Re: [B2] Propagate CXX requirements to consumers

From: Alexander Grund (alexander.grund_at_[hidden])
Date: 2020-05-18 08:43:30

>> As another note on that: I have a test to be run on windows only by 
>> using:
>> <build>no <target-os>windows:<build>yes
>>
>> This now also breaks BJam as it sees a <build>no by the C++11 
>> requirements and a <build>yes by the above :(
>> No idea how to solve that.
>
> You could write a local rule that determines when to build the test. 
> You can see an example here:
>
> https://github.com/boostorg/filesystem/blob/92522691601533a2afdec9bdecb976741d614fdc/test/Jamfile.v2#L29 
>
> https://github.com/boostorg/filesystem/blob/92522691601533a2afdec9bdecb976741d614fdc/test/Jamfile.v2#L81 
>

This will get ugly here. I have 1 test which must only be build on 
Windows. ALL tests must only be build in C++11.

Hence I would need to decorate _every_ test with the C++11 requirement 
but that 1 test where I need to define a function that checks for the 
C++11 requirement _and_ if it is on Windows.

I guess this could be solved if B2 allows negation. So I can say: 
`<target-os>not windows:<build>no `.
Does this exist?