Am 27.04.2018 um 15:13 schrieb Brad King:
On 04/26/2018 07:18 PM, Craig Scott wrote:
Perhaps it was an oversight that newer target_... commands don't have the same
restriction as target_link_libraries(), but it is a very useful oversight!
As the linked blog article explains, it allows much better modularity of the
project.
Yes, and usage requirements make non-local effects commonplace anyway.
Those didn't exist when the `target_link_libraries` restriction was
first put in place. Back then *everything* that affected a target's
build was in its own `CMakeLists.txt` file.
Being able to use add_subdirectory() instead of include() allows the
subdirectory
to be more isolated
The original restriction was to prevent parent and sibling directories from
affecting a target's build. We didn't think much about subdirectories as
a way of incrementally accumulating build information for a target.
I think it would be fine to lift the restriction if there is no technical
hurdle.
-Brad
As far as I can see, the code that prevents linking from other
directories starts here:
https://gitlab.kitware.com/cmake/cmake/blob/master/Source/cmTargetLinkLibrariesCommand.cxx#L369
The check for imported targets should be definitly kept since users
should still not be able to modify third party targets. Maybe
FindLocalNonAliasTarget() can be replaced with something like
FindNonAliasTarget() or FindGlobalNonAliasTarget() to catch aliases. I
am not sure whether such a thing already exists or must be implemented.
We can also continue the discussion at GitLab to avoid bothering the
others with such technical details if you like.
Best regards,
Patrick Stotko
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