Merge topic 'android-ndk-r19'

97bca2f9fa Android: Use unified toolchain in NDK r19+
19f36c5fb2 Android: Update test to not require GCC compiler to exist in NDK
f3e32ddae9 Android: Re-order system initialization to select sysroot last
9a0720b819 Android: Clarify name of internal variable for arch triple
4e6c58d937 Android: Select NDK host tag while determining system

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !3612

21 files changed, 171 insertions, 82 deletions

diff --git a/Help/manual/cmake-toolchains.7.rst b/Help/manual/cmake-toolchains.7.rst
index 7435d9a..f233d08 100644
--- a/Help/manual/cmake-toolchains.7.rst
+++ b/Help/manual/cmake-toolchains.7.rst
@@ -399,8 +399,10 @@ Configure use of an Android NDK with the following variables:
   be false unless using a NDK that does not provide unified headers.
 
 :variable:`CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION`
-  Set to the version of the NDK toolchain to be selected as the compiler.
-  If not specified, the default will be the latest available GCC toolchain.
+  On NDK r19 or above, this variable must be unset or set to ``clang``.
+  On NDK r18 or below, set this to the version of the NDK toolchain to
+  be selected as the compiler.  If not specified, the default will be
+  the latest available GCC toolchain.
 
 :variable:`CMAKE_ANDROID_STL_TYPE`
   Set to specify which C++ standard library to use.  If not specified,
diff --git a/Help/variable/CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION.rst b/Help/variable/CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION.rst
index 5ae55d1..22808e3 100644
--- a/Help/variable/CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION.rst
+++ b/Help/variable/CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION.rst
@@ -3,7 +3,11 @@ CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION
 
 When :ref:`Cross Compiling for Android with the NDK`, this variable
 may be set to specify the version of the toolchain to be used
-as the compiler.  The variable must be set to one of these forms:
+as the compiler.
+
+On NDK r19 or above, this variable must be unset or set to ``clang``.
+
+On NDK r18 or below, this variable must be set to one of these forms:
 
 * ``<major>.<minor>``: GCC of specified version
 * ``clang<major>.<minor>``: Clang of specified version
diff --git a/Modules/Platform/Android-Clang.cmake b/Modules/Platform/Android-Clang.cmake
index 9ed1e01..847178f 100644
--- a/Modules/Platform/Android-Clang.cmake
+++ b/Modules/Platform/Android-Clang.cmake
@@ -40,6 +40,9 @@ macro(__android_compiler_clang lang)
   endif()
   if(NOT CMAKE_${lang}_COMPILER_TARGET)
     set(CMAKE_${lang}_COMPILER_TARGET "${_ANDROID_ABI_CLANG_TARGET}")
+    if(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
+      string(APPEND CMAKE_${lang}_COMPILER_TARGET "${CMAKE_SYSTEM_VERSION}")
+    endif()
     list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "--target=${CMAKE_${lang}_COMPILER_TARGET}")
   endif()
 endmacro()
diff --git a/Modules/Platform/Android-Common.cmake b/Modules/Platform/Android-Common.cmake
index f8b9346..1affcd0 100644
--- a/Modules/Platform/Android-Common.cmake
+++ b/Modules/Platform/Android-Common.cmake
@@ -47,7 +47,41 @@ if(CMAKE_ANDROID_NDK)
 endif()
 
