Re: Compilation speed

[Arthur Miller <arthur.miller@live.com>]

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 8/10/20 7:33 AM, Arthur Miller wrote:
>
>> Since Emacs requires C99 compiler (as I understand) couldn't configure
>> script just check for avialability of C99 standard, OS and compiler and
>> assume the headers, flags and certain functions are avialable?
>
> Unfortunately not. Lots of implementations conform mostly to C99 but have some
> exceptions. So we can't have a single C99 test; we need individual tests to 
> cover the exceptions.
Ok, I understand; does it mean that different options are chosen per
compiler; or does configure bail out? I am sorry if I ask obvious/stupid
question, I am not so familiar with how autotools works under the hood, despite
executing that ./configure so many times :-).

Can't we say: you need a c99 conformant compiler, otherwise
compile will fail; and for those that use not fully conformant compiler,
let them be on their own? That is how lots of software nowdays work;
they will tell the requirements, and is up to end-user to meet those.

> That's not to say we couldn't prune 'configure'; we could. It has several tests
> that are no longer relevant on today's porting targets. The problem is finding 
> the developer time to prune them. There's a lot of good stuff there mixed in
> with the cruft.

Yes, and trick is to know which are safe to remove.

>> Couldn't autotools devs, make those tests run in their
>> own shell as asynchronous processes, write output to a file and then
>> make a finall pass over all outputs and then decide to bail out/continue
>> or take an action.
>
> Yes, but this would require quite a rewrite, as existing scripts typically don't
> say which tests depend on which other tests' results. I'm not saying it couldn't 
> be done, only that it wouldn't be that easy.

Yes, I understand that :-). Would require new/modern autotools
implementation written for a parallel computer.