Re: [PATCH v2 01/10] capstone: Convert Makefile bits to meson bits

[Paolo Bonzini]

On 15/09/20 16:27, Richard Henderson wrote:
> On 9/14/20 11:27 PM, Paolo Bonzini wrote:
>> Looks good. Can you just add a "# Submodules" heading above the test?
>>
>> I would also like to remove the "yes" value (that is, the default fails if 
>> the
>> internal copy is not there) but it can be done later for all submodules.
> 
> Unless you simply plan to rename {no, yes} to {disabled, enabled}, as for the
> Feature objects, why?
> 
> That seems to be the only sensible value for --enable-foo, without the =system
> or =git specifiers.  We *should* fail if no system library nor internal copy 
> is
> present.

Yes, that was a bit concise.  I would like "auto" to take the meaning
that "yes" currently as.  Right now we have

no -> Easy :)
system -> System capstone if found, fail otherwise
internal/git -> Compile capstone if found, fail otherwise
auto -> System capstone, then internal, then disable
yes -> System capstone, then internal, then fail

I'm not sure of the usefulness of disabling a dependency because we
don't have it checked out, since we have the machinery to do the
checkout automatically.  So that would become:

no -> Easy :)
system -> System capstone if found, fail otherwise
internal/git -> Compile capstone if found, fail otherwise
auto -> System capstone, then internal, then fail

The disadvantage is that it would be different from other "auto"
symbols, which never fail.  But then those other "auto" symbols do not
have a built-in fallback, so the question is whether the combination of

1) building from a fresh git checkout
2) --disable-git-update
3) not having a system capstone/libfdt/slirp
4) not having --disable-{capstone,libfdt,slirp} on the command line

is more likely to be intentional or operator error.

Paolo