Misleading error message for unmatched template conditionals

Question

Misleading error message for unmatched template conditionals

tstenner opened this issue 5 years ago · 8 comments

In pandoc 2.5, a template with an unmatched template conditional causes pandoc to fail with an error:

$ cat test.md 
Foo.
$endif$

$ echo 'Test' | pandoc --template=test.md
[WARNING] This document format requires a nonempty [...]
"template" (line 2, column 7):
unexpected "$"

Any non-keyword (e.g. $endi$ ) is replaced by an empty string and a document is created. While the error message indicates the correct position, it should also include the keyword, i.e. "template" (line 2, column 7): unexpected "$else$"

Answer 1 · 2019-01-14T20:38:46.000Z

jgm/doctemplates is the library used for parsing templates, so any improvements would need to go there.

Answer 2 · 2019-01-15T12:00:20.000Z

Right, I see. Could you move this issue to jgm/doctemplates or should I open a new issue?

Answer 3 · 2019-01-15T22:55:07.000Z

I can move it...

Answer 4 · 2019-01-18T00:30:35.000Z

Note: no document is created. Try -o test.out; you'll see there is no test.out.

So you're getting an error message about invalid syntax in the template, which points to the line and column where the error is. All this is just right. The only thing that could be improved, as far as I can see, is that it could say unexpected "$endif$" instead of unexpected "$". Am I missing something?

Answer 5 · 2019-01-24T08:44:10.000Z

The only thing that could be improved, as far as I can see, is that it could say unexpected "$endif$" instead of unexpected "$"

That's correct. It's great the correct location is indicated, but if the error message indicated that a $ would be allowed, just not a lone $endif$ it'd be easier to correct the mistake in the template.

Answer 6 · 2019-01-24T22:14:30.000Z

Tristan Stenner <notifications@github.com> writes:

> The only thing that could be improved, as far as I can see, is that it could say unexpected "$endif$" instead of unexpected "$" That's correct. It's great the correct location is indicated, but if the error message indicated that a `$` would be allowed, just not a lone `$endif$` it'd be easier to correct the mistake in the template.

Well, actually a lone `$` would not be allowed. Literal `$` must be escaped as `$$`.

Answer 7 · 2019-01-25T09:33:59.000Z

Well, actually a lone $ would not be allowed.

You're right, but a single $ also has a good error message:

$endif$
      ^    -> error: unexpected "$"
      ^       maybe "error: $endif$ without $if$"?

$endi$        Ok, evaluates to empty string

Test $foo without closing dollar sign
         ^    -> error: unexpected " ", expecting "." or "$"

Answer 8 · 2019-01-25T23:48:46.000Z

Yes, I agree that the messages could be somewhat better.
This is a low priority for me, though, compared to other things.
I'll move this to doctemplates and perhaps someone will take it up.