解决Android bp build error: dependency "..." of "..." missing variant

Android O上开始谷歌加大力度推广使用新的soong编译，随之而来的影响就是原先在Android.mk文件需要转换为Android.bp文件做编译配置。

使用soong提供的androidmk命令可以把Android.mk文件转换为Android.bp文件，但是对于一些复杂的mk语法，转换的结果往往不能像原先的Android.mk那样可以正常编译出想要的结果。这就需要将转换出的Android.bp做进一步的修改，以符合原来的编译需求。

androidmk Android.mk > Android.bp

下面来说说我所遇到的dependency "..." of "..." missing variant 错误的解决过程:

1.Android.mk转换成Android.bp：

原先的Android.mk中有如下配置，目的是需要将编译出两个版本的tinyalsa, Android版和Host版，且名称相同。以下是Android.mk中tinyalsa的两个版本的配置：

include $(CLEAR_VARS)

LOCAL_C_INCLUDES:= external/tinyalsa/include

LOCAL_SRC_FILES:= mixer.c pcm.c

LOCAL_MODULE := libtinyalsa

LOCAL_SHARED_LIBRARIES:= libcutils libutils liblog

LOCAL_MODULE_TAGS := optional

LOCAL_CFLAGS += -Werror

ifeq ($(strip $(NXP_SMARTPA_SUPPORT)),tfa9895)

LOCAL_CFLAGS += -DNXP_TFA9895_SUPPORT

LOCAL_C_INCLUDES+= device/vendor/msm8937/TFA9895/app/exTfa98xx/inc

LOCAL_SHARED_LIBRARIES+= libtfa9895

endif

include $(BUILD_SHARED_LIBRARY)

ifeq ($(HOST_OS), linux)

include $(CLEAR_VARS)

LOCAL_C_INCLUDES:= external/tinyalsa/include

LOCAL_SRC_FILES:= mixer.c pcm.c

LOCAL_MODULE := libtinyalsa

LOCAL_STATIC_LIBRARIES:= libcutils libutils liblog

LOCAL_CFLAGS += -Werror

include $(BUILD_HOST_STATIC_LIBRARY)

endif

原android版tinyalsa是shared_library, host版tinyalsa是static_library, 用androidmk命令转换成bp文件后内容如下：

cc_library_shared {

include_dirs: ["external/tinyalsa/include"] + ["device/vendor/msm8937/TFA9895/app/exTfa98xx/inc"] + ["device/vendor/msm8937/TFA9891/app/exTfa98xx/inc"],

// ANDROIDMK TRANSLATION ERROR: unsupported conditional

// ifeq ($(strip $(NXP_SMARTPA_SUPPORT)),tfa9895)

// ANDROIDMK TRANSLATION ERROR: endif from unsupported contitional

// endif

// ANDROIDMK TRANSLATION ERROR: endif from unsupported contitional

// endif

// ANDROIDMK TRANSLATION ERROR: unsupported conditional

// ifeq ($(strip $(NXP_SMARTPA_SUPPORT)),tfa9895)

srcs: [

"mixer.c",

"pcm.c",

],

name: "libtinyalsa",

shared_libs: [

"libcutils",

"libutils",

],

cflags: ["-Werror"] + ["-DNXP_TFA9895_SUPPORT"] + ["-DNXP_TFA9895_SUPPORT"],

shared_libs: ["libtfa9895"],

// ANDROIDMK TRANSLATION ERROR: endif from unsupported contitional

// endif

// ANDROIDMK TRANSLATION ERROR: endif from unsupported contitional

// endif

}

cc_library_host_static {

include_dirs: ["external/tinyalsa/include"],

srcs: [

"mixer.c",

"pcm.c",

],

name: "libtinyalsa",

static_libs: [

"libcutils",

"libutils",

],

cflags:["-Werror"],

target:{

not_linux:{

enabled:false,

},

},

}

转换后有两个名字相同的libtinyalsa module。

因为项目需求，在libtinyalsa Android版中添加了共享库依赖：libtfa9895:

所以现在的库依赖关系变为：

Android: libtinyalsa -> libcutils, libutils,libtfa9895

Host: libtinyalsa -> libcutils, libutils

2. Android.mk转为Android.bp之后，手动修改，删除名字相同的多余module.

bp文件定义的一个规则是，可以定义很多种很多个module，每个module必须有一个名字，且名字必须唯一不重复。这是因为bp文件没有判断逻辑，不能像mk中那样根据不同的编译选项选择不同的版本。

在原Android.mk中定义了两个名字相同的tinyalsa, 一个是Android版，一个是Host版。转成bp后，出现了两个名字相同的tinyalsa module,一个是cc_library_shared, 一个是cc_library_host_static。而根据bp的module名字不重复规则，这种情况是不允许的，所以我们做的第一个修改是将两个module合并为一个，然后通过**host_supported: true**使其支持host;

又因为原来的两个module，一个为shared,一个为static，所以第二个修改是合并后的module类型为cc_library, 这样才能同时包含shared与static两种不同的属性类型。

