Android: Select NDK host tag while determining system

The host tag is tied to the host platform and does not depend on any
specific language or compiler.

Modules/Platform/Android-Determine.cmake

@@ -198,6 +198,33 @@ if(NOT CMAKE_SYSTEM_VERSION MATCHES "^[0-9]+$")
   message(FATAL_ERROR "Android: The API specified by CMAKE_SYSTEM_VERSION='${CMAKE_SYSTEM_VERSION}' is not an integer.")
 endif()
 
+if(CMAKE_ANDROID_NDK)
+  # Identify the host platform.
+  if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Darwin")
+    if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "darwin-x86_64")
+    else()
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "darwin-x86")
+    endif()
+  elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux")
+    if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "linux-x86_64")
+    else()
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "linux-x86")
+    endif()
+  elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
+    if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "AMD64")
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "windows-x86_64")
+    else()
+      set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "windows")
+    endif()
+  else()
+    message(FATAL_ERROR "Android: Builds hosted on '${CMAKE_HOST_SYSTEM_NAME}' not supported.")
+  endif()
+else()
+  set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "")
+endif()
+
 # https://developer.android.com/ndk/guides/abis.html
 
 set(_ANDROID_ABI_arm64-v8a_PROC     "aarch64")
@@ -342,6 +369,7 @@ if(CMAKE_ANDROID_NDK)
   string(APPEND CMAKE_SYSTEM_CUSTOM_CODE
     "set(CMAKE_ANDROID_ARCH_HEADER_TRIPLE \"${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}\")\n"
     "set(CMAKE_ANDROID_NDK_DEPRECATED_HEADERS \"${CMAKE_ANDROID_NDK_DEPRECATED_HEADERS}\")\n"
+    "set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG \"${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG}\")\n"
     )
 endif()
 

Modules/Platform/Android/Determine-Compiler-NDK.cmake

@@ -195,40 +195,16 @@ if(NOT _ANDROID_TOOL_PREFIX AND "${_ANDROID_TOOL_NAME}" MATCHES "^(.*-)[0-9.]+$"
   set(_ANDROID_TOOL_PREFIX "${CMAKE_MATCH_1}")
 endif()
 
-# Identify the host platform.
-if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Darwin")
-  if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
-    set(_ANDROID_HOST_DIR "darwin-x86_64")
-  else()
-    set(_ANDROID_HOST_DIR "darwin-x86")
-  endif()
-elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux")
-  if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
-    set(_ANDROID_HOST_DIR "linux-x86_64")
-  else()
-    set(_ANDROID_HOST_DIR "linux-x86")
-  endif()
-elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
-  if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "AMD64")
-    set(_ANDROID_HOST_DIR "windows-x86_64")
-  else()
-    set(_ANDROID_HOST_DIR "windows")
-  endif()
-else()
-  message(FATAL_ERROR "Android: Builds hosted on '${CMAKE_HOST_SYSTEM_NAME}' not supported.")
-endif()
-
 # Help CMakeFindBinUtils locate things.
 set(_CMAKE_TOOLCHAIN_PREFIX "${_ANDROID_TOOL_PREFIX}")
 
-set(_ANDROID_TOOL_NDK_TOOLCHAIN_HOST_TAG "${_ANDROID_HOST_DIR}")
 set(_ANDROID_TOOL_NDK_TOOLCHAIN_VERSION "${_ANDROID_TOOL_VERS_NDK}")
 
 # _ANDROID_TOOL_PREFIX should now match `gcc -dumpmachine`.
 string(REGEX REPLACE "-$" "" _ANDROID_TOOL_C_TOOLCHAIN_MACHINE "${_ANDROID_TOOL_PREFIX}")
 
 set(_ANDROID_TOOL_C_TOOLCHAIN_VERSION "${_ANDROID_TOOL_VERS}")
-set(_ANDROID_TOOL_C_TOOLCHAIN_PREFIX "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_NAME}/prebuilt/${_ANDROID_HOST_DIR}/bin/${_ANDROID_TOOL_PREFIX}")
+set(_ANDROID_TOOL_C_TOOLCHAIN_PREFIX "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_NAME}/prebuilt/${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG}/bin/${_ANDROID_TOOL_PREFIX}")
 set(_ANDROID_TOOL_C_TOOLCHAIN_SUFFIX "${_ANDROID_HOST_EXT}")
 
