20955: "unset foo" should return status 0 if foo was not set

ChangeLog

@@ -1,3 +1,8 @@
+2005-03-09  Peter Stephenson  <pws@csr.com>
+
+	* 20955: README, Src/builtin.c: "unset foo" should return
+	status 0 if foo was not set.
+
 2005-03-09  Motoi Washida  <a66@h8.dion.ne.jp>
 
 	* 20953: Completion/Unix/Command/_du: "du --version" tries to

README

@@ -24,78 +24,12 @@ details, see the documentation.
 Possible incompatibilities
 ---------------------------
 
-Currently the only known incompatibilities between 4.2.0 and later
-versions are minor:
+Since 4.2:
 
-
-Since 4.2.1:
-
-The "test" and "[" builtins now behave more like relevant Unix standards
-suggest they should.  Previously they were a simple front-end to the same
-tests used by zsh's "[[" syntax.  (The documentation was previously cagey
-about what "test" and "[" actually did.)  "[[" has always been the
-recommended way of implementing tests within zsh.
-
-In recent versions of zsh, typing the end-of-file (EOF) character
-(typically ^D, although this can be altered with the "stty" command)
-repeatedly in the line editor printed a warning message, but never exited the
-shell.  This was a departure from the traditional behaviour of zsh and
-other shells where the shell would exit after 10 EOFs.  The traditional
-behaviour has been restored.  Also, binding a user-defined editor command
-to the EOF character now suppresses the EOF behaviour inside the line
-editor; it is possible to emulate it if desired.
-
-
-From 4.2.0 to 4.2.1:
-
-IPv6 addresses must be specified in square brackets in the zftp module and
-the function system built on top of the zftp module.
-
-Special traps for pseudosignals ZERR, DEBUG and EXIT are no longer executed
-inside other traps.  Users may well have assumed this was the case anyway
-since the behaviour was not explicity documented.  See the NEWS file for
-more detail.
-
-By default, a maximum function depth of 4096 is now compiled into the
-shell.  This may be altered during configuration; see `Function depth' in
-INSTALL.
-
-
-Some particular differences you may notice between the 4.0 and 4.2 series
-of releases:
-
-The bash-compatibility zle functions described in the zshcontrib manual
-page have been removed as a more configurable set of editing widgets for
-dealing with words have been added.  The following code in .zshrc will set
-up for bash-style word handling:
-  autoload -U select-word-style
-  select-word-style bash
-
-The `=prog' facility for expanding command paths (provided the EQUALS
-option is enabled, as it is by default) no longer expands aliases.  It was
-felt this feature was underused and confusing.
-
-In 4.0, a literal `/' was quoted in the `src' text of a substitution of the
-form `${foo/src/rep}' or ${foo//src/rep} with two backslashes.  This was
-documented, but inconsistent with normal quoting conventions and poorly
-implemented.  The `/' now requires only one backslash to quote it whether
-or not the expression occurs in double quotes.  For example:
-  % foo=word/bird
-  % print ${foo/\//-} "${foo/\//+}"
-  word-bird word+bird
-Note also the following workaround which is valid in all versions of the
-shell that support this syntax:
-  % slash=/
-  % foo=word/bird
-  % print ${foo/$slash/-} "${foo/$slash/+}"
-
-In 4.0, the -M option to bindkey used the first non-option argument to
-specify the keymap, whereas it now uses an argument to the option.  Hence:
-  bindkey -M -R keymap a-z self-insert
-needs to be rewritten as
-  bindkey -M keymap -R a-z self-insert
-The following form works in both versions:
-  bindkey -R -M keymap a-z self-insert
+The "unset" builtin now does not regard the unsetting of non-existent
+variables as an error, so can still return status 0 (depending on the
+handling of other arguments).  This appears to be the standard shell
+behaviour.
 
 Documentation
 -------------

Src/builtin.c

@@ -2726,8 +2726,12 @@ bin_unset(char *name, char **argv, Options ops, int func)
 	pm = (Param) (paramtab == realparamtab ?
 		      gethashnode2(paramtab, s) :
 		      paramtab->getnode(paramtab, s));
+	/*
+	 * Unsetting an unset variable is not an error.
+	 * This appears to be reasonably standard behaviour.
+	 */
 	if (!pm)
-	    returnval = 1;
+	    continue;
 	else if ((pm->flags & PM_RESTRICTED) && isset(RESTRICTED)) {
 	    zerrnam(name, "%s: restricted", pm->nam, 0);
 	    returnval = 1;