r231787 - Allow -target= and --target options

[Renato Golin]

On 11 March 2015 at 21:27, Chandler Carruth <chandlerc at google.com> wrote:
> We should have a single unambiguous spelling for long options in the absence
> of compatibility concerns with other tools.

+1

> The vastly more common prefix for these in the rest of the world is '--'.
> LLVM's usage of '-' is quite strange.

+1


> I also think there is a strong technical reason to require the '=' -- it
> makes the relative ordering unimportant. For any tool (such as a build
> system) which builds up commandline flags, this is a huge advantage.

+2!


> I don't know that we need some formal document of this kind, but if you'd
> like to propose a patch for the clang internals documentation, that would be
> nice.

The issue is that compatibility is a bit vague.

For instance, gcc has -mcpu=foo which is against the "agreed standard"
for optargs. Not that it's invalid, just that the Unix world kind of
agreed that the two accepted syntaxes are "-a opt" and "--a=opt" and
not the other two.

So, does "compatibility" means "only the ones that other tools have
specifically" (such as -mcpu), or "similar to what other tools have"
(such as -target)?

If the former, than I suggest we use the compatibility layer to
convert "legacy" options into standard ones. So, "--target=foo",
"--mcpu=bar" are the standard and "-target foo" and "-mcpu=bar" are
accepted as legacy options.

If the latter, than accepting all options for all choices is the only
way to keep everyone happy.

I vote for the first, but too many people seem to prefer the second.

cheers,
--renato