Android: Add support for unified headers

The unified headers are preferred as of NDK r15, so use them by default
if available and provide an option to use the deprecated headers.

Inspired-by: Florent Castelli <florent.castelli@gmail.com>
Fixes: #16584

4 files changed, 52 insertions, 16 deletions

diff --git a/Modules/Platform/Android-Common.cmake b/Modules/Platform/Android-Common.cmake
index 78938dc..ac72676 100644
--- a/Modules/Platform/Android-Common.cmake
+++ b/Modules/Platform/Android-Common.cmake
@@ -161,6 +161,9 @@ macro(__android_compiler_common lang)
   # tied to a specific API version.
   if(CMAKE_ANDROID_NDK)
     list(APPEND CMAKE_${lang}_STANDARD_INCLUDE_DIRECTORIES "${CMAKE_SYSROOT}/usr/include")
+    if(NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
+      list(APPEND CMAKE_${lang}_STANDARD_INCLUDE_DIRECTORIES "${CMAKE_SYSROOT}/usr/include/${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}")
+    endif()
     list(REMOVE_ITEM CMAKE_${lang}_IMPLICIT_INCLUDE_DIRECTORIES "/usr/include")
   endif()
 endmacro()
diff --git a/Modules/Platform/Android-Determine.cmake b/Modules/Platform/Android-Determine.cmake
index 076be85..add1dc1 100644
--- a/Modules/Platform/Android-Determine.cmake
+++ b/Modules/Platform/Android-Determine.cmake
@@ -197,22 +197,30 @@ 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_armeabi-v7a_PROC "armv7-a")
-set(_ANDROID_ABI_armeabi-v7a_ARCH "arm")
-set(_ANDROID_ABI_armeabi-v6_PROC  "armv6")
-set(_ANDROID_ABI_armeabi-v6_ARCH  "arm")
-set(_ANDROID_ABI_armeabi_PROC     "armv5te")
-set(_ANDROID_ABI_armeabi_ARCH     "arm")
-set(_ANDROID_ABI_mips_PROC        "mips")
-set(_ANDROID_ABI_mips_ARCH        "mips")
-set(_ANDROID_ABI_mips64_PROC      "mips64")
-set(_ANDROID_ABI_mips64_ARCH      "mips64")
-set(_ANDROID_ABI_x86_PROC         "i686")
-set(_ANDROID_ABI_x86_ARCH         "x86")
-set(_ANDROID_ABI_x86_64_PROC      "x86_64")
-set(_ANDROID_ABI_x86_64_ARCH      "x86_64")
+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_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-v6_PROC    "armv6")
+set(_ANDROID_ABI_armeabi-v6_ARCH    "arm")
+set(_ANDROID_ABI_armeabi-v6_HEADER  "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_mips_PROC          "mips")
+set(_ANDROID_ABI_mips_ARCH          "mips")
+set(_ANDROID_ABI_mips_HEADER        "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_x86_PROC           "i686")
+set(_ANDROID_ABI_x86_ARCH           "x86")
+set(_ANDROID_ABI_x86_HEADER         "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_PROC_aarch64_ARCH_ABI "arm64-v8a")
 set(_ANDROID_PROC_armv7-a_ARCH_ABI "armeabi-v7a")
@@ -264,6 +272,7 @@ 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}")
 
 # Select a processor.
 if(NOT CMAKE_SYSTEM_PROCESSOR)
@@ -275,6 +284,16 @@ if(NOT _ANDROID_ABI_${CMAKE_ANDROID_ARCH_ABI}_PROC STREQUAL CMAKE_SYSTEM_PROCESS
   message(FATAL_ERROR "Android: The specified CMAKE_ANDROID_ARCH_ABI='${CMAKE_ANDROID_ARCH_ABI}' and CMAKE_SYSTEM_PROCESSOR='${CMAKE_SYSTEM_PROCESSOR}' is not a valid combination.")
 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}")
+    # Unified headers exist so we use them by default.
+    set(CMAKE_ANDROID_NDK_DEPRECATED_HEADERS 0)
+  else()
+    # Unified headers do not exist so use the deprecated headers.
+    set(CMAKE_ANDROID_NDK_DEPRECATED_HEADERS 1)
+  endif()
+endif()
+
 # Save the Android-specific information in CMakeSystem.cmake.
 set(CMAKE_SYSTEM_CUSTOM_CODE "
 set(CMAKE_ANDROID_NDK \"${CMAKE_ANDROID_NDK}\")
@@ -283,6 +302,13 @@ set(CMAKE_ANDROID_ARCH \"${CMAKE_ANDROID_ARCH}\")
 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 \"${CMAKE_ANDROID_ARCH_HEADER_TRIPLE}\")\n"
+    "set(CMAKE_ANDROID_NDK_DEPRECATED_HEADERS \"${CMAKE_ANDROID_NDK_DEPRECATED_HEADERS}\")\n"
+    )
+endif()
+
 # Select an ARM variant.
 if(CMAKE_ANDROID_ARCH_ABI MATCHES "^armeabi")
   if(CMAKE_ANDROID_ARM_MODE)
diff --git a/Modules/Platform/Android-Initialize.cmake b/Modules/Platform/Android-Initialize.cmake
index a327223..a434f90 100644
--- a/Modules/Platform/Android-Initialize.cmake
+++ b/Modules/Platform/Android-Initialize.cmake
@@ -20,6 +20,9 @@ endif()
 if(NOT CMAKE_SYSROOT)
   if(CMAKE_ANDROID_NDK)
     set(CMAKE_SYSROOT "${CMAKE_ANDROID_NDK}/platforms/android-${CMAKE_SYSTEM_VERSION}/arch-${CMAKE_ANDROID_ARCH}")
+    if(NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
+      set(CMAKE_SYSROOT_COMPILE "${CMAKE_ANDROID_NDK}/sysroot")
+    endif()
   elseif(CMAKE_ANDROID_STANDALONE_TOOLCHAIN)
     set(CMAKE_SYSROOT "${CMAKE_ANDROID_STANDALONE_TOOLCHAIN}/sysroot")
   endif()
diff --git a/Modules/Platform/Android/abi-common.cmake b/Modules/Platform/Android/abi-common.cmake
index 3b0eb01..10fb897 100644
--- a/Modules/Platform/Android/abi-common.cmake
+++ b/Modules/Platform/Android/abi-common.cmake
@@ -3,6 +3,10 @@ string(APPEND _ANDROID_ABI_INIT_CFLAGS
   " -no-canonical-prefixes"
   )
 
+if(CMAKE_ANDROID_NDK AND NOT CMAKE_ANDROID_NDK_DEPRECATED_HEADERS)
+  string(APPEND _ANDROID_ABI_INIT_CFLAGS " -D__ANDROID_API__=${CMAKE_SYSTEM_VERSION}")
+endif()
+
 if(NOT DEFINED CMAKE_POSITION_INDEPENDENT_CODE
     AND NOT CMAKE_SYSTEM_VERSION VERSION_LESS 16)
   set(CMAKE_POSITION_INDEPENDENT_CODE ON)