Re: [Boost-cmake] Variant Builds and missing libraries

Subject: Re: [Boost-cmake] Variant Builds and missing libraries
From: Vladimir Prus (vladimir_at_[hidden])
Date: 2008-11-26 09:32:16

Michael Jackson wrote:

> 
> On Nov 13, 2008, at 12:31 PM, Vladimir Prus wrote:
> 
>> Michael Jackson wrote:
>>
>>>
>>> On Nov 12, 2008, at 11:39 AM, David Abrahams wrote:
>>>
>>>>
>>>> on Wed Nov 12 2008, Michael Jackson <mike.jackson-AT-bluequartz.net>
>>>> wrote:
>>>>
>>>>> Came across an interesting situation while doing some testing on
>>>>> the
>>>>> CMake build system. I configured my build tree to be SHARED+MULTI-
>>>>> THREADED+DEBUG. When I built I was almost immediately getting an
>>>>> error
>>>>> about not being able to link against boost_test_exec_monitor-mt-
>>>>> shared. Which is wrong because test_exec_monitor is a static-only
>>>>> library. As I walked through the CMake code to track down what was
>>>>> the
>>>>> problem I basically discovered for myself that if you have
>>>>> BUILD_STATIC=OFF then NO static libraries will be built, which has
>>>>> the
>>>>> side effect of disabling any regression test that relies on the
>>>>> test_exec_monitor.
>>>>>
>>>>>  Question: Is this desired behavior? (I wouldn't think so but I
>>>>> would rather hear that from a boost dev)
>>>>
>>>> Well, you'd need a Boost-CMake dev, of which there are few, to tell
>>>> you
>>>> what BUILD_STATIC=OFF is supposed to mean.  However, my guess is
>>>> that
>>>> it's really for deciding which library variants you're going to
>>>> build
>>>> and install, not what can get built as part of a dependency chain.
>>>> Frankly, even in the build/install case, it seems implausible that
>>>> people could be unhappy when a static-only library is built
>>>> statically
>>>> when the shared variant is requested.  I would err on the side of
>>>> building rather than not building, and let people use --without-
>>>> libname
>>>> or whatever its CMake equivalent is if they want to leave it out.
>>>
>>> I chatted with Volodya on the #boost irc channel and basically if you
>>> are doing regression testing then all the variants are built.
>>
>> Err, I did not say that. I said that Boost.Build does not need any
>> up-front
>> build of anything -- if you want to run regressions with specific
>> properties,
>> it will build all that's needed.
>>
>> - Volodya
>>
>>
> 
> That was my basic interpretation. Basically, if you are building the
> regression tests then you will need all the variants because at some
> point all the variants are most likely used.

We seem to be miscommunicating on this point :-( Why 
"all the variants are most likely used"? If I'm running test with
variant=debug link=shared, then I don't need variant=release, ever.

> I can start putting logic into the cmake files to make sure the proper
> variants are built but it is just easier to build all of them if you
> are going to be running tests. I am interested to hear all the
> arguments either way.

You'll be just wasting disk space with 8 variants of libraries, where
only 1 is needed. And debug variants are huge.

- Volodya