Re: maintain flymake.el

[Jan Djärv]

Hello.

16 dec 2013 kl. 17:48 skrev Sebastian Wiesner <address@hidden>:

> 2013/12/16 Jan Djärv <address@hidden>:
>> Hello.
>> 
>> 16 dec 2013 kl. 15:32 skrev Ted Zlatanov <address@hidden>:
>> 
>>> On Sun, 15 Dec 2013 19:31:46 +0100 Sebastian Wiesner <address@hidden> wrote:
>>> 
>>> SW> 2013/12/14 Sebastian Wiesner <address@hidden>:
>>>>> I hope to finish the document by tomorrow evening, and will come back
>>>>> if it's done.
>>> 
>>> SW> I have completed the document now.  The final version is to be found
>>> SW> at https://github.com/flycheck/flycheck/wiki/Flycheck-versus-Flymake.
>>> SW> It's a thorough write-up of the differences and similarities between
>>> SW> Flycheck and Flymake, and probably also a comprehensive summary of the
>>> SW> current issues and weaknesses in Flymake.
>>> 
>>> SW> Again, it's probably unfairly biased towards Flycheck.  I tried my
>>> SW> best to be neutral, but I consider Flycheck superior and think that
>>> SW> the design and implementation of Flymake are somewhat broken, so I may
>>> SW> have failed to properly account for Flymake's features and strengths.
>>> SW> Please excuse this, and feel free to correct any mistakes I may have
>>> SW> made.
>>> 
>>> SW> Please also suggest improvements, such as additional aspects which
>>> SW> should be covered, or report issues, such as missing details in the
>>> SW> comparsion.
>> 
>> 
>> You are missing the big think that separates flymake and flycheck. Flymake 
>> uses makefiles, flycheck does not.  This means to be able to use flycheck on 
>> a large C/C++ project you have to maintain includes and defined in both 
>> makefiles and as lisp variables for flycheck.  Flymake does not have that 
>> problem, you just add one rule for it in the makefiles, re-using all 
>> definitions and include paths.
>> 
>> This is really a showstopper for flycheck, even if it has some nicer GUI 
>> stuff.  It is really only usable for small projects.
> 
> You can easily define your own syntax checker:
> 
> (flycheck-define-checker 'c-makefile-checker
>  :command ("make" "CC=clang" "build")
>  :error-patterns
>  ((info line-start (file-name) ":" line ":" column
>            ": note: " (message) line-end)
>   (warning line-start (file-name) ":" line ":" column
>            ": warning: " (message) line-end)
>   (error line-start (file-name) ":" line ":" column
>          ": " (or "fatal error" "error") ": " (message) line-end))
>  :modes (c-mode)
>  :predicate (lambda () (not (buffer-modified-p)))
> 

"Easy" is in the eye of the beholder.
 
> The error patterns are for Clang.  Adapt the accordingly, if you are
> using a different compiler.  The predicate makes sure that Flycheck
> only uses this syntax checker after the buffer was saved, because
> calling out to the build system after every change is probably not a
> good idea.
> 
> Then just register the new syntax checker, and disable the built-in
> Clang checker to avoid conflicting error messages:
> 
> (add-to-list 'flycheck-checkers 'c-make-file-checker)
> (setq-default flycheck-disabled-checkers '(c/c++-clang))
> 
> Feel free to copy this to your "init.el".
> 
> Flycheck does not include this syntax checker for two reasons:
> 
> - No one contributed it :)
> - It's hard, if not impossible, to get this right in a generic way.

Yet that is what compile mode tries to do.  So use those.

> 
> There is simply no standard for Makefiles and compiler messages, so
> Flycheck has no chance to call a Makefile in a portable way, that
> works identically across all build systems, from CMake and Autotools,
> to custom ad-hoc Makefiles, which don't even use generic rules, to the
> strangest and most exotic compiler flags, especially if it does not
> want to conduct a full build (which could take minutes, if not ours),
> but only a syntax check of the file being edited.
> 
> But again, you know your projects, and nothing stops you from
> definining your own syntax checker just for these projects.  Try it.
> Really.  It's easy.

I won't bother as you stated that Flycheck won't be part of Emacs.

        Jan D.