 if(CMAKE_ANDROID_STL_TYPE)
-  if(CMAKE_ANDROID_NDK)
+  if(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
+    if(CMAKE_ANDROID_STL_TYPE STREQUAL "system")
+      set(_ANDROID_STL_EXCEPTIONS 0)
+      set(_ANDROID_STL_RTTI 0)
+      macro(__android_stl lang)
+        string(APPEND CMAKE_${lang}_FLAGS_INIT " -stdlib=libstdc++")
+      endmacro()
+    elseif(CMAKE_ANDROID_STL_TYPE STREQUAL "c++_static")
+      set(_ANDROID_STL_EXCEPTIONS 1)
+      set(_ANDROID_STL_RTTI 1)
+      macro(__android_stl lang)
+        string(APPEND CMAKE_${lang}_FLAGS_INIT " -stdlib=libc++")
+        string(APPEND CMAKE_${lang}_STANDARD_LIBRARIES " -static-libstdc++")
+      endmacro()
+    elseif(CMAKE_ANDROID_STL_TYPE STREQUAL "c++_shared")
+      set(_ANDROID_STL_EXCEPTIONS 1)
+      set(_ANDROID_STL_RTTI 1)
+      macro(__android_stl lang)
+        string(APPEND CMAKE_${lang}_FLAGS_INIT " -stdlib=libc++")
+      endmacro()
+    elseif(CMAKE_ANDROID_STL_TYPE STREQUAL "none")
+      set(_ANDROID_STL_RTTI 0)
+      set(_ANDROID_STL_EXCEPTIONS 0)
+      macro(__android_stl lang)
+        # FIXME: Add a way to add project-wide language-specific compile-only flags.
+        set(CMAKE_CXX_COMPILE_OBJECT
+          "<CMAKE_CXX_COMPILER>  <DEFINES> <INCLUDES> <FLAGS> -o <OBJECT> -c <SOURCE> -nostdinc++")
+        string(APPEND CMAKE_${lang}_STANDARD_LIBRARIES " -nostdlib++")
+      endmacro()
+    else()
+      message(FATAL_ERROR
+        "Android: STL '${CMAKE_ANDROID_STL_TYPE}' not supported by this NDK."
+        )
+    endif()
+  elseif(CMAKE_ANDROID_NDK)
 
     macro(__android_stl_inc lang dir req)
       if(EXISTS "${dir}")
@@ -152,6 +186,10 @@ macro(__android_compiler_common lang)
     __android_stl(CXX)
   endif()
 
+  if(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
+    string(APPEND CMAKE_${lang}_STANDARD_LIBRARIES " -latomic -lm")
+  endif()
+
   # <ndk>/build/core/definitions.mk appends the sysroot's include directory
   # explicitly at the end of the command-line include path so that it
   # precedes the toolchain's builtin include directories.  This is
@@ -161,7 +199,7 @@ macro(__android_compiler_common lang)
   #
   # Do not do this for a standalone toolchain because it is already
   # tied to a specific API version.
-  if(CMAKE_ANDROID_NDK)
+  if(CMAKE_ANDROID_NDK AND NOT CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
     if(CMAKE_SYSROOT_COMPILE)
       set(_cmake_sysroot_compile "${CMAKE_SYSROOT_COMPILE}")
     else()
@@ -170,7 +208,7 @@ macro(__android_compiler_common lang)
     if(NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
       list(APPEND CMAKE_${lang}_STANDARD_INCLUDE_DIRECTORIES
         "${_cmake_sysroot_compile}/usr/include"
-        "${_cmake_sysroot_compile}/usr/include/${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}"
+        "${_cmake_sysroot_compile}/usr/include/${CMAKE_ANDROID_ARCH_TRIPLE}"
         )
     else()
       list(APPEND CMAKE_${lang}_STANDARD_INCLUDE_DIRECTORIES "${_cmake_sysroot_compile}/usr/include")
diff --git a/Modules/Platform/Android-Determine.cmake b/Modules/Platform/Android-Determine.cmake
index bb42eed..e7c1b48 100644
--- a/Modules/Platform/Android-Determine.cmake
+++ b/Modules/Platform/Android-Determine.cmake
@@ -198,32 +198,66 @@ 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 '${CMAKE_HOST_SYSTEM_NAME}' not supported.")
+  endif()
+
+  # Look for a unified toolchain/sysroot provided with the NDK.
+  set(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED "${CMAKE_ANDROID_NDK}/toolchains/llvm/prebuilt/${CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG}")
+  if(NOT IS_DIRECTORY "${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}/sysroot")
+    set(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED "")
+  endif()
+else()
+  set(CMAKE_ANDROID_NDK_TOOLCHAIN_HOST_TAG "")
+  set(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED "")
+endif()
+
 # https://developer.android.com/ndk/guides/abis.html
 
