CMake: (Properly) build glfw separately with CMake

This reverts commit 2d6fb5c628,
and adds a fix for Alien::raylib's test failures.

The tests failed because the resulting static library didn't reexport
GLFW symbols. As a fix, we now have GLFW create a CMake "object library"
target that we can link with both the static and shared raylib.

This is arguably ugly... Proper fix would probably be a GLFW upstream
object library target.

Closes #536.

src/CMakeLists.txt

@@ -10,17 +10,37 @@ include("CMakeOptions.txt")
 configure_file(config.h.in ${CMAKE_BINARY_DIR}/cmake/config.h)
 include_directories(${CMAKE_BINARY_DIR})
 
-include("../utils.cmake")
+if(MACOS_FATLIB)
+    if (CMAKE_OSX_ARCHITECTURES)
+        message(FATAL_ERROR "User supplied -DCMAKE_OSX_ARCHITECTURES overrides -DMACOS_FATLIB=ON")
+    else()
+        SET(CMAKE_OSX_ARCHITECTURES "x86_64;i386")
+    endif()
+endif()
 
 # Get the sources together
 file(GLOB raylib_sources *.c)
+list(REMOVE_ITEM raylib_sources ${CMAKE_CURRENT_SOURCE_DIR}/rglfw.c)
 
-if(glfw3_FOUND)
-  list(REMOVE_ITEM raylib_sources ${CMAKE_CURRENT_SOURCE_DIR}/rglfw.c)
-else()
+if(NOT glfw3_FOUND)
+  set(GLFW_BUILD_DOCS OFF CACHE BOOL "" FORCE)
+  set(GLFW_BUILD_TESTS OFF CACHE BOOL "" FORCE)
+  set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+  set(GLFW_INSTALL OFF CACHE BOOL "" FORCE)
+  set(BUILD_SHARED_LIBS OFF CACHE BOOL " " FORCE)
+  set(GLFW_USE_WAYLAND ${USE_WAYLAND} CACHE BOOL "" FORCE)
+  if (USE_PIC OR SHARED)
+    set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+  endif()
+
+  add_subdirectory(external/glfw)
   include_directories(external/glfw/include)
+
+  list(APPEND raylib_sources $<TARGET_OBJECTS:glfw_objlib>)
 endif()
 
+include("../utils.cmake")
+
 if(USE_AUDIO)
   file(GLOB stb_vorbis external/stb_vorbis.c)
   file(GLOB mini_al external/mini_al.c ${stb_vorbis})
@@ -51,7 +71,6 @@ if(${PLATFORM} MATCHES "Desktop")
   # See: https://github.com/raysan5/raylib/issues/341
   if(APPLE)
     set(GRAPHICS "GRAPHICS_API_OPENGL_33")
-    set_source_files_properties(rglfw.c PROPERTIES COMPILE_FLAGS "-x objective-c")
     link_libraries("${LIBS_PRIVATE}")
   elseif(WIN32)
     add_definitions(-D_CRT_SECURE_NO_WARNINGS)
@@ -76,14 +95,6 @@ elseif(${PLATFORM} MATCHES "Raspberry Pi")
   set(GRAPHICS "GRAPHICS_API_OPENGL_ES2")
 endif()
 
-if(MACOS_FATLIB)
-    if (CMAKE_OSX_ARCHITECTURES)
-        message(FATAL_ERROR "User supplied -DCMAKE_OSX_ARCHITECTURES overrides -DMACOS_FATLIB=ON")
-    else()
-        SET(CMAKE_OSX_ARCHITECTURES "x86_64;i386")
-    endif()
-endif()
-
 # Which platform?
 if(${PLATFORM} MATCHES "PLATFORM_DESKTOP")
 
@@ -100,7 +111,7 @@ if(${PLATFORM} MATCHES "PLATFORM_DESKTOP")
     set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
     set(CMAKE_MACOSX_RPATH ON)
 
