This is both a short form of using a TARGET_DEFINED expression
together with a TARGET_PROPERTY definition, and a way to strip
non-target content from interface properties when exporting.
This new expression allows checking how a policy was set when a target
was created. That information is only recorded for a subset of policies,
so a whitelist is used.
This is for specifying INCLUDE_DIRECTORIES relevant to the build-location
or the install location for example:
set_property(TARGET foo PROPERTY
INTERFACE_INCLUDE_DIRECTORIES
"$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR};${CMAKE_CURRENT_SOURCE_DIR}>"
"$<INSTALL_INTERFACE:${CMAKE_INSTALL_PREFIX}/include>"
)
A 'bar' target can then use:
set_property(TARGET bar PROPERTY
INCLUDE_DIRECTORIES
"$<TARGET_PROPERTY:foo,INTERFACE_INCLUDE_DIRECTORIES>"
)
and it will work whether foo is in the same project, or an imported target
from an installation location, or an imported target from a build location
generated by the export() command.
Because the generator expressions are only evaluated at build-time, these
new expressions are equivalent to the ZeroNode and OneNode.
The GeneratorExpression test is split into parts. Some shells can't run
the custom command as it is getting too long.
There are two overloads, so that it can use the operational
target when a target property is being evaluated, and a target
can alternatively be specified by name.
At this point, the generators don't chain. That comes later.
Generator expressions for comparing strings, evaluating
strings as booleans, and for creating literal right-angle-brackets
and commas are added. Those may be needed in some cases
where they appear in literals.
This expression evaluates to '1' or '0' to indicate whether the build
configuration for which the expression is evaluated matches tha named
configuration. In combination with the "$<0:...>" and "$<1:...>"
expressions this allows per-configuration content to be generated.
Add generator expressions that combine and use boolean test results:
$<0:...> = empty string (ignores "...")
$<1:...> = content of "..."
$<AND:?[,?]...> = '1' if all '?' are '1', else '0'
$<OR:?[,?]...> = '0' if all '?' are '0', else '1'
$<NOT:?> = '0' if '?' is '1', else '1'
These will be useful to evaluate (future) boolean query expressions and
condition content on the results. Include tests and documentation.
Stephen Kelly
Rolf Eike Beer
Brad King