Question about eval and compile-command

[Eshel Yaron <me@eshelyaron.com>]

Hi all,

I'm curious as to why `compile` and `recompile` use `eval` to evaluate
the value of `compile-command`.  AFAICT since commit
5b6858da26e4e6671ee93b67b921a86309b3d6a2 (July 19 2001), these commands
evaluate `compile-command`, as if it's expected to be an expression that
evaluates to a string rather than just a plain string.

The commit message says:

    (compilation-parse-errors): `linenum' might return a this-error using
    the alternative format (a pair of markers).

But I don't quite understand how that relates to `compile-command`.

Also, the `:type` of `compile-command` remains `string`, and I couldn't
find any mention of the value of `compile-command` being evaluated that
way in the relevant documentation.

I wonder if this is just a remnant of a past experiment or an
undocumented feature.  Or maybe there's something else I'm missing?

Thanks,

Eshel