map_server 1.14.1 and 1.15.0 are failing to export pthread correctly and is breaking downstream packages

[tfoote]

There are 3 regressions with the same issue:
http://build.ros.org/job/Kbin_uX64__turtlebot3_navigation__ubuntu_xenial_amd64__binary/
http://build.ros.org/job/Kbin_uX64__stdr_server__ubuntu_xenial_amd64__binary/
http://build.ros.org/job/Kbin_uX64__multi_map_server__ubuntu_xenial_amd64__binary/

Example failure:
http://build.ros.org/view/Kbin_uX64/job/Kbin_uX64__multi_map_server__ubuntu_xenial_amd64__binary/33/console

00:00:52.988 -- Looking for pthread.h
00:00:53.079 -- Looking for pthread.h - found
00:00:53.082 -- Looking for pthread_create
00:00:53.150 -- Looking for pthread_create - not found
00:00:53.151 -- Looking for pthread_create in pthreads
00:00:53.230 -- Looking for pthread_create in pthreads - not found
00:00:53.231 -- Looking for pthread_create in pthread
00:00:53.321 -- Looking for pthread_create in pthread - found
00:00:53.324 -- Found Threads: TRUE  
00:00:53.325 -- Found gtest sources under '/usr/src/gtest': gtests will be built
00:00:53.327 -- Using Python nosetests: /usr/bin/nosetests-2.7
00:00:53.400 -- catkin 0.7.6
00:00:53.575 CMake Error at /opt/ros/kinetic/share/map_server/cmake/map_serverConfig.cmake:141 (message):
00:00:53.575   Project 'multi_map_server' tried to find library '-lpthread'.  The library
00:00:53.575   is neither a target nor built/installed properly.  Did you compile project
00:00:53.575   'map_server'? Did you find_package() it before the subdirectory containing
00:00:53.575   its code is included?
00:00:53.575 Call Stack (most recent call first):
00:00:53.575   /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:76 (find_package)
00:00:53.575   CMakeLists.txt:4 (find_package)
00:00:53.575 
00:00:53.575 
00:00:53.577 -- Configuring incomplete, errors occurred!
00:00:53.577 See also "/tmp/binarydeb/ros-kinetic-multi-map-server-2.2.2/obj-x86_64-linux-gnu/CMakeFiles/CMakeOutput.log".
00:00:53.577 See also "/tmp/binarydeb/ros-kinetic-multi-map-server-2.2.2/obj-x86_64-linux-gnu/CMakeFiles/CMakeError.log".
00:00:53.581 	cd /tmp/binarydeb/ros-kinetic-multi-map-server-2.2.2
00:00:53.581 	cd obj-x86_64-linux-gnu
00:00:53.581 	"tail -v -n +0 CMakeCache.txt"

[mikeferguson]

@tfoote -- I never got any build failure emails for this, but I am listed as a maintainer. Thoughts?

[mikeferguson]

Oh, never mind, I see, we broke downstream things

[mikeferguson]

I'm guessing this affects lunar as well, but none of the "busted" downstream things are released there yet

[mikeferguson]

@tfoote -- how did you determine it was pthread related?

[tfoote]

The errors in all the failing builds at the core are: Project 'multi_map_server' tried to find library '-lpthread'.

Digging a little deeper now and looking inside the generated package config file map_server.pc (from the testing deb) I see the following:

prefix=/opt/ros/kinetic

Name: map_server
Description: Description of map_server
Version: 1.14.1
Cflags: -I/opt/ros/kinetic/include -I/usr/include/SDL
Libs: -L/opt/ros/kinetic/lib -lmap_server_image_loader /usr/lib/x86_64-linux-gnu/libSDLmain.a -l:/usr/lib/x86_64-linux-gnu/libSDL.so -l-lpthread -l:/usr/lib/x86_64-linux-gnu/libSDL_image.so
Requires: roscpp nav_msgs tf2

Where I've confirmed the pthread export is corrupted.

[tfoote]

I've confirmed the same issue is in lunar. FYI @mikaelarguedas

The map_serverConfig.cmake generated into the debians has this line that I think is the same issue.
set(libraries "map_server_image_loader;/usr/lib/x86_64-linux-gnu/libSDLmain.a;/usr/lib/x86_64-linux-gnu/libSDL.so;-lpthread;/usr/lib/x86_64-linux-gnu/libSDL_image.so")

[mikeferguson]

@wjwwood -- I think this is related to #560, since that is the only thing adding new libraries. Do you have any idea how we can fix it?

[k-okada]

This is very interesting and now I understand why our multi_map_server failes to build
#find_package(SDL REQUIRED)
https://github.com/ros-planning/navigation/blob/kinetic-devel/map_server/CMakeLists.txt#L12
provides
SDL_LIBRARY = /usr/lib/x86_64-linux-gnu/libSDLmain.a;/usr/lib/x86_64-linux-gnu/libSDL.so;-lpthread

This was set by
https://gitlab.kitware.com/cmake/cmake/blob/master/Modules/FindSDL.cmake#L164 as
set(SDL_LIBRARY_TEMP ${SDL_LIBRARY_TEMP} ${CMAKE_THREAD_LIBS_INIT})

and CMAKE_THREAD_LIBS_INIT is set to -lpthread by find_package(Threads) https://cmake.org/cmake/help/v3.0/module/FindThreads.html

So I am not sure what is the better way to fix that. May be FindThrads.cmake set -lpthread is ok, but we could not find any issue report on cmake.
https://gitlab.kitware.com/cmake/cmake/issues?scope=all&utf8=%E2%9C%93&state=all&search=FindSDL

One workaround map_server level is to remove find_package(SDL REQUIRED), this might affect some downstream packages. Or more dirty fix is something like

list(FIND SDL_LIBRARY "-lpthread" _PTHREAD_INDEX)
if(${_PTHREAD_INDEX} GREATER -1)
  list(INSERT SDL_LIBRARY ${_PTHREAD_INDEX} "pthread")
  MATH(EXPR _PTHREAD_INDEX "${_PTHREAD_INDEX} + 1")
  list(REMOVE_AT SDL_LIBRARY ${_PTHREAD_INDEX})
endif()

[wjwwood]

I came to the same conclusion as @k-okada, I think the offending flag is coming from SDL, and I'm not sure what we're supposed to do about that. I suppose we could try removing the flag as @k-okada suggested.

[mikeferguson]

Doesn't even look like those downstream packages are building anything against our library -- I'm going to revert the SDL additions for now, so we can get this released.

[mikeferguson]

New releases:

• navigation: 1.15.1-0 in 'lunar/distribution.yaml' [bloom] ros/rosdistro#15777
• navigation: 1.14.2-0 in 'kinetic/distribution.yaml' [bloom] ros/rosdistro#15778

[AmeyHande]

Hello guys,
I'm also facing same error.
I have latest version of map_server package installed from ros repository for Melodic version.
Any guidance?