On 10/31/2013 01:13 PM, Stephen Kelly wrote: > It is not obvious to the user that they are causing their downstreams to > depend on CMake 2.8.12. There was no warning about it (because there is no > bug in the code), no build error and no export error. > > By populating INTERFACE_LINK_LIBRARIES instead, the result would be that > downstreams require 2.8.12. If that's what you want I can change this when > the policy is NEW. I think that's fine. If they care about their > downstreams, they'd test or examine their export files when they bump their > cmake version requirement.
This is already the case when using the keyword signatures: cmake_minimum_required(VERSION 2.8.12) project(FOO C) add_library(foo SHARED foo.c) target_link_libraries(foo LINK_PUBLIC z) export(TARGETS foo FILE myTargets.cmake) No warning or error, and the export file only sets the new INTERFACE_LINK_LIBRARIES property. Once a project sets CMP0022 to NEW explicitly or by requiring 2.8.12 it is up to them to make it work as desired. We debated this extensively when first designing the policy and reached this conclusion. We just need to implement it correctly for the plain tll signatures like it already is for the keyword signatures. > Or maybe I can export both INTERFACE_LINK_LIBRARIES and > IMPORTED_LINK_INTERFACE_LIBRARIES. But then, when could we ever not export > IMPORTED_LINK_INTERFACE_LIBRARIES? That's why it's important to honor CMP0022==NEW and set the INTERFACE_LINK_LIBRARIES on export, and set the old properties only when explicitly requested by the new option. Prior to your proposed fix CMP0022==NEW would never export the old properties without EXPORT_LINK_INTERFACE_LIBRARIES. > Or we could make it a CMP0022-NEW-error to export a target which has link > dependencies and no explicit link interface and > EXPORT_LINK_INTERFACE_LIBRARIES is not used. That will produce an error in the basic use case of plain tll sig with export commands. As explained above we already have the silent bump in downstream requirement come from the bump in the upstream requirement. Also we can't introduce a new error case in a tweak release. The current error that suggests EXPORT_LINK_INTERFACE_LIBRARIES is when someone explicitly sets the old LINK_INTERFACE_LIBRARIES properties instead of using tll to do it. When all link info comes from tll we have enough information to know what to do. cmExportFileGenerator::SetImportLinkInterface should never set IMPORTED_LINK_INTERFACE_LIBRARIES when CMP0022 is NEW. Currently ImplementationIsInterface bypasses the policy check because it assumes the policy check was already done in cmTarget::ComputeLinkInterface before setting ImplementationIsInterface to true. I think what we need to do is when only the plain tll signature is used, cmTarget and cmExportFileGenerator logic should behave as if INTERFACE_LINK_LIBRARIES were always set to the link implementation and LINK_INTERFACE_LIBRARIES is set to the link implementation when CMP0022 is not NEW. -Brad -- Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://public.kitware.com/cgi-bin/mailman/listinfo/cmake-developers
