Re: ${var+set}, ${var:+nonempty} broken in current git

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

On Wed, Sep 05, 2018 at 06:21:36PM +0200, Martijn Dekker wrote:
> 
> With this patch applied, the following breakage still occurs:
> $ src/dash -u -c 'unset foo bar; echo ${foo+${bar}}'
> src/dash: 1: bar: parameter not set
> (expected: empty line, no error)
> ...which seems to suggest that ${bar} is evaluated even though foo is unset.

This patch should fix it.

---8<---
Subject: expand: Only call varunset when EXP_DISCARD is not set

When EXP_DISCARD is set, we must not generate a real error such
as varunset because we're only parsing the text and not evaluating
it.

For example:

	$ dash -u -c 'unset foo bar; echo ${foo+${bar}}'
	dash: 1: bar: parameter not set

This should not fail.

This patch fixes it by checking the EXP_DISCARD bit in the caller
flag before calling varunset.

Reported-by: Martijn Dekker <martijn@xxxxxxxx>
Fixes: 3cd538634f71 ("expand: Do not reprocess data when...")
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

diff --git a/src/expand.c b/src/expand.c
index e890052..d3e66c8 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -744,7 +744,7 @@ again:
 		goto again;
 	}
 
-	if (discard && uflag)
+	if ((discard & ~flag) && uflag)
 		varunset(p, var, 0, 0);
 
 	if (subtype == VSLENGTH) {
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt