Support the auto-compiling for host protoc when cross-compiling.

cmake/cross_compiling/android.cmake

@@ -110,9 +110,22 @@ IF(${CMAKE_VERSION} VERSION_LESS "3.7.0")
         ENDIF()
     ENDIF()
     SET(ANDROID_TOOLCHAIN_PREFIX "${ANDROID_TOOLCHAIN_ROOT}/bin/${ANDROID_TOOLCHAIN_NAME}-")
-     
-    SET(CMAKE_C_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}gcc")
-    SET(CMAKE_CXX_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}g++")
+
+    IF(EXISTS "${ANDROID_TOOLCHAIN_PREFIX}gcc")
+        SET(CMAKE_C_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}gcc")
+    ELSE()
+        MESSAGE(FATAL_ERROR "Cannot find C compiler: ${ANDROID_TOOLCHAIN_PREFIX}gcc")
+    ENDIF()
+
+    IF(EXISTS "${ANDROID_TOOLCHAIN_PREFIX}g++")
+        SET(CMAKE_CXX_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}g++")
+    ELSE()
+        MESSAGE(FATAL_ERROR "Cannot find CXX compiler: ${ANDROID_TOOLCHAIN_PREFIX}g++")
+    ENDIF()
+
+    IF(EXISTS "${ANDROID_TOOLCHAIN_PREFIX}gfortran")
+        SET(CMAKE_Fortran_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}gfortran")
+    ENDIF()
 
     # Toolchain and ABI specific flags.
     SET(ANDROID_COMPILER_FLAGS "-ffunction-sections -fdata-sections -finline-limit=64")

cmake/external/protobuf.cmake

@@ -14,42 +14,41 @@
 
 INCLUDE(ExternalProject)
 
-set(PROTOBUF_VERSION 3.1)
-FIND_PACKAGE(Protobuf ${PROTOBUF_VERSION})
+FUNCTION(build_protobuf TARGET_NAME BUILD_FOR_HOST)
+    SET(PROTOBUF_SOURCES_DIR ${THIRD_PARTY_PATH}/${TARGET_NAME})
+    SET(PROTOBUF_INSTALL_DIR ${THIRD_PARTY_PATH}/install/${TARGET_NAME})
 
-IF(PROTOBUF_FOUND)
-    EXEC_PROGRAM(${PROTOBUF_PROTOC_EXECUTABLE} ARGS --version OUTPUT_VARIABLE PROTOBUF_VERSION)
-    STRING(REGEX MATCH "[0-9]+.[0-9]+" PROTOBUF_VERSION "${PROTOBUF_VERSION}")
-    IF (${PROTOBUF_VERSION} VERSION_LESS "3.1.0")
-        SET(PROTOBUF_FOUND OFF)
-    ENDIF()
-ENDIF(PROTOBUF_FOUND)
-
-IF(NOT PROTOBUF_FOUND)
-    SET(PROTOBUF_SOURCES_DIR ${THIRD_PARTY_PATH}/protobuf)
-    SET(PROTOBUF_INSTALL_DIR ${THIRD_PARTY_PATH}/install/protobuf)
-    SET(PROTOBUF_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" CACHE PATH "protobuf include directory." FORCE)
+    SET(${TARGET_NAME}_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" PARENT_SCOPE)
+    SET(${TARGET_NAME}_LITE_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_PROTOC_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotoc${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_PROTOC_EXECUTABLE
+        "${PROTOBUF_INSTALL_DIR}/bin/protoc${EXECUTABLE_SUFFIX}"
+         PARENT_SCOPE)
 
-    IF(WIN32)
-        SET(PROTOBUF_LITE_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite.lib" CACHE FILEPATH "protobuf lite library." FORCE)
-        SET(PROTOBUF_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf.lib" CACHE FILEPATH "protobuf library." FORCE)
-        SET(PROTOBUF_PROTOC_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotoc.lib" CACHE FILEPATH "protoc library." FORCE)
-        SET(PROTOBUF_PROTOC_EXECUTABLE "${PROTOBUF_INSTALL_DIR}/bin/protoc.exe" CACHE FILEPATH "protobuf executable." FORCE)
-    ELSE(WIN32)
-        SET(PROTOBUF_LITE_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite.a" CACHE FILEPATH "protobuf lite library." FORCE)
-        SET(PROTOBUF_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf.a" CACHE FILEPATH "protobuf library." FORCE)
-        SET(PROTOBUF_PROTOC_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotoc.a" CACHE FILEPATH "protoc library." FORCE)
-        SET(PROTOBUF_PROTOC_EXECUTABLE "${PROTOBUF_INSTALL_DIR}/bin/protoc" CACHE FILEPATH "protobuf executable." FORCE)
-    ENDIF(WIN32)
+    SET(OPTIONAL_CACHE_ARGS "")
+    SET(OPTIONAL_ARGS "")
+    IF(BUILD_FOR_HOST)
+        SET(OPTIONAL_ARGS "-Dprotobuf_WITH_ZLIB=OFF")
+    ELSE()
+        SET(OPTIONAL_ARGS
+            "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}"
+            "-DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}"
+            "-DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}"
+            "-DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}"
+            "-Dprotobuf_WITH_ZLIB=ON"
+            "-DZLIB_ROOT:FILEPATH=${ZLIB_ROOT}")
+        SET(OPTIONAL_CACHE_ARGS "-DZLIB_ROOT:STRING=${ZLIB_ROOT}")
+    ENDIF()
 
