【发布时间】：2019-03-13 21:35:56
【问题描述】：
我尝试在项目中使用 Poco C++ 库，但在为 Android 构建时遇到了一些问题。
我使用 Conan C++ 包管理器作为基础，但我将 Poco 源包含到项目中，并将其子目录包含到项目的顶级 CMakeLists.txt 中，以使过程更加透明。
如果我使用不依赖于 OpenSSL 的 Poco 库构建项目，它构建得很好。如果我添加 Poco 的 NetSSL，那么我会遇到一些与 math.h 相关的问题：
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Crypto/src/Cipher.cpp:15:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Crypto/include/Poco/Crypto/Cipher.h:22:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Foundation/include/Poco/RefCountedObject.h:22:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Foundation/include/Poco/MemoryPool.h:24:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Foundation/include/Poco/NestedDiagnosticContext.h:24:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Foundation/include/Poco/OrderedMap.h:28:
In file included from /home/uname/storage/projects/-some-project-/thirdparty/poco/Foundation/include/Poco/ordered_hash.h:31:
/home/uname/.conan/data/android-ndk/r18/theodelrieu/testing/package/2296cbf988942dec6e0ebdfef682b5c678acade8/sources/cxx-stl/llvm-libc++/include/cmath:313:9: error: no member named 'signbit' in the global
namespace; did you mean '__signbit'?
using ::signbit;
~~^
/usr/include/bits/mathcalls-helper-functions.h:25:20: note: '__signbit' declared here
__MATHDECL_1 (int, __signbit,, (_Mdouble_ __value))
据我所知，这是由于路径中早先包含的仅限 C 语言的 math.h 为 libc++ math.h 。有谁知道如何解决这个问题？
实际上，我正在尝试找到一种解决方案来构建和链接在使用柯南依赖项和构建要求时无法为 Android 正确构建的 Poco 库（由于 OpenSSL 依赖项的一些构建问题）或 Ubuntu 18.04 上的 android_ndk_installer/r19b@bincrafters/stable。因此，我尝试在不使用 Conan 包的情况下构建 Poco 库和 OpenSSL。
提前感谢您的任何提示或想法！
这是我的 Android 版柯南个人资料：
# --------------------------------------------------------------------------------------------------------------------
# PARAMETERS
#standalone_toolchain=/home/uname/Android/ndk/android-ndk-r19b/toolchains/llvm/prebuilt/linux-x86_64
target_host=armv7a-linux-androideabi
ar_host=arm-linux-androideabi
api_level=21
cc_compiler=clang
cxx_compiler=clang++
# --------------------------------------------------------------------------------------------------------------------
[settings]
os_build=Linux
arch_build=x86_64
compiler=clang
compiler.version=7.0
compiler.libcxx=libc++
os=Android
os.api_level=$api_level
arch=armv7
#Debug/Release
build_type=Debug
# --------------------------------------------------------------------------------------------------------------------
[build_requires]
android-ndk/r18@theodelrieu/testing
#android_ndk_installer/r19b@bincrafters/stable
# --------------------------------------------------------------------------------------------------------------------
[options]
*:shared=False
#Poco:no_asm=True
# --------------------------------------------------------------------------------------------------------------------
[env]
CONAN_CMAKE_FIND_ROOT_PATH=$standalone_toolchain/sysroot
PATH=[$standalone_toolchain/bin]
CHOST=$target_host
# Flags can be also appended after the path to the compiler
CC=$target_host$api_level-$cc_compiler
CXX=$target_host$api_level-$cxx_compiler
CMAKE_C_COMPILER=$CC
CMAKE_CXX_COMPILER=$CXX
AR=$ar_host-ar
AS=$ar_host-as
RANLIB=$target_host-ranlib
LD=$target_host-ld
STRIP=$target_host-strip
CFLAGS= -fPIE -fPIC -I$standalone_toolchain/include/c++/4.9.x
CXXFLAGS= -fPIE -fPIC -I$standalone_toolchain/include/c++/4.9.x
LDFLAGS= -pie
export ANDROID_API=$api_level
OpenSSL:compiler=clang
OpenSSL:options.no_zlib=True
和根 CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(-some-project-)
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()
## Experimental POCO
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/openssl/include) # Path whererever the openssl-dev headers are present
# When compiling the POCO C++ Libraries for a Android target, as well as when including POCO C++ Libraries headers in a project for a Android target, the preprocessor macro POCO_ANDROID must be defined. This is because the Android NDK GCC compiler does not provide a predefined macro that allows for reliable detection of an Android target.
IF(ANDROID)
SET(POCO_ANDROID)
ENDIF()
SET(ENABLE_ENCODINGS OFF)
SET(ENABLE_ENCODINGS_COMPILER OFF)
SET(ENABLE_XML OFF)
SET(ENABLE_JSON ON)
SET(ENABLE_MONGODB OFF)
SET(ENABLE_REDIS OFF)
SET(ENABLE_PDF OFF)
SET(ENABLE_UTIL OFF)
SET(ENABLE_NET ON)
SET(ENABLE_NETSSL ON)
SET(ENABLE_NETSSL_WIN OFF)
SET(ENABLE_CRYPTO OFF)
SET(ENABLE_DATA OFF)
SET(ENABLE_DATA_SQLITE OFF)
SET(ENABLE_DATA_MYSQL OFF)
SET(ENABLE_DATA_ODBC OFF)
SET(ENABLE_SEVENZIP OFF)
SET(ENABLE_ZIP OFF)
SET(ENABLE_APACHECONNECTOR OFF)
SET(ENABLE_CPPPARSER OFF)
SET(ENABLE_POCODOC OFF)
SET(ENABLE_PAGECOMPILER OFF)
SET(ENABLE_PAGECOMPILER_FILE2PAGE OFF)
SET(FORCE_OPENSSL OFF) # Force usage of OpenSSL even under windows
SET(ENABLE_TESTS OFF) # Set to OFF|ON (default is OFF) to control build of POCO tests & samples
SET(POCO_STATIC ON) # Set to OFF|ON (default is OFF) to control build of POCO as STATIC library
SET(POCO_UNBUNDLED OFF) # Set to OFF|ON (default is OFF) to control linking dependencies as external
SET(POCO_BUILD_TYPE "Release")
add_subdirectory(thirdparty/poco)
#SET(OPENSSL_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/openssl")
## \Experimental POCO
add_subdirectory(src)
IF(CMAKE_BUILD_TYPE STREQUAL "Debug")
add_subdirectory(test)
ENDIF()
PS：我是否使用了正确的方法，还是应该尝试以不同的方式包含和构建 Poco 库和 OpenSSL for Android？主要目标是 Android 和 iOS 设备以及用于开发和测试的本地 macOS 或 Linux。
【问题讨论】：
标签： android c++ cmake poco-libraries conan