In a certain tool I'm having a situation where I need to install a package while byte-compiling a file. Since installing a package also involves byte-compilation, it results in byte-compilation invoked when inside another byte-compilation. It seems to work _mostly_ fine, but still there are quirks.
Here is a short program that I created to emulate this scenario:
(eval-when-compile
(let ((default-directory (expand-file-name "/tmp/myprivatelib/")))
(make-directory default-directory t)
(with-temp-file "thelib.el"
(insert "(defun im-a-library-function ()\n"
" (trigger-a-warning-here-1))\n"
"(provide 'thelib)\n"))
(byte-compile-file "thelib.el")))
(defun blabla ()
(trigger-a-warning-here-2))
To test, run from the command line (having saved it as `main.el'):
$ emacs --batch --eval "(print (byte-compile-file \"main.el\"))"
The "program" is deliberately written to issue byte-compilation warnings. First quirk is that the path for outer file (i.e. `main.el') is written fully, because it is apparently found from `/tmp/myprivatelib':
In end of data:
thelib.el:4:1: Warning: the function ‘trigger-a-warning-here-1’ is not known
to be defined.
In end of data:
~/test/nested-compilation/main.el:12:1: Warning: the function
‘trigger-a-warning-here-2’ is not known to be defined.
t
If, for a test, you remove the `(byte-compile-file "thelib.el")' form, file path becomes just `main.el', as expected. In other words, *presence of inner byte-compilation can affect output of outer*, which doesn't look correct to me.
Another, more important problem is that the outer byte-compilation will fail if inner one fails (just e.g. remove a paren from "(provide 'thelib)\n" string):
In toplevel form:
thelib.el:3:1: Error: End of file during parsing
In end of data:
~/test/nested-compilation/main.el:12:1: Warning: the function
‘trigger-a-warning-here-2’ is not known to be defined.
nil
It feels wrong, because byte-compilation of `main.el' itself _was successful_. What did fail was a different and only tangentially related byte-compilation of `thelib.el'.
Is there a way to completely "insulate" the outer invocation of `byte-compile-...' from the inner? I.e. maybe my simple program above (and the real tool) can be just expanded to avoid such problems, while keeping recursive byte-compilation behavior?
If no, would Emacs be interested in resolving such an issue or would it be deemed too special and unimportant?
Paul