Core/Build: Add the possibility to link libraries dynamically.

* makes it possible to access exported singletons from other shared lib's.
* reduces binary size

(cherry picked from commit f4e0945b13a70225684e7421d9542efae6a47c89)

8 files changed, 88 insertions, 6 deletions

diff --git a/.travis.yml b/.travis.yml
index 7ed50ef0ec4..894fedf4da6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,7 +21,7 @@ install:
   - mysql -uroot -e 'create database test_mysql;'
   - mkdir bin
   - cd bin
-  - cmake ../ -DWITH_WARNINGS=1 -DWITH_COREDEBUG=0 -DUSE_COREPCH=1 -DUSE_SCRIPTPCH=1 -DTOOLS=1 -DSCRIPTS=1 -DSERVERS=1 -DNOJEM=1 -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_FLAGS="-Werror" -DCMAKE_CXX_FLAGS="-Werror"
+  - cmake ../ -DWITH_WARNINGS=1 -DWITH_COREDEBUG=0 -DUSE_COREPCH=1 -DUSE_SCRIPTPCH=1 -DTOOLS=1 -DSCRIPTS=1 -DSERVERS=1 -DNOJEM=1 -DWITH_DYNAMIC_LINKING=1 -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_FLAGS="-Werror" -DCMAKE_CXX_FLAGS="-Werror" -DCMAKE_INSTALL_PREFIX=check_install
   - cd ..
   - sudo chmod +x contrib/check_updates.sh
 
@@ -36,4 +36,7 @@ script:
   - cat sql/updates/world/*.sql | mysql -utrinity -ptrinity world
   - mysql -uroot < sql/create/drop_mysql.sql
   - cd bin
-  - make -j 10 -k
+  - make -j 8 -k && make install
+  - cd check_install/bin
+  - ./authserver --version
+  - ./worldserver --version
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 17d4e1f051d..dda8f242feb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,9 +24,6 @@ endif(POLICY CMP0043)
 set(CMAKE_DISABLE_SOURCE_CHANGES ON)
 set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
 
-# build static libraries
-set(BUILD_SHARED_LIBS OFF)
-
 # Set RPATH-handing (CMake parameters)
 set(CMAKE_SKIP_BUILD_RPATH 0)
 set(CMAKE_BUILD_WITH_INSTALL_RPATH 0)
diff --git a/cmake/compiler/clang/settings.cmake b/cmake/compiler/clang/settings.cmake
index 261a55b285f..9a8cb85275e 100644
--- a/cmake/compiler/clang/settings.cmake
+++ b/cmake/compiler/clang/settings.cmake
@@ -18,3 +18,16 @@ endif()
 # -Wno-deprecated-register is needed to suppress 185 gsoap warnings on Unix systems.
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wno-narrowing -Wno-deprecated-register")
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG=1")
+
+if (WITH_DYNAMIC_LINKING)
+  # -fPIC is needed to allow static linking in shared libs.
+  # -fvisibility=hidden sets the default visibility to hidden to prevent exporting of all symbols.
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -fvisibility=hidden")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fvisibility=hidden")
+
+  # --no-undefined to throw errors when there are undefined symbols
+  # (caused through missing TRINITY_*_API macros).
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --no-undefined")
+
+  message(STATUS "Clang: Disallow undefined symbols")
+endif()
diff --git a/cmake/compiler/gcc/settings.cmake b/cmake/compiler/gcc/settings.cmake
index acd71e82fd9..d9eda767b8e 100644
--- a/cmake/compiler/gcc/settings.cmake
+++ b/cmake/compiler/gcc/settings.cmake
@@ -34,3 +34,15 @@ if( WITH_COREDEBUG )
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g3")
   message(STATUS "GCC: Debug-flags set (-g3)")
 endif()
+
+if (WITH_DYNAMIC_LINKING)
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -fvisibility=hidden -Wno-attributes")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fvisibility=hidden -Wno-attributes")
+
+  # Should break the build when there are TRINITY_*_API macros missing
+  # but it complains about missing references in precompiled headers.
+  # set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wl,--no-undefined")
+  # set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,--no-undefined")
+
+  message(STATUS "GCC: Enabled shared linking")
+endif()
diff --git a/cmake/compiler/msvc/settings.cmake b/cmake/compiler/msvc/settings.cmake
index 8af8033d809..994a5318ea4 100644
--- a/cmake/compiler/msvc/settings.cmake
+++ b/cmake/compiler/msvc/settings.cmake
@@ -74,6 +74,13 @@ if(NOT WITH_WARNINGS)
   message(STATUS "MSVC: Disabled generic compiletime warnings")
 endif()
 
