Merge lp:~widelands-dev/widelands/GLVND_18_10 into lp:widelands

[Toni Förster]

set CMP0072 to OLD for Ubuntu 18.10 when using GCC

Since it is only possible to compile with GLVND when using Clang on Ubuntu 18.10 we set CMP0072 to OLD behavior

[bunnybot (widelandsofficial)]

Continuous integration builds have changed state:

Travis build 4141. State: passed. Details: https://travis-ci.org/widelands/widelands/builds/441954041.
Appveyor build 3938. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_widelands_dev_widelands_GLVND_18_10-3938.

[kaputtnik (franku)]

Thanks for your hard work on this :-)

Have you tried the CMake variable CMAKE_SYSTEM or CMAKE_SYTEM_VERSION? From what i have read something like this should work also, without the need the call to lsb_release:

if (CMAKE_SYSTEM_VERSION MATCHES "Ubuntu 18.10")
 [...]

CMAKE_SYSTEM_VERSION should be the same as calling uname -r.

https://cmake.org/cmake/help/v3.0/manual/cmake-variables.7.html#variables-that-describe-the-system
https://cmake.org/cmake/help/v3.0/command/if.html

Compiling this branch now.

[GunChleoc (gunchleoc)]

Now I know why one of your forum members has "Cmake is evil" in his signature...

LGTM, let's merge and see what the daily PPA will say.

@bunnybot merge

[kaputtnik (franku)]

Compiles here :-)

=== modified file 'CMakeLists.txt'
--- CMakeLists.txt	2018-10-14 20:56:48 +0000
+++ CMakeLists.txt	2018-10-16 00:43:49 +0000
@@ -3,7 +3,7 @@
 cmake_minimum_required (VERSION 2.8.7)
 cmake_policy(VERSION 2.8.7)
 
-# This policy is not known to versions prior 3.1 and would result in errors, 
+# This policy is not known to versions prior 3.1 and would result in errors,
 # if set on such systems. This can be removed when cmake_minimum_required is set
 # to 3.1 or newer by using:
 # cmake_policy(VERSION 3.1)
@@ -11,12 +11,36 @@
    cmake_policy(SET CMP0054 NEW)
 endif(POLICY CMP0054)
 
-# This policy is not known to versions prior 3.11 and would result in errors, 
+# This policy is not known to versions prior 3.11 and would result in errors,
 # if set on such systems. This can be removed when cmake_minimum_required is set
 # to 3.11 or newer  by using:
 # cmake_policy(VERSION 3.11)
 if(POLICY CMP0072)
    cmake_policy(SET CMP0072 NEW)
+
+   # On Ubuntu 18.10 we need to set this policy to OLD when GCC is used.
+   #
+   #TODO(stonerl): Check on later Ubuntu releases whether workaround this is
+   # still needed or not.
+   if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+       find_program(LSB_RELEASE_EXEC lsb_release)
+       execute_process(COMMAND ${LSB_RELEASE_EXEC} -is
+           OUTPUT_VARIABLE LSB_RELEASE_ID_SHORT
+           OUTPUT_STRIP_TRAILING_WHITESPACE
+       )
+       execute_process(COMMAND ${LSB_RELEASE_EXEC} -cs
+           OUTPUT_VARIABLE RELEASE_CODENAME
+           OUTPUT_STRIP_TRAILING_WHITESPACE
+       )
+   endif()
+
+   if (LSB_RELEASE_ID_SHORT STREQUAL "Ubuntu" AND
+       RELEASE_CODENAME STREQUAL "cosmic" AND
+       CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
+   )
+       cmake_policy(SET CMP0072 OLD)
+   endif()
+
 endif(POLICY CMP0072)
 
 include("${CMAKE_SOURCE_DIR}/cmake/WlFunctions.cmake")