如何修复“无法找到工具链文件”“CMake 错误：CMAKE_C_COMPILER 未设置，启用语言后”cmake libjpeg-turbo.so？

Question

我正在为不同的CPU架构生成libjpeg-turbo.so文件。

如果我在构建文件夹中执行以下 cmake，即使工具链文件存在于该路径中，我也会收到此错误：

$ cmake -G"Unix Makefiles" \
      -DANDROID_ABI=arm64-v8a \
      -DANDROID_ARM_MODE=arm \
      -DANDROID_PLATFORM=android-${21} \
      -DANDROID_TOOLCHAIN=${gcc} \
      -DCMAKE_ASM_FLAGS="--target=aarch64-linux-android${21}" \
      -DCMAKE_TOOLCHAIN_FILE=$/home/ingrid/Android/android-ndk-r16b/build/cmake/android.toolchain.cmake \
       /home/ingrid/Ingrid/NeoReader/libjpeg-turbo-master/

输出：

CMake Error at /usr/share/cmake-3.5/Modules/CMakeDetermineSystem.cmake:104 (message):
  Could not find toolchain file:
  $/home/ingrid/Android/android-ndk-r16b/build/cmake/android.toolchain.cmake
Call Stack (most recent call first):
  CMakeLists.txt:7 (project)


CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage
-- Configuring incomplete, errors occurred!

但是，如果我删除

-DANDROID_TOOLCHAIN=${gcc} \

和

-DCMAKE_TOOLCHAIN_FILE=$/home/ingrid/Android/android-ndk-r16b/build/cmake/android.toolchain.cmake \

那么我能够生成 .so 文件，但它生成的是 x86_64 而不是 arm64_v8a。以下是 cmake 及其输出：

$ cmake -G"Unix Makefiles" \
      -DANDROID_ABI=arm64-v8a \
      -DANDROID_ARM_MODE=arm \
      -DANDROID_PLATFORM=android-${21} \
      -DCMAKE_ASM_FLAGS="--target=aarch64-linux-android${21}" \
       /home/ingrid/Ingrid/NeoReader/libjpeg-turbo-master/

输出：

-- The C compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- CMAKE_BUILD_TYPE = Release
-- VERSION = 2.0.3, BUILD = 20190707
-- 64-bit build (x86_64)
-- CMAKE_INSTALL_PREFIX = /opt/libjpeg-turbo
-- CMAKE_INSTALL_BINDIR = bin (/opt/libjpeg-turbo/bin)
-- CMAKE_INSTALL_DATAROOTDIR =  (/opt/libjpeg-turbo)
-- CMAKE_INSTALL_DOCDIR = doc (/opt/libjpeg-turbo/doc)
-- CMAKE_INSTALL_INCLUDEDIR = include (/opt/libjpeg-turbo/include)
-- CMAKE_INSTALL_LIBDIR = lib64 (/opt/libjpeg-turbo/lib64)
-- CMAKE_INSTALL_MANDIR = man (/opt/libjpeg-turbo/man)
-- Shared libraries enabled (ENABLE_SHARED = 1)
-- Static libraries enabled (ENABLE_STATIC = 1)
-- 12-bit JPEG support disabled (WITH_12BIT = 0)
-- Arithmetic decoding support enabled (WITH_ARITH_DEC = 1)
-- Arithmetic encoding support enabled (WITH_ARITH_ENC = 1)
-- TurboJPEG API library enabled (WITH_TURBOJPEG = 1)
-- TurboJPEG Java wrapper disabled (WITH_JAVA = 0)
-- In-memory source/destination managers enabled (WITH_MEM_SRCDST = 1)
-- Emulating libjpeg API/ABI v6.2 (WITH_JPEG7 = 0, WITH_JPEG8 = 0)
-- libjpeg API shared library version = 62.3.0
-- Compiler flags =  -O3 -DNDEBUG
-- Linker flags =  
-- Looking for sys/types.h
-- Looking for sys/types.h - found
-- Looking for stdint.h
-- Looking for stdint.h - found
-- Looking for stddef.h
-- Looking for stddef.h - found
-- Check size of size_t
-- Check size of size_t - done
-- Check size of unsigned long
-- Check size of unsigned long - done
-- Performing Test HAVE_BUILTIN_CTZL
-- Performing Test HAVE_BUILTIN_CTZL - Success
-- Looking for include file locale.h
-- Looking for include file locale.h - found
-- Looking for include file stdlib.h
-- Looking for include file stdlib.h - found
-- Looking for include file sys/types.h
-- Looking for include file sys/types.h - found
-- Looking for memset
-- Looking for memset - found
-- Looking for memcpy
-- Looking for memcpy - found
-- Check size of unsigned char
-- Check size of unsigned char - done
-- Check size of unsigned short
-- Check size of unsigned short - done
-- Performing Test INCOMPLETE_TYPES
-- Performing Test INCOMPLETE_TYPES - Success
-- Compiler supports pointers to undefined structures.
-- Performing Test RIGHT_SHIFT_IS_UNSIGNED
-- Performing Test RIGHT_SHIFT_IS_UNSIGNED - Failed
-- Performing Test __CHAR_UNSIGNED__
-- Performing Test __CHAR_UNSIGNED__ - Failed
-- Performing Test INLINE_WORKS
-- Performing Test INLINE_WORKS - Success
-- INLINE = __inline__ __attribute__((always_inline)) (FORCE_INLINE = 1)
-- Performing Test HAVE_VERSION_SCRIPT
-- Performing Test HAVE_VERSION_SCRIPT - Success
-- Linker supports GNU-style version scripts
-- CMAKE_EXECUTABLE_SUFFIX = 
-- The ASM_NASM compiler identification is unknown
-- Found assembler: /usr/bin/nasm
-- CMAKE_ASM_NASM_COMPILER = /usr/bin/nasm
-- CMAKE_ASM_NASM_OBJECT_FORMAT = elf64
-- CMAKE_ASM_NASM_FLAGS =  -DELF -D__x86_64__ -DPIC 
-- SIMD extensions: x86_64 (WITH_SIMD = 1)
-- FLOATTEST = sse
-- RPM architecture = x86_64, DEB architecture = amd64
-- Configuring done
-- Generating done
CMake Warning:
  Manually-specified variables were not used by the project:

    ANDROID_ABI
    ANDROID_ARM_MODE
    ANDROID_PLATFORM
    CMAKE_ASM_FLAGS


-- Build files have been written to: /home/ingrid/Ingrid/NeoReader/libjpeg-turbo-master/build-arm64-v8a

您能否让我知道如何解决此工具链错误，以便我可以为arm64-v8a架构生成libjpeg-turbo.so文件？

谢谢你。

Answer 1

cmake 行中的以下参数是错误的：

...
-DCMAKE_TOOLCHAIN_FILE=$/home/ingrid/Android/android-ndk-r16b/build/cmake/android.toolchain.cmake \
...

$

符号告诉系统接下来是一个环境变量。所以您应该使用

-DCMAKE_TOOLCHAIN_FILE=$HOME/...

或

-DCMAKE_TOOLCHAIN_FILE=/home/ingrid/...

。

我不知道您从哪里得到该行的文档，但它可能提到了上面的选项之一。

顺便说一句，@Tsyvarev 的建议是正确的，他只是不知道其背后的原理。