 set(_ANDROID_ABI_arm64-v8a_PROC     "aarch64")
 set(_ANDROID_ABI_arm64-v8a_ARCH     "arm64")
-set(_ANDROID_ABI_arm64-v8a_HEADER   "aarch64-linux-android")
+set(_ANDROID_ABI_arm64-v8a_TRIPLE   "aarch64-linux-android")
 set(_ANDROID_ABI_armeabi-v7a_PROC   "armv7-a")
 set(_ANDROID_ABI_armeabi-v7a_ARCH   "arm")
-set(_ANDROID_ABI_armeabi-v7a_HEADER "arm-linux-androideabi")
+set(_ANDROID_ABI_armeabi-v7a_TRIPLE "arm-linux-androideabi")
 set(_ANDROID_ABI_armeabi-v6_PROC    "armv6")
 set(_ANDROID_ABI_armeabi-v6_ARCH    "arm")
-set(_ANDROID_ABI_armeabi-v6_HEADER  "arm-linux-androideabi")
+set(_ANDROID_ABI_armeabi-v6_TRIPLE  "arm-linux-androideabi")
 set(_ANDROID_ABI_armeabi_PROC       "armv5te")
 set(_ANDROID_ABI_armeabi_ARCH       "arm")
-set(_ANDROID_ABI_armeabi_HEADER     "arm-linux-androideabi")
+set(_ANDROID_ABI_armeabi_TRIPLE     "arm-linux-androideabi")
 set(_ANDROID_ABI_mips_PROC          "mips")
 set(_ANDROID_ABI_mips_ARCH          "mips")
-set(_ANDROID_ABI_mips_HEADER        "mipsel-linux-android")
+set(_ANDROID_ABI_mips_TRIPLE        "mipsel-linux-android")
 set(_ANDROID_ABI_mips64_PROC        "mips64")
 set(_ANDROID_ABI_mips64_ARCH        "mips64")
-set(_ANDROID_ABI_mips64_HEADER      "mips64el-linux-android")
+set(_ANDROID_ABI_mips64_TRIPLE      "mips64el-linux-android")
 set(_ANDROID_ABI_x86_PROC           "i686")
 set(_ANDROID_ABI_x86_ARCH           "x86")
-set(_ANDROID_ABI_x86_HEADER         "i686-linux-android")
+set(_ANDROID_ABI_x86_TRIPLE         "i686-linux-android")
 set(_ANDROID_ABI_x86_64_PROC        "x86_64")
 set(_ANDROID_ABI_x86_64_ARCH        "x86_64")
-set(_ANDROID_ABI_x86_64_HEADER      "x86_64-linux-android")
+set(_ANDROID_ABI_x86_64_TRIPLE      "x86_64-linux-android")
 
 set(_ANDROID_PROC_aarch64_ARCH_ABI "arm64-v8a")
 set(_ANDROID_PROC_armv7-a_ARCH_ABI "armeabi-v7a")
@@ -308,7 +342,7 @@ if(_ANDROID_SYSROOT_ARCH AND NOT "x${_ANDROID_SYSROOT_ARCH}" STREQUAL "x${CMAKE_
     "does not match architecture '${CMAKE_ANDROID_ARCH}' for the ABI '${CMAKE_ANDROID_ARCH_ABI}'."
     )
 endif()
-set(CMAKE_ANDROID_ARCH_HEADER_TRIPLE "${_ANDROID_ABI_${CMAKE_ANDROID_ARCH_ABI}_HEADER}")
+set(CMAKE_ANDROID_ARCH_TRIPLE "${_ANDROID_ABI_${CMAKE_ANDROID_ARCH_ABI}_TRIPLE}")
 
 # Select a processor.
 if(NOT CMAKE_SYSTEM_PROCESSOR)
@@ -321,7 +355,7 @@ if(NOT _ANDROID_ABI_${CMAKE_ANDROID_ARCH_ABI}_PROC STREQUAL CMAKE_SYSTEM_PROCESS
 endif()
 
 if(CMAKE_ANDROID_NDK AND NOT DEFINED CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
-  if(IS_DIRECTORY "${CMAKE_ANDROID_NDK}/sysroot/usr/include/${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}")
+  if(IS_DIRECTORY "${CMAKE_ANDROID_NDK}/sysroot/usr/include/${CMAKE_ANDROID_ARCH_TRIPLE}")
     # Unified headers exist so we use them by default.
     set(CMAKE_ANDROID_NDK_DEPRECATED_HEADERS 0)
   else()
@@ -340,8 +374,10 @@ set(CMAKE_ANDROID_ARCH_ABI \"${CMAKE_ANDROID_ARCH_ABI}\")
 