 set(_ANDROID_TOOL_CXX_TOOLCHAIN_MACHINE "${_ANDROID_TOOL_C_TOOLCHAIN_MACHINE}")
@@ -238,9 +214,9 @@ set(_ANDROID_TOOL_CXX_TOOLCHAIN_SUFFIX "${_ANDROID_TOOL_C_TOOLCHAIN_SUFFIX}")
 
 if(_ANDROID_TOOL_CLANG_NAME)
   message(STATUS "Android: Selected Clang toolchain '${_ANDROID_TOOL_CLANG_NAME}' with GCC toolchain '${_ANDROID_TOOL_NAME}'")
-  set(_ANDROID_TOOL_C_COMPILER "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_LLVM_NAME}/prebuilt/${_ANDROID_HOST_DIR}/bin/clang${_ANDROID_HOST_EXT}")
-  set(_ANDROID_TOOL_C_COMPILER_EXTERNAL_TOOLCHAIN ${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_NAME}/prebuilt/${_ANDROID_HOST_DIR})
-  set(_ANDROID_TOOL_CXX_COMPILER "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_LLVM_NAME}/prebuilt/${_ANDROID_HOST_DIR}/bin/clang++${_ANDROID_HOST_EXT}")
+  set(_ANDROID_TOOL_C_COMPILER "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_LLVM_NAME}/prebuilt/${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG}/bin/clang${_ANDROID_HOST_EXT}")
+  set(_ANDROID_TOOL_C_COMPILER_EXTERNAL_TOOLCHAIN ${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_NAME}/prebuilt/${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG})
+  set(_ANDROID_TOOL_CXX_COMPILER "${CMAKE_ANDROID_NDK}/toolchains/${_ANDROID_TOOL_LLVM_NAME}/prebuilt/${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG}/bin/clang++${_ANDROID_HOST_EXT}")
   set(_ANDROID_TOOL_CXX_COMPILER_EXTERNAL_TOOLCHAIN "${_ANDROID_TOOL_C_COMPILER_EXTERNAL_TOOLCHAIN}")
 else()
   message(STATUS "Android: Selected GCC toolchain '${_ANDROID_TOOL_NAME}'")
@@ -267,4 +243,3 @@ unset(_ANDROID_TOOL_PREFIX)
 unset(_ANDROID_TOOL_CLANG_NAME)
 unset(_ANDROID_TOOL_CLANG_VERS)
 unset(_ANDROID_TOOL_LLVM_NAME)
-unset(_ANDROID_HOST_DIR)

Modules/Platform/Android/Determine-Compiler-Standalone.cmake

@@ -62,5 +62,4 @@ else()
   set(_ANDROID_TOOL_CXX_COMPILER_EXTERNAL_TOOLCHAIN "")
 endif()
 
-set(_ANDROID_TOOL_NDK_TOOLCHAIN_HOST_TAG "")
 set(_ANDROID_TOOL_NDK_TOOLCHAIN_VERSION "")

Modules/Platform/Android/Determine-Compiler.cmake

@@ -40,7 +40,6 @@ if(CMAKE_ANDROID_NDK)
 elseif(CMAKE_ANDROID_STANDALONE_TOOLCHAIN)
   include(Platform/Android/Determine-Compiler-Standalone)
 else()
-  set(_ANDROID_TOOL_NDK_TOOLCHAIN_HOST_TAG "")
   set(_ANDROID_TOOL_NDK_TOOLCHAIN_VERSION "")
   set(_ANDROID_TOOL_C_COMPILER "")
   set(_ANDROID_TOOL_C_TOOLCHAIN_MACHINE "")
@@ -65,7 +64,6 @@ macro(__android_determine_compiler lang)
 
     # Save the Android-specific information in CMake${lang}Compiler.cmake.
     set(CMAKE_${lang}_COMPILER_CUSTOM_CODE "
-set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG \"${_ANDROID_TOOL_NDK_TOOLCHAIN_HOST_TAG}\")
 set(CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION \"${_ANDROID_TOOL_NDK_TOOLCHAIN_VERSION}\")
 set(CMAKE_${lang}_ANDROID_TOOLCHAIN_MACHINE \"${_ANDROID_TOOL_${lang}_TOOLCHAIN_MACHINE}\")
 set(CMAKE_${lang}_ANDROID_TOOLCHAIN_VERSION \"${_ANDROID_TOOL_${lang}_TOOLCHAIN_VERSION}\")