not printed.
 By the way, don't blame me for
 this hack; it's derived from the original
 .Xr ksh88 1 ,

sh.h

@@ -169,9 +169,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.729 2015/04/29 20:44:37 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.730 2015/05/23 17:43:22 tg Exp $");
 #endif
-#define MKSH_VERSION "R51 2015/04/29"
+#define MKSH_VERSION "R51 2015/05/23"
 
 /* arithmetic types: C implementation */
 #if !HAVE_CAN_INTTYPES