 if(CMAKE_ANDROID_NDK)
   string(APPEND CMAKE_SYSTEM_CUSTOM_CODE
-    "set(CMAKE_ANDROID_ARCH_HEADER_TRIPLE \"${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}\")\n"
+    "set(CMAKE_ANDROID_ARCH_TRIPLE \"${CMAKE_ANDROID_ARCH_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"
+    "set(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED \"${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}\")\n"
     )
 endif()
 
diff --git a/Modules/Platform/Android-Initialize.cmake b/Modules/Platform/Android-Initialize.cmake
index a434f90..a5d2820 100644
--- a/Modules/Platform/Android-Initialize.cmake
+++ b/Modules/Platform/Android-Initialize.cmake
@@ -17,6 +17,13 @@ if(CMAKE_SYSTEM_VERSION EQUAL 1)
   return()
 endif()
 
+set(CMAKE_BUILD_TYPE_INIT Debug)
+
+# Skip sysroot selection if the NDK has a unified toolchain.
+if(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
+  return()
+endif()
+
 if(NOT CMAKE_SYSROOT)
   if(CMAKE_ANDROID_NDK)
     set(CMAKE_SYSROOT "${CMAKE_ANDROID_NDK}/platforms/android-${CMAKE_SYSTEM_VERSION}/arch-${CMAKE_ANDROID_ARCH}")
@@ -40,5 +47,3 @@ else()
     "Android: No CMAKE_SYSROOT was selected."
     )
 endif()
-
-set(CMAKE_BUILD_TYPE_INIT Debug)
diff --git a/Modules/Platform/Android/Determine-Compiler-NDK.cmake b/Modules/Platform/Android/Determine-Compiler-NDK.cmake
index 5f2cc52..e009c10 100644
--- a/Modules/Platform/Android/Determine-Compiler-NDK.cmake
+++ b/Modules/Platform/Android/Determine-Compiler-NDK.cmake
@@ -1,6 +1,31 @@
 # Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
 # file Copyright.txt or https://cmake.org/licensing for details.
 
+# In Android NDK r19 and above there is a single clang toolchain.
+if(CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED)
+  if(CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION AND NOT CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION STREQUAL "clang")
+    message(FATAL_ERROR
+      "Android: The CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION value '${CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION}' "
+      "is not supported by this NDK.  It must be 'clang' or not set at all."
+      )
+  endif()
+  message(STATUS "Android: Selected unified Clang toolchain")
+  set(_ANDROID_TOOL_NDK_TOOLCHAIN_VERSION "clang")
+  set(_ANDROID_TOOL_C_COMPILER "${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}/bin/clang${_ANDROID_HOST_EXT}")
+  set(_ANDROID_TOOL_C_TOOLCHAIN_MACHINE "${CMAKE_ANDROID_ARCH_TRIPLE}")
+  set(_ANDROID_TOOL_C_TOOLCHAIN_VERSION "")
+  set(_ANDROID_TOOL_C_COMPILER_EXTERNAL_TOOLCHAIN "")
+  set(_ANDROID_TOOL_C_TOOLCHAIN_PREFIX "${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}/bin/${CMAKE_ANDROID_ARCH_TRIPLE}-")
+  set(_ANDROID_TOOL_C_TOOLCHAIN_SUFFIX "${_ANDROID_HOST_EXT}")
+  set(_ANDROID_TOOL_CXX_COMPILER "${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}/bin/clang++${_ANDROID_HOST_EXT}")
+  set(_ANDROID_TOOL_CXX_TOOLCHAIN_MACHINE "${CMAKE_ANDROID_ARCH_TRIPLE}")
+  set(_ANDROID_TOOL_CXX_TOOLCHAIN_VERSION "")
+  set(_ANDROID_TOOL_CXX_COMPILER_EXTERNAL_TOOLCHAIN "")
+  set(_ANDROID_TOOL_CXX_TOOLCHAIN_PREFIX "${CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED}/bin/${CMAKE_ANDROID_ARCH_TRIPLE}-")
+  set(_ANDROID_TOOL_CXX_TOOLCHAIN_SUFFIX "${_ANDROID_HOST_EXT}")
+  return()
+endif()
+
 # In Android NDK releases there is build system toolchain selection logic in
 # these files:
 #
@@ -195,40 +220,16 @@ if(NOT _ANDROID_TOOL_PREFIX AND "${_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 "${_ANDROID_TOOL_C_TOOLCHAIN_MACHINE}")
@@ -238,9 +239,9 @@ set(_ANDROID_TOOL_CXX_TOOLCHAIN_SUFFIX "${_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 +268,3 @@ unset(_ANDROID_TOOL_PREFIX)
 unset(_ANDROID_TOOL_CLANG_NAME)
 unset(_ANDROID_TOOL_CLANG_VERS)
 unset(_ANDROID_TOOL_LLVM_NAME)
-unset(_ANDROID_HOST_DIR)
diff --git a/Modules/Platform/Android/Determine-Compiler-Standalone.cmake b/Modules/Platform/Android/Determine-Compiler-Standalone.cmake
index 4c1ac1f..5095aff 100644
--- a/Modules/Platform/Android/Determine-Compiler-Standalone.cmake
+++ b/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 "")
diff --git a/Modules/Platform/Android/Determine-Compiler.cmake b/Modules/Platform/Android/Determine-Compiler.cmake
index a03ebcc..5c6b97b 100644
--- a/Modules/Platform/Android/Determine-Compiler.cmake
+++ b/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}\")
diff --git a/Modules/Platform/Android/abi-common.cmake b/Modules/Platform/Android/abi-common.cmake
index 6bce3c7..b01ef61 100644
--- a/Modules/Platform/Android/abi-common.cmake
+++ b/Modules/Platform/Android/abi-common.cmake
@@ -3,7 +3,7 @@ string(APPEND _ANDROID_ABI_INIT_CFLAGS
   " -no-canonical-prefixes"
   )
 
