bug#24697: 25.1; find-lisp-object-file-name may return wrong locations

[Alex]

Dmitry Gutov <dgutov@yandex.ru> writes:

> On 6/18/17 1:26 AM, Alex wrote:
>
>> The first and last of these are fixed by the following diff.
>>
>> ...
>>
>>
>> The second is a bit odder. For some reason, find-lisp-object-file-name
>> searches for an internal function definition using TYPE instead of
>> OBJECT. I would have expected it to use OBJECT like the rest of the
>> tests do. I see no reason for the current behaviour.
>
> Thanks. Do you think you can write test cases for these problems? There are 
> some
> existing ones in test/lisp/help-fns-tests.el.

Sure, I've attached a patch below for the simple cases. As I couldn't
find a satisfactory way to make a temporary face, I just made an
uninterned symbol that find-lisp-object-file-name would treat as an
internal variable.

>> Either the documentation should be changed to clearly indicate the
>> current behaviour, or the function should be changed so that OBJECTs for
>> which (subrp (symbol-function OBJECT)) returns t should return
>> 'C-source'.
>
> With a test case, you might also find it easier to make a choice regarding 
> this
> problem.

I'm not sure. I still don't understand why the design decision was made.
I suppose one benefit is that one can search explicitly for internal
functions rather than lisp functions, but the function could have just
accepted 'subr instead of 'defun to do that.

Perhaps the current use of searching with TYPE should be left in for
backwards compatibility (a Github search shows at least 2 instances of
3rd-party code that makes use of that behaviour).

For instance, here's how you find mapatoms' file:

  (find-lisp-object-file-name 'mapatoms (symbol-function 'mapatoms))

You should just be able to do the following:

  (find-lisp-object-file-name 'mapatoms 'defun)

Or without searching for lisp functions named mapatoms first:

  (find-lisp-object-file-name 'mapatoms 'subr)

What do you think?

0001-Only-search-for-a-variable-when-instructed.patch
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