Re: [Qemu-devel] [PATCH] configure: disallow ccache during compile tests

[Markus Armbruster]

John Snow <address@hidden> writes:

> On 10/29/2015 02:17 AM, Markus Armbruster wrote:
>> John Snow <address@hidden> writes:
>> 
>>> If the user is using CCACHE during the configuration step,
>>> it may interfere with some of the configuration tests,
>>> particularly the "Is CCACHE interfering with macro analysis" step,
>>> which is a bit of a poetic problem.
>>>
>>> 1) Disallow CCACHE from reading from the cache during configure,
>>>    but don't disable it to allow us to see if it causes other problems.
>> 
>> This is confusing.  "don't disable it entirely"?
>> 
>
> We allow it to submit items into the cache, but not to read items from
> the cache. This prevents it from picking up cached results to the
> compile tests.
>
> I don't disable it entirely (just pass-through to the real compiler
> without using ccache at all) because I still want to allow ccache to be
> processing things to test for ccache failures -- particularly the ccache
> macro check that occurs later.
>
> If I just disable ccache, that later check is meaningless. Setting the
> cache to "write only" gives me the best of both worlds.

All right, shows that I can confuse with the best of them!

It took my a moment to understand what "disallow but don't disable"
means.  I think inserting "entirely" into your sentence right after
"disable it" makes it easier to understand.

>>> 2) Force off CCACHE_CPP2 during the ccache test to get a deterministic
>>>    answer over whether or not we need to enable that feature later.
>>>
>>> Signed-off-by: John Snow <address@hidden>