-if(CMAKE_ANDROID_NDK AND NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
+if(CMAKE_ANDROID_NDK AND NOT CMAKE_ANDROID_NDK_TOOLCHAIN_UNIFIED AND NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
   string(APPEND _ANDROID_ABI_INIT_CFLAGS " -D__ANDROID_API__=${CMAKE_SYSTEM_VERSION}")
 endif()
 
diff --git a/Tests/RunCMake/Android/common.cmake b/Tests/RunCMake/Android/common.cmake
index aaa7c89..d96ab86 100644
--- a/Tests/RunCMake/Android/common.cmake
+++ b/Tests/RunCMake/Android/common.cmake
@@ -6,8 +6,6 @@ if(NOT ANDROID)
 endif()
 
 foreach(f
-    "${CMAKE_C_ANDROID_TOOLCHAIN_PREFIX}gcc${CMAKE_C_ANDROID_TOOLCHAIN_SUFFIX}"
-    "${CMAKE_CXX_ANDROID_TOOLCHAIN_PREFIX}g++${CMAKE_CXX_ANDROID_TOOLCHAIN_SUFFIX}"
     "${CMAKE_CXX_ANDROID_TOOLCHAIN_PREFIX}ar${CMAKE_CXX_ANDROID_TOOLCHAIN_SUFFIX}"
     "${CMAKE_CXX_ANDROID_TOOLCHAIN_PREFIX}ld${CMAKE_CXX_ANDROID_TOOLCHAIN_SUFFIX}"
     )
@@ -51,23 +49,26 @@ elseif(CMAKE_ANDROID_STANDALONE_TOOLCHAIN)
   endif()
 endif()
 
