target_include_directories(... SYSTEM ...) does not work with cotire

[jcelerier]

Given this code:

cmake_minimum_required(VERSION 3.6)
project(foo)
set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}")

include(cotire)

add_library(foo a.cpp b.cpp c.cpp)
add_library(bar a.cpp b.cpp c.cpp)

target_include_directories(foo PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/3rdparty)
target_include_directories(bar SYSTEM PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/3rdparty)

set_property(TARGET foo PROPERTY COTIRE_CXX_PREFIX_HEADER_INIT "${CMAKE_CURRENT_SOURCE_DIR}/prefix.hpp")
set_property(TARGET bar PROPERTY COTIRE_CXX_PREFIX_HEADER_INIT "${CMAKE_CURRENT_SOURCE_DIR}/prefix.hpp")

cotire(foo)
cotire(bar)

foo can build, but bar cannot if the prefix header contains files that should be found through the include directories list.

[jcelerier]

test-genexp.zip

If you want to test. (It is called genexp because I thought that it was due to generator expressions at the beginning...)

[Quincunx271]

Looks like "${CMAKE_INCLUDE_SYSTEM_FLAG_${_language}} expands to "-isystem " (note the trailing space). Thus, the system include is passed as '-isystem include/dir', which seems to be ignored by the compiler. A possible solution is to remove the space:

// cotire.cmake:934, inside cotire_add_includes_to_cmd
        if (_index GREATER -1)
          string (STRIP "${CMAKE_INCLUDE_SYSTEM_FLAG_${_language}}" _systemIncludeFlag)
          list (APPEND ${_cmdVar} "${_systemIncludeFlag}${CMAKE_INCLUDE_FLAG_SEP_${_language}}${_include}")
        else()
          list (APPEND ${_cmdVar} "${CMAKE_INCLUDE_FLAG_${_language}}${CMAKE_INCLUDE_FLAG_SEP_${_language}}${_include}")
        endif()