+if (WITH_DYNAMIC_LINKING)
+  # C4251: needs to have dll-interface to be used by clients of class '...'
+  # C4275: non dll-interface class ...' used as base for dll-interface class '...'
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4251 /wd4275")
+  message(STATUS "MSVC: Enabled shared linking")
+endif()
+
 # Specify the maximum PreCompiled Header memory allocation limit
 # Fixes a compiler-problem when using PCH - the /Ym flag is adjusted by the compiler in MSVC2012, hence we need to set an upper limit with /Zm to avoid discrepancies)
 # (And yes, this is a verified , unresolved bug with MSVC... *sigh*)
diff --git a/cmake/options.cmake b/cmake/options.cmake
index d49393ed745..62810b2d3f2 100644
--- a/cmake/options.cmake
+++ b/cmake/options.cmake
@@ -13,6 +13,7 @@ option(SCRIPTS          "Build core with scripts included"
 option(TOOLS            "Build map/vmap/mmap extraction/assembler tools"              0)
 option(USE_SCRIPTPCH    "Use precompiled headers when compiling scripts"              1)
 option(USE_COREPCH      "Use precompiled headers when compiling servers"              1)
+option(WITH_DYNAMIC_LINKING "Enable dynamic library linking."                         0)
 option(WITH_WARNINGS    "Show all warnings during compile"                            0)
 option(WITH_COREDEBUG   "Include additional debug-code in core"                       0)
 set(WITH_SOURCE_TREE    "hierarchical" CACHE STRING "Build the source tree for IDE's.")
diff --git a/cmake/showoptions.cmake b/cmake/showoptions.cmake
index 537544ba10e..e6d709207b3 100644
--- a/cmake/showoptions.cmake
+++ b/cmake/showoptions.cmake
@@ -113,5 +113,15 @@ if ( HELGRIND )
   add_definitions(-DHELGRIND)
 endif()
 
-message("")
+if (WITH_DYNAMIC_LINKING)
+  message("")
+  message(" *** WITH_DYNAMIC_LINKING - INFO!")
+  message(" *** Will link against shared libraries!")
+  message(" *** Please note that this is an experimental feature!")
+  add_definitions(-DTRINITY_API_USE_DYNAMIC_LINKING)
+  set(BUILD_SHARED_LIBS ON)
+else()
+  set(BUILD_SHARED_LIBS OFF)
+endif()
 
+message("")
diff --git a/src/common/Define.h b/src/common/Define.h
index b34edb6a549..d03d26ad780 100644
--- a/src/common/Define.h
+++ b/src/common/Define.h
@@ -95,6 +95,45 @@
 #endif
 #endif //COMPILER == COMPILER_GNU
 
+#ifdef TRINITY_API_USE_DYNAMIC_LINKING
+#  if COMPILER == COMPILER_MICROSOFT
+#    define TC_API_EXPORT __declspec(dllexport)
+#    define TC_API_IMPORT __declspec(dllimport)
+#  elif COMPILER == COMPILER_GNU
+#    define TC_API_EXPORT __attribute__((visibility("default")))
+#    define TC_API_IMPORT
+#  else
+#    error compiler not supported!
+#  endif
+#else
+#  define TC_API_EXPORT
+#  define TC_API_IMPORT
+#endif
+
+#ifdef TRINITY_API_EXPORT_COMMON
+#  define TC_COMMON_API TC_API_EXPORT
+#else
+#  define TC_COMMON_API TC_API_IMPORT
+#endif
+
+#ifdef TRINITY_API_EXPORT_DATABASE
+#  define TC_DATABASE_API TC_API_EXPORT
+#else
+#  define TC_DATABASE_API TC_API_IMPORT
+#endif
+
+#ifdef TRINITY_API_EXPORT_SHARED
+#  define TC_SHARED_API TC_API_EXPORT
+#else
+#  define TC_SHARED_API TC_API_IMPORT
+#endif
+
+#ifdef TRINITY_API_EXPORT_GAME
+#  define TC_GAME_API TC_API_EXPORT
+#else
+#  define TC_GAME_API TC_API_IMPORT
+#endif
+
 #define UI64FMTD "%" PRIu64
 #define UI64LIT(N) UINT64_C(N)