Minetest fails to link JSONCPP on Debian 9.x if -DENABLE_SYSTEM_JSONCPP=1

[Megaf]

Might be some problem on Debian itself, I tried with Minetest Stable 0.4 branch too and got the same result.
cmake /home/user/Documents/games/minetest -DWARN_ALL=0 -DRUN_IN_PLACE=0 -DENABLE_GETTEXT=0 -DENABLE_CURL=0 -DCMAKE_BUILD_TYPE=MinSizeRel -DENABLE_LEVELDB=0 -DENABLE_POSTGRESQL=0 -DENABLE_REDIS=0 -DENABLE_SPATIAL=0 -DENABLE_SYSTEM_GMP=1 -DENABLE_SYSTEM_JSONCPP=1 -DENABLE_CURSES=0 -DENABLE_GLES=1 -DRUN_IN_PLACE=1

[100%] Linking CXX executable /home/user/Documents/games/minetest/bin/minetest
CMakeFiles/minetest.dir/client/clientlauncher.cpp.o: In function `ClientLauncher::launch_game(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, bool, GameParams&, Settings const&)':
clientlauncher.cpp:(.text+0x1c6a): undefined reference to `Json::Value::operator=(Json::Value const&)'
clientlauncher.cpp:(.text+0x1ca9): undefined reference to `Json::Value::operator=(Json::Value const&)'
clientlauncher.cpp:(.text+0x1ce8): undefined reference to `Json::Value::operator=(Json::Value const&)'
clientlauncher.cpp:(.text+0x1d27): undefined reference to `Json::Value::operator=(Json::Value const&)'
CMakeFiles/minetest.dir/script/common/c_content.cpp.o: In function `read_json_value(lua_State*, Json::Value&, int, unsigned char)':
c_content.cpp:(.text+0x1c74): undefined reference to `Json::Value::operator=(Json::Value const&)'
CMakeFiles/minetest.dir/script/common/c_content.cpp.o:c_content.cpp:(.text+0x1ca6): more undefined references to `Json::Value::operator=(Json::Value const&)' follow
collect2: error: ld returned 1 exit status
src/CMakeFiles/minetest.dir/build.make:5330: recipe for target '/home/user/Documents/games/minetest/bin/minetest' failed
make[2]: *** [/home/user/Documents/games/minetest/bin/minetest] Error 1
CMakeFiles/Makefile2:142: recipe for target 'src/CMakeFiles/minetest.dir/all' failed
make[1]: *** [src/CMakeFiles/minetest.dir/all] Error 2
Makefile:149: recipe for target 'all' failed
make: *** [all] Error 2

Debian Stretch x86_64.

[Zeno-]

Well, it's certainly not caused by 4c530de because that commit only changes comments.

[Fixer-007]

GCC 4.9.2 cross-compilation was successful on that build.

[Megaf]

@Zeno- Stable 0.4 doesnt link either, maybe a problem with Debian itself?

[Rogier-5]

From superficial examination, I guess that minetest may be using the wrong header files, or linking against the incorrect jsoncpp library. See also this information and this issue. Most people probably don't use -DENABLE_SYSTEM_JSONCPP=1, so that might be the reason that the problem has remained undetected.

If that is the problem, maybe that removing src/json might make a difference (workaround-type).

[Megaf]

@Rogier-5 Indeed it links with -DENABLE_SYSTEM_JSONCPP=0

[Rogier-5]

Indeed it links with -DENABLE_SYSTEM_JSONCPP=0

Then, from the information, it seems that minetest either still uses the included version of the json include file (instead of the system version) when compiling with -DENABLE_SYSTEM_JSONCPP=1, or it uses the correct include file, but links with the included version of the json library anyway, instead of using the system version.

[Rogier-5]

The primary problem turns out to be that minetest uses #include "json/json.h", where it should use #include <json/json.h>. I fixed that - see PR #4429

[Megaf]

@sfan5 Why you closed this if it wasnt fixed?

[sfan5]

The PR that was supposed to fix this was merged.

[paramat]

Similar problem reported by rdococ and others have recently mentioned problems with JSON.

[rdococ]

For me, using Debian 8.6, neither -DENABLE_SYSTEM_JSONCPP=1 nor -DENABLE_SYSTEM_JSONCPP=0 seems to work.

[stujones11]

Solution for me here: https://forum.minetest.net/viewtopic.php?f=6&t=18147

Not sure if this is debian or MT related so did not open an issue.

[Megaf]

Fixed.

[ne-vlezay80]

[ 35%] Building CXX object src/CMakeFiles/minetest.dir/script/scripting_client.cpp.o
/usr/src/minetest/src/script/lua_api/l_util.cpp: In static member function ‘static int ModApiUtil::l_parse_json(lua_State*)’:
/usr/src/minetest/src/script/lua_api/l_util.cpp:101:3: error: ‘CharReaderBuilder’ is not a member of ‘Json’
   Json::CharReaderBuilder builder;
   ^
/usr/src/minetest/src/script/lua_api/l_util.cpp:102:3: error: ‘builder’ was not declared in this scope
   builder.settings_["collectComments"] = false;
   ^
/usr/src/minetest/src/script/lua_api/l_util.cpp:105:8: error: ‘parseFromStream’ is not a member of ‘Json’
   if (!Json::parseFromStream(builder, stream, &root, &errs)) {
        ^
[ 35%] Building CXX object src/CMakeFiles/minetest.dir/script/scripting_mainmenu.cpp.o
src/CMakeFiles/minetest.dir/build.make:1434: ошибка выполнения рецепта для цели «src/CMakeFiles/minetest.dir/script/lua_api/l_util.cpp.o»
make[2]: *** [src/CMakeFiles/minetest.dir/script/lua_api/l_util.cpp.o] Ошибка 1
make[2]: *** Ожидание завершения заданий…
CMakeFiles/Makefile2:193: ошибка выполнения рецепта для цели «src/CMakeFiles/minetest.dir/all»
make[1]: *** [src/CMakeFiles/minetest.dir/all] Ошибка 2
Makefile:137: ошибка выполнения рецепта для цели «all»
make: *** [all] Ошибка 2

EDIT by SmallJoker: Added code block around to display it correctly

[Megaf]

Not sure if that is related to this issue.

[Megaf]

I just built Minetest Server 0.4 stable on Debian Buster/Testing/10. With systemjson, no problem at all. @ne-vlezay80 @SmallJoker