-execute_process(
-  COMMAND "${CMAKE_C_ANDROID_TOOLCHAIN_PREFIX}gcc${CMAKE_C_ANDROID_TOOLCHAIN_SUFFIX}" -dumpmachine
-  OUTPUT_VARIABLE _out OUTPUT_STRIP_TRAILING_WHITESPACE
-  ERROR_VARIABLE _err
-  RESULT_VARIABLE _res
-  )
-if(NOT _res EQUAL 0)
-  message(SEND_ERROR "Failed to run 'gcc -dumpmachine':\n ${_res}")
-endif()
-string(REPLACE "--" "-" _out_check "${_out}")
-if(NOT _out_check STREQUAL "${CMAKE_C_ANDROID_TOOLCHAIN_MACHINE}"
-    AND NOT (_out STREQUAL "arm--linux-android" AND CMAKE_C_ANDROID_TOOLCHAIN_MACHINE STREQUAL "arm-linux-androideabi"))
-  message(SEND_ERROR "'gcc -dumpmachine' produced:\n"
-    " ${_out}\n"
-    "which does not match CMAKE_C_ANDROID_TOOLCHAIN_MACHINE:\n"
-    " ${CMAKE_C_ANDROID_TOOLCHAIN_MACHINE}"
+set(gcc ${CMAKE_C_ANDROID_TOOLCHAIN_PREFIX}gcc${CMAKE_C_ANDROID_TOOLCHAIN_SUFFIX})
+if(EXISTS "${gcc}")
+  execute_process(
+    COMMAND "${CMAKE_C_ANDROID_TOOLCHAIN_PREFIX}gcc${CMAKE_C_ANDROID_TOOLCHAIN_SUFFIX}" -dumpmachine
+    OUTPUT_VARIABLE _out OUTPUT_STRIP_TRAILING_WHITESPACE
+    ERROR_VARIABLE _err
+    RESULT_VARIABLE _res
     )
+  if(NOT _res EQUAL 0)
+    message(SEND_ERROR "Failed to run 'gcc -dumpmachine':\n ${_res}")
+  endif()
+  string(REPLACE "--" "-" _out_check "${_out}")
+  if(NOT _out_check STREQUAL "${CMAKE_C_ANDROID_TOOLCHAIN_MACHINE}"
+      AND NOT (_out STREQUAL "arm--linux-android" AND CMAKE_C_ANDROID_TOOLCHAIN_MACHINE STREQUAL "arm-linux-androideabi"))
+    message(SEND_ERROR "'gcc -dumpmachine' produced:\n"
+      " ${_out}\n"
+      "which does not match CMAKE_C_ANDROID_TOOLCHAIN_MACHINE:\n"
+      " ${CMAKE_C_ANDROID_TOOLCHAIN_MACHINE}"
+      )
+  endif()
 endif()
 
 if(CMAKE_ANDROID_STL_TYPE STREQUAL "none")
diff --git a/Tests/RunCMake/Android/ndk-arm64-v8a-stdout.txt b/Tests/RunCMake/Android/ndk-arm64-v8a-stdout.txt
index 8d0bdc2..a228ccc 100644
--- a/Tests/RunCMake/Android/ndk-arm64-v8a-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-arm64-v8a-stdout.txt
@@ -1,2 +1,2 @@
 -- Android: Targeting API '[0-9]+' with architecture 'arm64', ABI 'arm64-v8a', and processor 'aarch64'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
diff --git a/Tests/RunCMake/Android/ndk-armeabi-arm-stdout.txt b/Tests/RunCMake/Android/ndk-armeabi-arm-stdout.txt
index 3741da3..72ec00e 100644
--- a/Tests/RunCMake/Android/ndk-armeabi-arm-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-armeabi-arm-stdout.txt
@@ -1,3 +1,3 @@
 -- Android: Targeting API '[0-9]+' with architecture 'arm', ABI 'armeabi', and processor 'armv5te'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
 .*-- CMAKE_ANDROID_ARM_MODE=1
diff --git a/Tests/RunCMake/Android/ndk-armeabi-v7a-neon-stdout.txt b/Tests/RunCMake/Android/ndk-armeabi-v7a-neon-stdout.txt
index ac2bfd5..8bd87fa 100644
--- a/Tests/RunCMake/Android/ndk-armeabi-v7a-neon-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-armeabi-v7a-neon-stdout.txt
@@ -1,3 +1,3 @@
 -- Android: Targeting API '[0-9]+' with architecture 'arm', ABI 'armeabi-v7a', and processor 'armv7-a'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
 .*-- CMAKE_ANDROID_ARM_NEON=1
diff --git a/Tests/RunCMake/Android/ndk-armeabi-v7a-stdout.txt b/Tests/RunCMake/Android/ndk-armeabi-v7a-stdout.txt
index 0edb4f7..554548e 100644
--- a/Tests/RunCMake/Android/ndk-armeabi-v7a-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-armeabi-v7a-stdout.txt
@@ -1,3 +1,3 @@
 -- Android: Targeting API '[0-9]+' with architecture 'arm', ABI 'armeabi-v7a', and processor 'armv7-a'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
 .*-- CMAKE_ANDROID_ARM_NEON=0
diff --git a/Tests/RunCMake/Android/ndk-badver-stderr.txt b/Tests/RunCMake/Android/ndk-badver-stderr.txt
index df2c5e6..ce6bc4e 100644
--- a/Tests/RunCMake/Android/ndk-badver-stderr.txt
+++ b/Tests/RunCMake/Android/ndk-badver-stderr.txt
@@ -1,11 +1,12 @@
 ^CMake Error at .*/Modules/Platform/Android/Determine-Compiler-NDK.cmake:[0-9]+ \(message\):
-  Android: The CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION value 'badver' is not one
+  Android: The CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION value 'badver' is not(
+  supported by this NDK.  It must be 'clang' or not set at all\.| one
   of the allowed forms:
 