     ExternalProject_Add(
-        protobuf
+        ${TARGET_NAME}
         ${EXTERNAL_PROJECT_LOG_ARGS}
         PREFIX          ${PROTOBUF_SOURCES_DIR}
         UPDATE_COMMAND  ""
@@ -57,11 +56,9 @@ IF(NOT PROTOBUF_FOUND)
         GIT_REPOSITORY  "https://github.com/google/protobuf.git"
         GIT_TAG         "9f75c5aa851cd877fb0d93ccc31b8567a6706546"
         CONFIGURE_COMMAND
-        ${CMAKE_COMMAND} ${PROTOBUF_SOURCES_DIR}/src/protobuf/cmake
+        ${CMAKE_COMMAND} ${PROTOBUF_SOURCES_DIR}/src/${TARGET_NAME}/cmake
+            ${OPTIONAL_ARGS}
             -Dprotobuf_BUILD_TESTS=OFF
-            -DZLIB_ROOT:FILEPATH=${ZLIB_ROOT}
-            -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
-            -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
             -DCMAKE_POSITION_INDEPENDENT_CODE=ON
             -DCMAKE_BUILD_TYPE=Release
             -DCMAKE_INSTALL_PREFIX=${PROTOBUF_INSTALL_DIR}
@@ -71,10 +68,42 @@ IF(NOT PROTOBUF_FOUND)
             -DCMAKE_BUILD_TYPE:STRING=Release
             -DCMAKE_VERBOSE_MAKEFILE:BOOL=OFF
             -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
-            -DZLIB_ROOT:STRING=${ZLIB_ROOT}
+            ${OPTIONAL_CACHE_ARGS}
     )
 
-    LIST(APPEND external_project_dependencies protobuf)
+    LIST(APPEND external_project_dependencies ${TARGET_NAME} PARENT_SCOPE)
+ENDFUNCTION()
+
+IF(NOT CMAKE_CROSSCOMPILING)
+    SET(PROTOBUF_VERSION 3.1)
+    FIND_PACKAGE(Protobuf ${PROTOBUF_VERSION})
+
+    IF(PROTOBUF_FOUND)
+        EXEC_PROGRAM(${PROTOBUF_PROTOC_EXECUTABLE} ARGS --version OUTPUT_VARIABLE PROTOBUF_VERSION)
+        STRING(REGEX MATCH "[0-9]+.[0-9]+" PROTOBUF_VERSION "${PROTOBUF_VERSION}")
+        IF (${PROTOBUF_VERSION} VERSION_LESS "3.1.0")
+            SET(PROTOBUF_FOUND OFF)
+        ENDIF()
+    ENDIF(PROTOBUF_FOUND)
+ELSE()
+    build_protobuf(protobuf_host TRUE)
+    SET(PROTOBUF_PROTOC_EXECUTABLE ${protobuf_host_PROTOC_EXECUTABLE}
+        CACHE FILEPATH "protobuf executable." FORCE)
+ENDIF()
+
+IF(NOT PROTOBUF_FOUND)
+    build_protobuf(protobuf FALSE)
+    SET(PROTOBUF_INCLUDE_DIR ${protobuf_INCLUDE_DIR}
+        CACHE PATH "protobuf include directory." FORCE)
+    IF(NOT CMAKE_CROSSCOMPILING)
+        SET(PROTOBUF_PROTOC_EXECUTABLE ${protobuf_PROTOC_EXECUTABLE}
+            CACHE FILEPATH "protobuf executable." FORCE)
+    ENDIF()
+    SET(PROTOBUF_LITE_LIBRARY ${protobuf_LITE_LIBRARY} CACHE FILEPATH "protobuf lite library." FORCE)
+    SET(PROTOBUF_LIBRARY ${protobuf_LIBRARY} CACHE FILEPATH "protobuf library." FORCE)
+    SET(PROTOBUF_PROTOC_LIBRARY ${protobuf_PROTOC_LIBRARY} CACHE FILEPATH "protoc library." FORCE)
 ENDIF(NOT PROTOBUF_FOUND)
 
+MESSAGE(STATUS "Protobuf protoc executable: ${PROTOBUF_PROTOC_EXECUTABLE}")
+MESSAGE(STATUS "Protobuf library: ${PROTOBUF_LIBRARY}")
 INCLUDE_DIRECTORIES(${PROTOBUF_INCLUDE_DIR})