-    target_link_libraries(${RAYLIB}_shared ${LIBS_PRIVATE})
+    target_link_libraries(${RAYLIB}_shared ${LIBS_PRIVATE} glfw ${GLFW_LIBRARIES})
     if (UNIX AND ${FILESYSTEM_LACKS_SYMLINKS})
       MESSAGE(WARNING "Can't version UNIX shared library on file system without symlink support")
     else()
@@ -137,6 +148,7 @@ if(${PLATFORM} MATCHES "PLATFORM_DESKTOP")
     )
 
     set(PKG_CONFIG_LIBS_PRIVATE ${__PKG_CONFIG_LIBS_PRIVATE})
+    target_link_libraries(${RAYLIB} glfw ${GLFW_LIBRARIES})
 
     if (WITH_PIC)
       set_property(TARGET ${RAYLIB} PROPERTY POSITION_INDEPENDENT_CODE ON)

src/external/glfw/src/CMakeLists.txt

@@ -92,7 +92,9 @@ if (${CMAKE_C_COMPILER_ID} STREQUAL GNU OR ${CMAKE_C_COMPILER_ID} STREQUAL Clang
         COMPILE_FLAGS -Wdeclaration-after-statement)
 endif()
 
-add_library(glfw ${glfw_SOURCES} ${glfw_HEADERS})
+add_library(glfw_objlib OBJECT ${glfw_SOURCES} ${glfw_HEADERS})
+add_library(glfw $<TARGET_OBJECTS:glfw_objlib>)
+
 set_target_properties(glfw PROPERTIES
                       OUTPUT_NAME ${GLFW_LIB_NAME}
                       VERSION ${GLFW_VERSION}
@@ -100,11 +102,11 @@ set_target_properties(glfw PROPERTIES
                       POSITION_INDEPENDENT_CODE ON
                       FOLDER "GLFW3")
 
-target_compile_definitions(glfw PRIVATE _GLFW_USE_CONFIG_H)
-target_include_directories(glfw PUBLIC
+target_compile_definitions(glfw_objlib PRIVATE _GLFW_USE_CONFIG_H)
+target_include_directories(glfw_objlib PUBLIC
                            "$<BUILD_INTERFACE:${GLFW_SOURCE_DIR}/include>"
                            "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include>")
-target_include_directories(glfw PRIVATE
+target_include_directories(glfw_objlib PRIVATE
                            "${GLFW_SOURCE_DIR}/src"
                            "${GLFW_BINARY_DIR}/src"
                            ${glfw_INCLUDE_DIRS})
@@ -113,11 +115,11 @@ target_include_directories(glfw PRIVATE
 # the inclusion of stddef.h (by glfw3.h), which is itself included before
 # win32_platform.h.  We define them here until a saner solution can be found
 # NOTE: MinGW-w64 and Visual C++ do /not/ need this hack.
-target_compile_definitions(glfw PRIVATE
+target_compile_definitions(glfw_objlib PRIVATE
                            "$<$<BOOL:${MINGW}>:UNICODE;WINVER=0x0501>")
 
 # Enable a reasonable set of warnings (no, -Wextra is not reasonable)
-target_compile_options(glfw PRIVATE
+target_compile_options(glfw_objlib PRIVATE
                        "$<$<C_COMPILER_ID:Clang>:-Wall>"
                        "$<$<C_COMPILER_ID:GNU>:-Wall>")
 
@@ -135,7 +137,7 @@ if (BUILD_SHARED_LIBS)
         endif()
     elseif (APPLE)
         # Add -fno-common to work around a bug in Apple's GCC
-        target_compile_options(glfw PRIVATE "-fno-common")
+        target_compile_options(glfw_objlib PRIVATE "-fno-common")
 
         set_target_properties(glfw PROPERTIES
                               INSTALL_NAME_DIR "lib${LIB_SUFFIX}")