bug#23053: 25.0.92; error in cc-mode when editing C# file with a generic class inheritance

["Jostein Kjønigsen" <jostein@secure.kjonigsen.net>]

On Mon, Mar 21, 2016, at 01:26 PM, Alan Mackenzie wrote:
> If so, could you possibly give me details of the
> version of the emacs-25 branch you saw it in, and any other details I'd
> need to reproduce it.  Thanks!

I've been tracking Emacs git master. Currently I'm at this point:

> commit 58862751bde2611d9ea99a33ecb5b0c13a7513b9
> Author: Glenn Morris <rgm@gnu.org>
> Date:   Thu Mar 17 00:14:11 2016 -0700

After each "git pull", I've done a "make distclean && make".

> Can we be absolutely clear here, please.  Have you observed this bug in
> Java Mode yourself?

Yes. I've created a new file called test.java with the following
contents:

> package Test;
> 
> public class A extends B<T>$

Pressing enter at this point will trigger a similar error, and the same
will typing { following that enter.

> I suspect the interface between CC Mode and csharp-mode.  :-)
> 
> My working hypothesis is that the compiled csharp-mode.elc was compiled
> on an earlier revision of the emacs-25 branch, hence didn't pick up a
> newly introduced c-lang-defvar properly, thus leaving its value at nil.
> This nil value is what triggered the error in
> c-forward-<>-arglist-recur.

That's a good theory and I decided to completely wiping csharp-mode and
reevaluating it inside Emacs to verify that stale data is not the cause
of the errors.

I'm still getting "wrong argument: stringp, nil" everywhere when
pressing enter interactively inside Emacs csharp-mode buffers.

I therefore tried to look into the build-system to see what it reports.

Byte-compiling csharp-mode triggers a warning which so far haven't been
an
issue for csharp-mode:

> $ make csharp-mode.elc
> ...
> csharp-mode.el:1772:17:Warning: looking-back called with 1 argument, but
>     requires 2-3

Trying to run a "make test" of csharp-mode against git master, most of
the tests breaks:

> Test indentation-rules-should-be-as-specified-in-test-doc backtrace:
>   c-forward-label()
>   c-guess-basic-syntax()
>   c-indent-region(1 1390)
>   indent-region(1 1390)
>   (let* ((buffer (find-file "test-files/indentation-tests.cs")) (orig-
>   (lambda nil (let* ((buffer (find-file "test-files/indentation-tests.
>   ert--run-test-internal([cl-struct-ert--test-execution-info [cl-struc
>   ert-run-test([cl-struct-ert-test indentation-rules-should-be-as-spec
>   ert-run-or-rerun-test([cl-struct-ert--stats t [[cl-struct-ert-test a
>   ert-run-tests(t #[385 "\306\307\"\203G\211\211G\310U\203\211@\20
>   ert-run-tests-batch(nil)
>   ert-run-tests-batch-and-exit()
>   command-line-1(("-L" "." "-l" "csharp-mode-tests.el" "-f" "ert-run-t
>   command-line()
>   normal-top-level()
> Test indentation-rules-should-be-as-specified-in-test-doc condition:
>     (wrong-type-argument stringp nil)
>    FAILED  15/15  indentation-rules-should-be-as-specified-in-test-doc

I haven't looked into Saulius's C# file to reproduce this issue, so I
can't say if that is why you cannot reproduce or not.

Are the changes between between Emacs-25 and master so significant that
they could the big differences between our observations? I find that
hard to believe.

Anyway, something somewhere is clearly broken, and the faster we can
find out what, the better.

If you need more input, more theories tested, or more help understanding
any part of my setup, let me know. I'll try to provide all the info I
can.

-- 
Jostein Kjønigsen
jostein@kjonigsen.net / jostein@secure.kjonigsen.net