     <major>.<minor>       = GCC of specified version
     clang<major>.<minor>  = Clang of specified version
     clang                 = Clang of most recent available version
-
+)
 Call Stack \(most recent call first\):
 .*
   ndk-badver.cmake:1 \(enable_language\)
diff --git a/Tests/RunCMake/Android/ndk-badvernum-stderr.txt b/Tests/RunCMake/Android/ndk-badvernum-stderr.txt
index adacaf1..aec91d9 100644
--- a/Tests/RunCMake/Android/ndk-badvernum-stderr.txt
+++ b/Tests/RunCMake/Android/ndk-badvernum-stderr.txt
@@ -1,4 +1,6 @@
-^CMake Error at .*/Modules/Platform/Android/Determine-Compiler-NDK.cmake:[0-9]+ \(message\):
+^CMake Error at .*/Modules/Platform/Android/Determine-Compiler-NDK.cmake:[0-9]+ \(message\):(
+  Android: The CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION value '1.0' is not
+  supported by this NDK.  It must be 'clang' or not set at all.|
   Android: No toolchain for ABI 'armeabi(-v7a)?' found in the NDK:
 
     .*
@@ -6,7 +8,7 @@
   of the version specified by CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION:
 
     1\.0
-
+)
 Call Stack \(most recent call first\):
 .*
   ndk-badvernum.cmake:1 \(enable_language\)
diff --git a/Tests/RunCMake/Android/ndk-mips-stdout.txt b/Tests/RunCMake/Android/ndk-mips-stdout.txt
index c744683..8ce544d 100644
--- a/Tests/RunCMake/Android/ndk-mips-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-mips-stdout.txt
@@ -1,2 +1,2 @@
 -- Android: Targeting API '[0-9]+' with architecture 'mips', ABI 'mips', and processor 'mips'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
diff --git a/Tests/RunCMake/Android/ndk-mips64-stdout.txt b/Tests/RunCMake/Android/ndk-mips64-stdout.txt
index 839ddfd..1d7edea 100644
--- a/Tests/RunCMake/Android/ndk-mips64-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-mips64-stdout.txt
@@ -1,2 +1,2 @@
 -- Android: Targeting API '[0-9]+' with architecture 'mips64', ABI 'mips64', and processor 'mips64'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
diff --git a/Tests/RunCMake/Android/ndk-x86-stdout.txt b/Tests/RunCMake/Android/ndk-x86-stdout.txt
index 2dbb2f0..8d710fe 100644
--- a/Tests/RunCMake/Android/ndk-x86-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-x86-stdout.txt
@@ -1,2 +1,2 @@
 -- Android: Targeting API '[0-9]+' with architecture 'x86', ABI 'x86', and processor 'i686'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')
diff --git a/Tests/RunCMake/Android/ndk-x86_64-stdout.txt b/Tests/RunCMake/Android/ndk-x86_64-stdout.txt
index a7ae91d..695a088 100644
--- a/Tests/RunCMake/Android/ndk-x86_64-stdout.txt
+++ b/Tests/RunCMake/Android/ndk-x86_64-stdout.txt
@@ -1,2 +1,2 @@
 -- Android: Targeting API '[0-9]+' with architecture 'x86_64', ABI 'x86_64', and processor 'x86_64'
--- Android: Selected (Clang toolchain '[^']+' with )?GCC toolchain '[^']+'
+-- Android: Selected (unified Clang toolchain|(Clang toolchain '[^']+' with )?GCC toolchain '[^']+')