What happens if you put the genex inside double quotes?
target_link_libraries(my_exe PUBLIC "$<$<BOOL:${USE_FOOLIB}>:${FOO_LIBRARIES}>" "$<$<BOOL:${USE_BARLIB}>:bar>" ) ________________________________ From: CMake <cmake-boun...@cmake.org> on behalf of Björn Blissing <bjorn.bliss...@vti.se> Sent: October 4, 2018 8:49:19 AM To: Eric Noulard Cc: CMake Mailinglist Subject: Re: [CMake] Trouble with conditional generator expression inside target_link_libraries Hi Eric, I tried to do a self contained minimal example: cmake_minimum_required(VERSION 3.12) project(expension_error LANGUAGES CXX) add_executable(my_exe main.cpp) option(USE_FOOLIB "Use foo.lib" ON) option(USE_BARLIB "Use bar.lib" ON) list(APPEND FOO_LIBRARIES optimized foo) list(APPEND FOO_LIBRARIES debug foo_d) target_link_libraries(my_exe PUBLIC $<$<BOOL:${USE_FOOLIB}>:${FOO_LIBRARIES}> $<$<BOOL:${USE_BARLIB}>:bar> ) But when I run this script using CMake 3.12.2, it expands to something even worse: $<1:optimized;foo.lib;foo_d>.lib;bar.lib --- for debug builds $<1:optimized;foo.lib;>.lib;bar.lib-- for release builds So something goes really wrong when I try to use a list inside a conditional generator expression inside target_link_libraries(). Regards, Björn From: Eric Noulard <eric.noul...@gmail.com> Sent: Thursday, October 4, 2018 5:10 PM To: Björn Blissing <bjorn.bliss...@vti.se> Cc: CMake Mailinglist <cmake@cmake.org> Subject: Re: [CMake] Trouble with conditional generator expression inside target_link_libraries Le jeu. 4 oct. 2018 à 16:53, Björn Blissing <bjorn.bliss...@vti.se<mailto:bjorn.bliss...@vti.se>> a écrit : Hello Eric, The minimal example was just to display the expansion error. In real life the code uses a Boolean variable (and the rest of the CMake code is much larger as well). It was just to show the expansion error you get if you try to use a conditional generator expression inside a target_link_libraries function. Sometimes the devil is hiding in the details. Do ou manage to reproduce the genex expansion error on a toy example? I do agree that using it would be simpler if I could use: $<$<CONFIG:Debug>:${MYLIBS_DEBUG}> $<$<CONFIG:Release>:${MYLIBS_OPTIMIZED}> But since I use a third party find module the MYLIB_LIBRARIES variable is not separated into these categories. I was hoping to avoid rewriting this external find module. You can perfectly write a CMake helper function which takes MYLIB_LIBRARIES as input and spit out MYLIBS_DEBUG, MYLIBS_OPTIMIZED as an output. This way you don't have to rewrite 3rd party code and keep your code clean. -- Eric
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