Missing library #include <features.h>

[gerardogc2378]

Compiling urho sharp for Android I have this output:

/home/ggc/android_home/ndk-bundle/sources/cxx-stl/llvm-libc++/include/__config:169:22: fatal error: features.h: No such file or directory
 #include <features.h>

Environment Details

Not all of these will be relevant to every bug, but please provide as much
information as you can.

• NDK Version: Value from Pkg.Revision in ndk-bundle/source.properties. If not
  the latest version, check there before filing.
• Build sytem: ndk-build? cmake? standalone toolchain? custom? (if gradle, file
  a bug against studio as specified above)
• Host OS: ArchLinux
• Compiler: clang from ndk latest using sdkmanager to install
• NDK API level: ndk-bundle | 16.1.4479499 | NDK | ndk-bundle

[rprichard]

The NDK has a sysroot/usr/include/features.h file that would normally be included, so apparently it's not on your include search path. You're probably not specifying the --sysroot option correctly.

The compiler command-line would be useful information to add to this report.

I searched for urho and found a Makefile that hasn't been updated for the NDK's unified headers, so maybe that's the problem.

From https://android.googlesource.com/platform/ndk/+/ndk-release-r16/docs/UnifiedHeaders.md:

The compile time sysroot is now $NDK/sysroot. Previously this was $NDK/platforms/android-$API/arch-$ARCH.

Pass -isystem $NDK/sysroot/usr/include/$TRIPLE when compiling. The triple has the following mapping:

From https://github.com/xamarin/urho/blob/1cb035b0f4d742a340167c21cdeae39b1fb547a6/MakeAndroid:

C_FLAGS=-fexceptions -fPIC --sysroot=$(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM) -funwind-tables -funswitch-loops -finline-limit=300 -fsigned-char -no-canonical-prefixes -fdata-sections -ffunction-sections -Wa,--noexecstack -fstack-protector -fomit-frame-pointer -fstrict-aliasing -O3 -DNDEBUG -isystem $(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM)/usr/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/libs/$(ABI)/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/include/backward -I$(URHO3D_ANDROID_DIR)/include -I$(URHO3D_ANDROID_DIR)/include/Urho3D/ThirdParty -I$(URHO3D_ANDROID_DIR)/include/Urho3D/ThirdParty/Bullet -I$(URHO3D_SRC_DIR)/Source/Samples

CXX_FLAGS = --sysroot=$(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM) $(ABI_FLAGS) -fpermissive -fsigned-char -funwind-tables -no-canonical-prefixes -Wa,--noexecstack -Wformat -Werror=format-security -fdata-sections -ffunction-sections -frtti -funswitch-loops -finline-limit=300 -fstack-protector -fomit-frame-pointer -fstrict-aliasing -fexceptions -std=gnu++11 -Wno-invalid-offsetof -O3 -DNDEBUG -fPIC -isystem $(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM)/usr/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/libs/$(ABI)/include -isystem $(ANDK_DIR)/sources/cxx-stl/gnu-libstdc++/$(TOOLCHAINS_VER)/include/backward

The Makefile is also using g++, gnustl, and armeabi (obsolete, use armeabi-v7a instead).

These flags need updating for unified headers:

• --sysroot=$(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM)
• -isystem $(ANDK_DIR)/platforms/$(ANDROID_API)/arch-$(PLATFORM)/usr/include

You'd probably want:

• --sysroot=$(ANDK_DIR)/sysroot
• -isystem $(ANDK_DIR)/sysroot/usr/include/arm-linux-androideabi

I doubt there's an NDK bug here.

[gerardogc2378]

I have the same issue with this file https://github.com/urho3d/Urho3D/blob/master/CMake/Toolchains/Android.cmake (Urho3D Game Engine) maybe it needs some changes like you said, these are obsolete makefiles and need upgrade...

[rprichard]

As @weitjong said in urho3d/urho3d#2311 (comment), the Urho3D build system needs to be updated for NDK r16. I think this issue can be closed in favor of the Urho3D issue.