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

[Andy Moreton]

On Fri 26 Feb 2021, Andrea Corallo via "Bug reports for GNU Emacs, the Swiss 
army knife of text editors" wrote:

> Andy Moreton <andrewjmoreton@gmail.com> writes:
>
> [...]
>
>> The problem is with the file names used to generate the hashes, where
>> comparison of file names.
>>
>> As an experiment, I changed epaths.h from:
>> #define PATH_DUMPLOADSEARCH "C:/emacs/git/emacs/native/lisp"
>>
>> to:
>> #define PATH_DUMPLOADSEARCH "c:/emacs/git/emacs/native/lisp"
>>
>> and then ran make (to build without regenerating the header).
>> The resulting emacs did not complain about mismatched filenames.
>>
>> Thus the fix outlined by Eli above looks like it will solve the problem.
>>
>>     AndyM
>
> Hi Andy,
>
> could you give it a try to the attached patch?  It follows Eli's
> suggestion of using 'Fw32_long_file_name'.

The patch looks good - please apply it.

I tried building with the patch applied to a clean tree, and the
resulting emacs runs without the filename mismatch messages, and did not
recompile the AOT files into the per-user eln-cache.

There were also a couple of errors in the build:

Backtrace:
00007ff78467a2a2
00007ff78453be26
00007ff7845a98ac
...[snipped]...
00007ff784626548
Eager macro-expansion failure: (file-error "Renaming" "Permission
denied"
"c:/emacs/git/emacs/native/build/mingw64-x86_64-O2-native/native-lisp/28.0.50-e09cfb99/cc-bytecomp-4817e810-d16f606e.eln"
"c:/emacs/git/emacs/native/build/mingw64-x86_64-O2-native/native-lisp/28.0.50-e09cfb99/cc-bytecomp-4817e810-d16f606e.elnGMMUdn.eln.tmp")
C:/emacs/git/emacs/native/src/alloc.c:3160: Emacs fatal error: assertion 
failed: cu->handle
make[2]: *** [Makefile:319: progmodes/antlr-mode.elc] Error 3

The backtrace addresses did not give anything useful from addr2line.

There are still some elisp files that did not get native compiled when
the build was done with "make -j8 NATIVE_FULL_AOT=1", and so get async
compiled when running the built emacs:

  ansi-color auth_source byte-opt bytecomp cconv cl-extra cl-lib cl-macs
  cl-seq comint comp comp-cstr cus-edit cus-start desktop
  display-fill-column-indicator easy-mmode easymenu edmacro eieio
  eieio-core frameset gv help-mode hl-line image-file info json kmacro
  map minibuf-eldef package paren password-cache pcase pp ring rx seq
  subr-x time-date warnings wid-edit

That may be a result of the error during the build.

    AndyM