bug#46256: [feature/native-comp] AOT eln files ignored if run from build tree

[Andy Moreton]

On Fri 05 Feb 2021, Andrea Corallo via "Bug reports for GNU Emacs, the Swiss 
army knife of text editors" wrote:

> Andy Moreton <andrewjmoreton@gmail.com> writes:
>
>> On Thu 04 Feb 2021, Andy Moreton wrote:
>>
>>> On Wed 03 Feb 2021, akrl--- via "Bug reports for GNU Emacs, the Swiss army 
>>> knife of text editors" wrote:
>>>>
>>>> Hi Andy,
>>>>
>>>> could you share the values of PATH_DUMPLOADSEARCH and
>>>> PATH_REL_LOADSEARCH from your epaths.h ?
>>>>
>>>> Thanks
>>>>
>>>>   Andrea
>>>
>>> Native branch checkout is in: "c:/emacs/git/emacs/native/"
>>>
>>> "c:/emacs/git/emacs/native/build/mingw64-x86_64-O2/src/epaths.h" contains:
>>>
>>> #define PATH_DUMPLOADSEARCH "C:/emacs/git/emacs/native/lisp"
>>> #define PATH_REL_LOADSEARCH "28.0.50/lisp"
>>
>> I've bootstrapped again after the recent hash shortening to ensure my build
>> is up to date, from commit 1f626e9662d8120acd5a937f847123cc2b8c6e31. The
>> paths above are unchanged.
>>
>> Running this from the build dir, I see messages like:
>>
>> error in process sentinel: Native elisp load failed: "file does not exists",
>>  
>> "c:/home/ajm/.emacs.d/eln-cache/28.0.50-e2ae3598/hl-line-e67628ec-664ef650.eln"
>>
>> This suggests that the AOT .eln files are not being found. It should find:
>
> AFAIK you should not get any error but the eln should be recompiled
> automatically.  I guess having updated the hash algorithm the startup is
> failing and you need to clean-up completely the build directory
> (especially native-lisp/), please retry after a git clean -xfd.

All of these experiments are done from a clean tree after "git clean
-xdf", and after removing ~/.emacs.d/eln-cache/*.

>> c:/emacs/git/emacs/native/build/mingw64-x86_64-O2/native-lisp/28.0.50-e2ae3598/hl-line-8fa29c14-664ef650.eln
>>
>> The middle hash (e67628ec vs. 8fa29c14) is not the same - any idea why ?

Also a following obsrvation from this:

a) Initially, the AOT bootstrap creates:
   <build-dir>/native-lisp/28.0.50-e2ae3598/hl-line-8fa29c14-664ef650.eln

b) Running <build-dir>/src/emacs complains about:
   <user-emacs-dir>/eln-cache/28.0.50-e2ae3598/hl-line-e67628ec-664ef650.eln

c) The running emacs then builds:
   ~/.emacs.d/eln-cache/28.0.50-e2ae3598/hl-line-8fa29c14-664ef650.eln

The files (a) and (c) have the same filename, but different sizes and
content.

    AndyM