[cmake-developers] Bug with CMAKE_ASM_COMPILER and Android NDK

[Robert Dailey]

So I have two environment variables:

ANDROID_NDK = E:\android\ndk
ANDROID_NDK_72 = E:\android\ndk_72

In my toolchain file, I do this:



set( CMAKE_SYSTEM_NAME Android )
set( CMAKE_SYSTEM_VERSION 15 ) # API level
set( CMAKE_ANDROID_ARCH_ABI armeabi-v7a )
set( CMAKE_ANDROID_STL_TYPE c++_shared )
set( CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION clang )

# ANDROID_NDK_72 represents a separate path to the NDK for 7.2 frontend
# builds and later. This is to make it less painful to convert between
# Crystax (7.1.x) and official NDK, which was restored in version 7.2.
string(REGEX REPLACE "\\\\" "/" ndk_path "$ENV{ANDROID_NDK_72}")
if( NOT EXISTS ${ndk_path} )
    string(REGEX REPLACE "\\\\" "/" ndk_path "$ENV{ANDROID_NDK}")
endif()

set( CMAKE_ANDROID_NDK ${ndk_path} )
unset(ndk_path)



This works fine, until you do something like this in your CMake scripts:


enable_language(ASM)


CMake appears to find clang.exe in the wrong place (It's using
ANDROID_NDK directly somehow instead of using the CMAKE_ANDROID_NDK I
set from my toolchain file). Output from CMake is at the bottom of
this email. The repository I'm configuring is here:

https://github.com/Orphis/boost-cmake

Logs:


$ cmake .. -GNinja
-DCMAKE_TOOLCHAIN_FILE="E:\code\_external\\android_armeabi-v7a.toolchain.cmake"
    -DCMAKE_BUILD_TYPE=Release     -DCMAKE_INSTALL_PREFIX=_install
-DBOOST_LOCALE_ENABLE_ICU_BACKEND=OFF
-DBOOST_LOCALE_ENABLE_ICONV_BACKEND=OFF
-- Android: Targeting API '15' with architecture 'arm', ABI
'armeabi-v7a', and processor 'armv7-a'
-- Android: Selected Clang toolchain 'arm-linux-androideabi-clang'
with GCC toolchain 'arm-linux-androideabi-4.9'
-- The C compiler identification is Clang 5.0.300080
-- The CXX compiler identification is Clang 5.0.300080
-- Check for working C compiler:
E:/android/ndk_72/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe
-- Check for working C compiler:
E:/android/ndk_72/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe
-- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler:
E:/android/ndk_72/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe
-- Check for working CXX compiler:
E:/android/ndk_72/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe
-- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Boost found: 1.63.0 E:/code/_external/boost-cmake/boost/boost_1_63_0
-- Boost found: 1.63.0 E:/code/_external/boost-cmake/boost/boost_1_63_0
-- Standalone mode detected
-- Looking for __linux__
-- Looking for __linux__ - found
-- Looking for _WIN32
-- Looking for _WIN32 - not found
-- Looking for __APPLE__
-- Looking for __APPLE__ - not found
-- Looking for __ANDROID__
-- Looking for __ANDROID__ - found
-- Looking for __FreeBSD__
-- Looking for __FreeBSD__ - not found
-- The ASM compiler identification is unknown
-- Found assembler:
E:/android/ndk/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe
CMake Error at libs/context.cmake:34 (enable_language):
  The CMAKE_ASM_COMPILER:

    E:/android/ndk/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "ASM" or the CMake cache entry CMAKE_ASM_COMPILER to the full path
  to the compiler, or to the compiler name if it is in the PATH.
Call Stack (most recent call first):
  CMakeLists.txt:63 (include)


-- Warning: Did not find file Compiler/-ASM