修改后的Android.bp：

cc_library {

include_dirs: ["device/vendor/msm8937/TFA9895/app/exTfa98xx/inc"],

name: "libtinyalsa",

host_supported: true,

vendor_available: true,

srcs: [

"mixer.c",

"pcm.c",

],

shared_libs: [

"libcutils",

"libutils",

"libtfa9895",

],

cflags: ["-Werror", "-Wno-macro-redefined"]+ ["-DNXP_TFA9895_SUPPORT"],

export_include_dirs: ["include"],

local_include_dirs: ["include"],

target: {

darwin: {

enabled: false,

},

},

}

下面要说的编译错误就是因为在tinyplay和tinyalsa中添加了host_supported引起的：

error: external/tinyalsa/Android.bp:1:1: dependency "libtfa9895" of "libtinyalsa" missing variant:

arch:linux_x86_64, link:shared

available variants:

arch:android_arm64_armv8-a, link:shared, image:core

arch:android_arm_armv7-a-neon_cortex-a53, link:shared, image:core

从出错信息来看，是由于libtfa9895中不支持linux_x86_64平台的编译。

以下是libtfa9895转换为Android.bp后的配置：

cc_library_shared {

local_include_dirs: [

"srv/inc",

"tfa/inc",

"utl/inc",

"hal/inc",

"hal/src",

"hal/src/lxScribo",

"srv/src/iniFile",

"app/exTfa98xx/inc",

],

export_include_dirs: [

"srv/inc",

"tfa/inc",

"utl/inc",

"hal/inc",

"hal/src",

"hal/src/lxScribo",

"srv/src/iniFile",

"app/exTfa98xx/inc",

],

srcs: ["app/exTfa98xx/src/main_container.c"],

name: "libtfa9895",

shared_libs: [

"libcutils",

],

static_libs: [

"libsrv",

"libtfa",

"libhal",

],

}

3. 除错过程：

libtinyalsa依赖库有三个，libcutils, libutils, libtfa9895,

而log中只提供libtfa9895有错，查看libcutils和libutils的配置发现，这两个库里的配置信息都有添加host_supported，而libtfa9895没有，所以尝试在libtfa9895中添加host_supported配置后重新编译，

然后出现了相同的错误提示，只不过这次提示libtfa9895依赖的三个库(libsrv/libtfa/libhal)不支持host。看来在有host_supported配置的库中，其依赖库也必须是host_supported的。

在libsrv/libtfa/libhal中分别添加host_supported配置后，再次提示这三个库依赖的libutils不支持host.

查看libutils的配置发现libutils有添加host_supported，这里怎么回事呢？

cc_library {

name: "libutils",

vendor_available: true,

host_supported: true,

srcs: [

....

],

cflags: ["-Werror"],

include_dirs: ["external/safe-iop/include"],

header_libs: [

"libutils_headers",

],

export_header_lib_headers: [

"libutils_headers",

],

arch: {

mips: {

cflags: ["-DALIGN_DOUBLE"],

},

},

target: {

android: {

srcs: [

"Looper.cpp",

"ProcessCallStack.cpp",

"Trace.cpp",

],

cflags: ["-fvisibility=protected"],

shared_libs: [

"libbacktrace",

"libcutils",

"libdl",

"liblog",

"libvndksupport",

],

sanitize: {

misc_undefined: ["integer"],

},

},

host: {

cflags: ["-DLIBUTILS_NATIVE=1"],

shared: {

enabled: false,

},

},

linux: {

srcs: [

"Looper.cpp",

"ProcessCallStack.cpp",

],

},

linux_bionic: {

enabled: true,

srcs: [

"Looper.cpp",

"ProcessCallStack.cpp",

],

},

darwin: {

cflags: ["-Wno-unused-parameter"],

},

// Under MinGW, ctype.h doesn't need multi-byte support

windows: {

cflags: ["-DMB_CUR_MAX=1"],

enabled: true,

},

},

clang: true,

}

仔细分析libutils中的配置，发现原来在target:下的host配置，将shared属性设置成了false，就是说在编译Android版时，libutils可以作为shared lib引用，但是在host版中，只能做为static lib引用。

host: {

cflags: ["-DLIBUTILS_NATIVE=1"],

shared: {

enabled: false,

},

},

所以对引用libutils的module中，做了如下修改，首先删除libutils的引用，然后添加如下配置：

target: {

android: {

cflags: ["-DAndroid"],

shared_libs: [

"libutils",

],

},

host: {

static_libs: ["libutils"],

},

},

android版以shared lib引用libutils, host版以static lib引用。

修改后的完整的libtfa9895的配置信息如下：

cc_library_shared {

local_include_dirs: [

"srv/inc",

"tfa/inc",

"utl/inc",

"hal/inc",

"hal/src",

"hal/src/lxScribo",

"srv/src/iniFile",

"app/exTfa98xx/inc",

],

export_include_dirs: [

"srv/inc",

"tfa/inc",

"utl/inc",

"hal/inc",

"hal/src",

"hal/src/lxScribo",

"srv/src/iniFile",

"app/exTfa98xx/inc",

],

srcs: ["app/exTfa98xx/src/main_container.c"],

name: "libtfa9895",

host_supported: true,

shared_libs: [

"libcutils",

],

static_libs: [

"libsrv",

"libtfa",

"libhal",

],

target: {

android: {

cflags: ["-DAndroid"],

shared_libs: [

"libutils",

],

},

host: {

static_libs: ["libutils"],

},

},

}

所以修改完成后，编译通过。

4. 进一步完善

回到前面我们libtinyalsa的定义，在原mk中android版 libtinyalsa是shared library, host版是static library，而转成bp后，libtinyalsa合并成了一个cc_library，但是并未对android版与host版区分其shared/static属性。

参考libutils中的方法，可以对libtinyalsa target为android与host两个版本的shared属性设置为不同的值。

target: {

android:{

shared:{

enabled: true,

},

},

host:{

cflags: ["-DLIBUTILS_NATIVE=1"],

shared: {

enabled: false,

},},

},