bug#24870: 26.0.50; parse-partial-sexp ignores comment-end

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Matt Armstrong <marmstrong@google.com> writes:

> Andreas Röhler <andreas.roehler@easy-emacs.de> writes:
>
>> On 30.11.2016 10:10, Matt Armstrong wrote:
>>> Andreas Röhler <andreas.roehler@easy-emacs.de> writes:
>>>> haskell-mode, at EOB: --- {- To explore this file: -} asdf = --- 
>>>> parse-partial-sexp thinks being inside a paren - see attachment. GNU 
>>>> Emacs 26.0.50.1 (i686-pc-linux-gnu, GTK+ Version 3.14.5) of 2016-10-11 
>>> Hi Andreas, Emacs does not have a haskell-mode, so this bug is 
>>> difficult to reproduce. It may be more appropriate to report this to 
>>> the haskell-mode maintainers for triage. They can figure out if it is 
>>> a problem that should be fixed in haskell-mode itself, or a problem 
>>> with Emacs. Alternatively, can you provide a series of clear 
>>> instructions to reproduce the problem in a fresh Emacs started without 
>>> your customizations? For example, begin by running "emacs -Q" and go 
>>> from there. Your attached .png presents a buffer called 
>>> *parse-partial-sexp-output*, but it is not clear how this was 
>>> generated. Thanks
>> Hi Matt,
>>
>> checked that with help of the haskell-mode folks already.
>> https://github.com/haskell/haskell-mode/issues/1459
>
> Thanks.  For reference, this is what you have said on the github bug:
>
> Seems a bug of
> GNU Emacs 26.0.50.1 (i686-pc-linux-gnu, GTK+ Version 3.14.5) of 2016-11-15
> Does not exist at
> GNU Emacs 25.1.90.1 (i686-pc-linux-gnu, GTK+ Version 3.14.5) of 2016-11-29
>
>
>> As it's nice at current pretest Emacs, concluded a bug in trunk.
>> Here a shortened recipe. Put code below in a buffer:
>> ||
>> |{- Just a comment: -}|
>>
>> M-x haskell-mode RET
>
> Note that haskell-mode is not part of Emacs.  Ideally, your steps to
> reproduce that begin with running "emacs -Q".  Emacs maintainers that
> might not also be Haskell hackers will appreciate it.  :)
>
> Also, can you describe the visible symptom that caused you to begin
> looking at syntax-ppss and parse-partial-sexp?  That description may
> help me or others spot similarities with other reported bugs.
>
> (I must say that I am not an Emacs expert, and I do not usually reply to
> Emacs bugs.  I looked at a few bugs last night as a way to help
> maintainers triage the "easy" bugs.  It does not look like this bug is
> easy!)

This seems similar to #24767.