bug#14551: compiler fails to track eval-when-compile in required files

bug#14551: compiler fails to track eval-when-compile in required files

[Glenn Morris]

Package: emacs
Severity: minor
Version: 24.3

(I guess this issue has always been present.)

Suppose we have three files:


foo.el:
(require 'lib)
(defun foo ()
  (lib2-func))


lib.el:
(eval-when-compile
  (require 'lib2))
(provide 'lib)


lib2.el:
(defun lib2-func ()
  t)
(provide 'lib2)


rm lib*.elc
emacs -Q -L . -batch -f batch-byte-compile foo.el

produces no warnings.

If lib.el is compiled first though:
emacs -Q -L . -batch -f batch-byte-compile lib.el
emacs -Q -L . -batch -f batch-byte-compile foo.el

In end of data:
foo.el:6:1:Warning: the function `lib2-func' is not known to be defined.


eval-when-compile is equivalent to progn in uncompiled code, and the
compiler doesn't compile things brought in by require.

bug#14551: compiler fails to track eval-when-compile in required files

[Stefan Monnier]

> foo.el:
> (require 'lib)
> (defun foo ()
>   (lib2-func))
[...]
> lib.el:
> (eval-when-compile
>   (require 'lib2))
> (provide 'lib)
[...]
> rm lib*.elc
> emacs -Q -L . -batch -f batch-byte-compile foo.el
> produces no warnings.

Yes, that's a long standing bug.  Fixing it right is likely to be pretty
tricky/difficult because it means we need to disregard some of the
packages already loaded somehow.  In the general case, you have the same
problem even without eval-when-compile, e.g. if you have in lib.el
a call to an autoloaded macro, in which case the autoloaded package will
be loaded if lib.el is not yet compiled but not if it is.

The "noruntime" warnings are implemented with a pile of hacks, and I'd
rather not add to them.  So, given that a proper fix looks pretty
difficult, I wouldn't hold my breath.


        Stefan

bug#14551: compiler fails to track eval-when-compile in required files

[Stefan Kangas]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> foo.el:
>> (require 'lib)
>> (defun foo ()
>>   (lib2-func))
> [...]
>> lib.el:
>> (eval-when-compile
>>   (require 'lib2))
>> (provide 'lib)
> [...]
>> rm lib*.elc
>> emacs -Q -L . -batch -f batch-byte-compile foo.el
>> produces no warnings.
>
> Yes, that's a long standing bug.  Fixing it right is likely to be pretty
> tricky/difficult because it means we need to disregard some of the
> packages already loaded somehow.  In the general case, you have the same
> problem even without eval-when-compile, e.g. if you have in lib.el
> a call to an autoloaded macro, in which case the autoloaded package will
> be loaded if lib.el is not yet compiled but not if it is.
>
> The "noruntime" warnings are implemented with a pile of hacks, and I'd
> rather not add to them.  So, given that a proper fix looks pretty
> difficult, I wouldn't hold my breath.

Is still an issue 10 years later?

bug#14551: compiler fails to track eval-when-compile in required files

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

> Is still an issue 10 years later?

I don't think anything has changed in this respect.


        Stefan