From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-workers-return-40322-mason-zsh=primenet.com.au@zsh.org>
Received: (qmail 29657 invoked by alias); 10 Jan 2017 15:35:03 -0000
Mailing-List: contact zsh-workers-help@zsh.org; run by ezmlm
Precedence: bulk
X-No-Archive: yes
List-Id: Zsh Workers List <zsh-workers.zsh.org>
List-Post: <mailto:zsh-workers@zsh.org>
List-Help: <mailto:zsh-workers-help@zsh.org>
X-Seq: 40322
Received: (qmail 14519 invoked from network); 10 Jan 2017 15:35:03 -0000
X-Qmail-Scanner-Diagnostics: from out1-smtp.messagingengine.com by f.primenet.com.au (envelope-from <ynnor@mm.st>, uid 7791) with qmail-scanner-2.11 
 (clamdscan: 0.99.2/21882. spamassassin: 3.4.1.  
 Clear:RC:0(66.111.4.25):SA:0(-0.7/5.0):. 
 Processed in 0.38327 secs); 10 Jan 2017 15:35:03 -0000
X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on f.primenet.com.au
X-Spam-Level: 
X-Spam-Status: No, score=-0.7 required=5.0 tests=FREEMAIL_FROM,
	RCVD_IN_DNSWL_LOW,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_PASS,T_DKIM_INVALID
	autolearn=unavailable autolearn_force=no version=3.4.1
X-Envelope-From: ynnor@mm.st
X-Qmail-Scanner-Mime-Attachments: |
X-Qmail-Scanner-Zip-Files: |
Received-SPF: pass (ns1.primenet.com.au: SPF record at spf.messagingengine.com designates 66.111.4.25 as permitted sender)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=mm.st; h=
	content-transfer-encoding:content-type:date:from:message-id
	:mime-version:subject:to:x-me-sender:x-me-sender:x-sasl-enc; s=
	mesmtp; bh=sp0ooFjQDjbr+6TdASooGUBXK3I=; b=Jp1BKMyHTNowyZwKOwrhR
	GVvc/lbBNd4s4mtsUy6PydIxw/LU1UFLdAxoMcoe8x4qRTKGhLaQSpPo1oecfE10
	6R2wVYdicUXsLIqNM6lvt9GDw0qpkA4+qfWxXnh0mcNRNk/OpQIuo+CSfSMaeNXz
	VRnSMF8DXNrgGc+Lm1mBpY=
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=
	messagingengine.com; h=content-transfer-encoding:content-type
	:date:from:message-id:mime-version:subject:to:x-me-sender
	:x-me-sender:x-sasl-enc; s=smtpout; bh=sp0ooFjQDjbr+6TdASooGUBXK
	3I=; b=VK9e5VbDDWd4yE2VbiI0rNxSqUY8i1VizoH+BP4q5aCXYosKZG2wLCsg3
	dp4ebT5NusGJ7L1/ywz0mYMrTNE38Rw4XkqxJMPbKh61qqU6pVEFOrMR86uLlVT1
	QFuJ1ajmLJvXjCgdW5mLePfJ/k90U/csVvTZtQ8oPW7y65FJRM=
X-ME-Sender: <xms:JP90WMCZhF5twG_KUMXf9V5AJftRON3oSjcbsZLHUW80eNBMa1YicA>
Message-Id: <1484062500.4181388.843189521.58854935@webmail.messagingengine.com>
From: Ronald Fischer <ynnor@mm.st>
To: zsh-workers@zsh.org
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="utf-8"
X-Mailer: MessagingEngine.com Webmail Interface - html
Date: Tue, 10 Jan 2017 16:35:00 +0100
Subject: Bug in parameter expansion with :-    ?

This expands correctly to a '+':

      ${unset_variable:-+}

This however doesn't expand to a '-', but to the empty string:

    ${unset_variable:--}

I didn't find anything in the man page which would explain this
behaviour.

A note aside: Bash expands in the latter case to a dash (-). 

My zsh version:

zsh 5.1.1 (x86_64-unknown-cygwin)


Ronald