weird byte compile message when using (when t ... )

weird byte compile message when using (when t ... )

[Emanuel Berg via Users list for the GNU Emacs text editor]

When I enclose .emacs [1] in (when t ... ) or
(if t (progn ... )) the following what I can see (?) incorrect
warnings are reported

  In toplevel form:
  ~/.emacs:169:7: Warning: assignment to free variable ‘show-paren-delay’

  In end of data:
  ~/.emacs:223:1: Warning: the following functions are not known to be defined:
      enable-line-mode, conf-space-mode-hook-f, text-mode-hook-f

When I remove the enclosure and compile everything again no
errors or warnings are reported.

[1] https://dataswamp.org/~incal/conf/.emacs

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http://user.it.uu.se/~embe8573
https://dataswamp.org/~incal

Re: weird byte compile message when using (when t ... )

[Stefan Monnier]

> When I enclose .emacs [1] in (when t ... ) or
> (if t (progn ... )) the following what I can see (?) incorrect
> warnings are reported

The byte-compiler treats code differently if it's a "toplevel" or not
(where "toplevel" either literally means "not nested inside anything
else" or "nested inside a `progn` (or something that expands to one)
that is a toplevel").

E.g. of things this affect:
- a function definition that's not at toplevel will not be considered
  as defined when compiling the current file.
- a `require` that's not at toplevel will not be executed during compile time.
- a `defmacro` that's not at toplevel will not be available for
  expansion of macros within the same file.
- ...

So that can make big differences to warnings (and more).  This can be
used on purpose, of course, such as using `(if t (require 'foo))` to
make sure `foo` is only required when the file is loaded, so that
compilation of the file will not fail just because `foo` is missing.


        Stefan

Re: weird byte compile message when using (when t ... )

[Emanuel Berg via Users list for the GNU Emacs text editor]

Stefan Monnier wrote:

> The byte-compiler treats code differently if it's
> a "toplevel" or not (where "toplevel" either literally means
> "not nested inside anything else" or "nested inside
> a `progn` (or something that expands to one) that is
> a toplevel").

OK, king, thanks :)

-- 
underground experts united
http://user.it.uu.se/~embe8573
https://dataswamp.org/~incal