# Copyright 2017 Rene Rivera
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE.txt or copy at
# https://www.bfgroup.xyz/b2/LICENSE.txt)

# The following features are incidental since they have no effect on built
# products. Not making them incidental will result in problems in corner cases,
# e.g.:
#
#    unit-test a : a.cpp : <use>b ;
#    lib b : a.cpp b ;
#
# Here, if <use> is not incidental, we would decide we have two targets for
# a.obj with different properties and complain about it.
#
# Note that making a feature incidental does not mean it is ignored. It may be
# ignored when creating a virtual target, but the rest of build process will use
# them.

import feature ;

#| tag::doc[]

[[bbv2.builtin.features.dependency]]`dependency`::
Introduces a dependency on the target named by the value of this feature (so it
will be brought up-to-date whenever the target being declared is). The
dependency is not used in any other way.

|# # end::doc[]

feature.feature dependency
    :
    : free dependency incidental ;

#| tag::impl-doc[]

[[bbv2.builtin.features.implicit-dependency]]`implicit-dependency`::
Indicates that the target named by the value of this feature may produce files
that are included by the sources of the target being declared. See the section
<<Generated headers>> for more information.

|# # end::impl-doc[]

feature.feature implicit-dependency
    :
    : free dependency incidental ;

#| tag::use-doc[]

[[bbv2.builtin.features.use]]`use`::
Introduces a dependency on the target named by the value of this feature (so it
will be brought up-to-date whenever the target being declared is), and adds its
usage requirements to the build properties of the target being declared. The
dependency is not used in any other way. The primary use case is when you want
the usage requirements (such as `#include` paths) of some library to be
applied, but do not want to link to it.

|# # end::use-doc[]

feature.feature use
    :
    : free dependency incidental ;