Re: [PATCH] tests: avoid syntax triggering old dash bug

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 28, 2018, 04:45 UTC
Message-ID: <xmqqo9a9stbs.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <CAPig+cS-_m8RBsCME_Gj15EEs1tcFcGn0Acfvq4HgxKiL9PaHg@mail.gmail.com>

Eric Sunshine <sunshine@sunshineco.com> writes:

Show 16 quoted lines

> On Tue, Nov 27, 2018 at 11:43 AM Ævar Arnfjörð Bjarmason
> <avarab@gmail.com> wrote:
>> Avoid a bug in dash that's been fixed ever since its
>> ec2c84d ("[PARSER] Fix clobbering of checkkwd", 2011-03-15)[1] first
>> released with dash v0.5.7 in July 2011.
>
> Perhaps enhance the commit message to explain the nature of the bug
> itself. It is not at all obvious from reading the above or from
> looking at the diff itself what the actual problem is that the patch
> is fixing. (And it wasn't even immediately obvious by looking at the
> commit message of ec2c84d in the dash repository.) To help readers of
> this patch avoid re-introducing this problem or diagnose such a
> failure, it might be a good idea to give an example of the syntax
> which trips up old dash (i.e. a here-doc followed immediately by a
> {...} expression) and the actual error message 'Syntax error: "}"
> unexpected'.

Indeed. From the patch text, I would not have even guessed. I was wondering if there were interactions with "" and $() inside it.

If having {...} immediately after a here-doc is a problem, then the patch should not touch existing code at all, but instead insert a new line, perhaps like

	: avoid open brace immediately after here-doc for old dash

immediately before {...}; that would have made it easier to grok.

Show 11 quoted lines

>@@ -892,8 +892,9 @@ test_expect_success 'get --expiry-date' '
> 	1510348087
> 	0
> 	EOF
>+	date_valid1=$(git config --expiry-date date.valid1) &&
> 	{
>-		echo "$rel_out $(git config --expiry-date date.valid1)"
>+		echo "$rel_out $date_valid1"
> 		git config --expiry-date date.valid2 &&
> 		git config --expiry-date date.valid3 &&
> 		git config --expiry-date date.valid4 &&