Alexandre Oliva - Re: Updating top-level autoconf to 2.59 (original) (raw)

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On Feb 9, 2007, Ian Lance Taylor iant@google.com wrote:

I just routinely specify all of --build, --host, and --target. With autoconf's rules, I have to do an odd little dance to remove --host and/or --target in some cases. That dance is completely doable but it is not, I believe, intuitive.

With the alternate rules proposed upthread, you'd have just a different kind of odd little dance to specify the options to enable cross compilation. Which would be just as bad, possibly even worse.

The current scheme removes a lot of the ambiguity from earlier guessing with, I believe, the least hassle, even though it creates some inconvenience during the transition, until you get used to the new conventions.

In the end, the only way to avoid the guessing that led to incorrect results in the past is to get the user to supply the needed information, and the current rules accomplish that without inventing new options that would make room for inconsistencies, while still working seamlessly most of the time.

And in case one is really unhappy about the implied cross-compilation with host=build or cross-toolchain status when target=host, it's not too hard to work around that on a per-project basis. But then, does it really matter?

If we add options to say "build with native compiler/cross-compiler" and "build a native toolchain/cross-compiler" then it becomes much simpler to reason about what you want to happen.

I think this is just because you're looking at it from the perspective of someone already used to what was in place before. If you start with a clean slate, it becomes a problem of "what should I specify to accomplish what I want?". Do I want to name the platform I'm building on (--build), or let autoconf guess it? Do I want to build programs to run on a different platform (--host) or not? Do I want to build a cross toolchain (--target) or not? Can it possibly get simpler than this?

And note that adding such options is completely backward compatible. They would just override the way that autoconf makes assumptions.

We can do this in GCC, but I really don't think it's worth the hassle. Just consider the consequences of the change:

That's it. How bad can this be?

-- Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/ FSF Latin America Board Member http://www.fsfla.org/ Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org} Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}

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