kumquat-buildroot/support/misc/toolchainfile.cmake.in
Yann E. MORIN c69b14fe2f core/pkg-cmake: provide our own platform description
The handling of RPATH in cmake-3.7 has changed drastically, causing a
slew of build failures dues to libraries from the host being pulled in:

  - domoticz : http://autobuild.buildroot.org/results/fd0/fd0ba54c7abf973691b39a0ca1bb4e07d749593a/
  - freerdp  : http://autobuild.buildroot.org/results/5d4/5d429d0e288754a541ee5d8be515454c5fccd28b/
  - libcec   : http://autobuild.buildroot.org/results/3f3/3f3593bab7734dd274faf5b5690895e9424cbb89/
  - and so on...

The bug was reported upstream [0], which dismissed it altogether [1] as
being expected behaviour, quoting:

    I don't think there is anything wrong with that change on its own.
    It merely exposed some existing behavior in a new case.

Instead, upstream suggested in that same message that a platform
definition be used instead, quoting:

    If a toolchain file specifies CMAKE_SYSTEM_NAME such that a custom
    `Platform/MySystem.cmake` file is loaded then the latter can set
    them as needed for the target platform.

So here we are doing so:

  - we add a new platfom definitions that inherits from the Linux one,
    then overrides the problematic settings;

  - we change our toolchain file to use that platform instead;

  - we tell cmake where to find additional modules, so that it can find
    our custom platform file.

This has been tested to work in the following conditions:

 - pre-installed host cmake, versions 3.5.1 (Ubuntu 16.04) and 3.7.2
   (manually built)

  - internal cmake, versions 3.6.3 (the current version as of this
    patch) and 3.7.2 (with the followup patches).

Thanks to Jörg, Ben and Baruch for the help investigating the issue.
Special thanks to Jörg for handling the discussion with upstream and
pointing to the relevant messages! :-)

[0] http://public.kitware.com/pipermail/cmake/2017-February/064970.html
[1] http://public.kitware.com/pipermail/cmake/2017-February/065063.html

To be noted: Thomas suggested we set these directly in the toolchain
file. Unfortunately, wherever we put those settings in the toolchain
file, this does not work.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Jörg Krause <joerg.krause@embedded.rocks>
Cc: Ben Boeckel <mathstuf@gmail.com>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Samuel Martin <s.martin49@gmail.com>
Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
2017-03-01 21:56:24 +01:00

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CMake

#
# Automatically generated file; DO NOT EDIT.
# CMake toolchain file for Buildroot
#
# In order to allow the toolchain to be relocated, we calculate the
# HOST_DIR based on this file's location: $(HOST_DIR)/usr/share/buildroot
# and store it in RELOCATED_HOST_DIR.
# All the other variables that need to refer to HOST_DIR will use the
# RELOCATED_HOST_DIR variable.
string(REPLACE "/usr/share/buildroot" "" RELOCATED_HOST_DIR ${CMAKE_CURRENT_LIST_DIR})
set(CMAKE_SYSTEM_NAME Buildroot)
set(CMAKE_SYSTEM_PROCESSOR @@CMAKE_SYSTEM_PROCESSOR@@)
# Set the {C,CXX}FLAGS appended by CMake depending on the build type
# defined by Buildroot. CMake defaults these variables with -g and/or
# -O options, and they are appended at the end of the argument list,
# so the Buildroot options are overridden. Therefore these variables
# have to be cleared, so that the options passed in CMAKE_C_FLAGS do
# apply.
#
# Note:
# if the project forces some of these flag variables, Buildroot is
# screwed up and there is nothing Buildroot can do about that :(
set(CMAKE_C_FLAGS_DEBUG "" CACHE STRING "Debug CFLAGS")
set(CMAKE_CXX_FLAGS_DEBUG "" CACHE STRING "Debug CXXFLAGS")
set(CMAKE_C_FLAGS_RELEASE " -DNDEBUG" CACHE STRING "Release CFLAGS")
set(CMAKE_CXX_FLAGS_RELEASE " -DNDEBUG" CACHE STRING "Release CXXFLAGS")
# Build type from the Buildroot configuration
set(CMAKE_BUILD_TYPE @@CMAKE_BUILD_TYPE@@ CACHE STRING "Buildroot build configuration")
# Buildroot defaults flags.
# If you are using this toolchainfile.cmake file outside of Buildroot and
# want to customize the compiler/linker flags, then:
# * set them all on the cmake command line, e.g.:
# cmake -DCMAKE_C_FLAGS="@@TARGET_CFLAGS@@ -Dsome_custom_flag" ...
# * and make sure the project's CMake code extends them like this if needed:
# set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Dsome_definitions")
set(CMAKE_C_FLAGS "@@TARGET_CFLAGS@@" CACHE STRING "Buildroot CFLAGS")
set(CMAKE_CXX_FLAGS "@@TARGET_CXXFLAGS@@" CACHE STRING "Buildroot CXXFLAGS")
set(CMAKE_EXE_LINKER_FLAGS "@@TARGET_LDFLAGS@@" CACHE STRING "Buildroot LDFLAGS for executables")
set(CMAKE_INSTALL_SO_NO_EXE 0)
set(CMAKE_PROGRAM_PATH "${RELOCATED_HOST_DIR}/usr/bin")
set(CMAKE_SYSROOT "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")
set(CMAKE_FIND_ROOT_PATH "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(ENV{PKG_CONFIG_SYSROOT_DIR} "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")
# This toolchain file can be used both inside and outside Buildroot.
set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC@@")
set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CXX@@")
if(@@TOOLCHAIN_HAS_FORTRAN@@)
set(CMAKE_Fortran_FLAGS_DEBUG "" CACHE STRING "Debug Fortran FLAGS")
set(CMAKE_Fortran_FLAGS_RELEASE " -DNDEBUG" CACHE STRING "Release Fortran FLAGS")
set(CMAKE_Fortran_FLAGS "@@TARGET_FCFLAGS@@" CACHE STRING "Buildroot FCFLAGS")
set(CMAKE_Fortran_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_FC@@")
endif()