[question] Detect NDK r19 or later. #1029

MikuAuahDark · 2019-06-29T03:39:23Z

I have an Android.mk which does work on NDK r18 and earlier but not when using NDK r19 due to conflicting functions.

Scenario: I have library that is compiled with ndk-build. The library itself is using autoconf/autotools/whatever you call it to generate config.h but since it's simple enough, I can create dummy config.h and define everything using LOCAL_C_FLAGS and write the Android.mk. Now the problem with NDK r19 is that it defines log2f regardless of API level, but in previous version this is not the case, so I'm getting conflicting functions regarding log2f. If I made the changes to always add -DHAVE_LOG2F (standard convention for autotools config.h) unconditionally, the library is uncompileable in older NDK version because log2f is undefined. But if I didn't add it, it fails to build in r19 because conflicting log2f (let alone r20). The problematic arch is armeabi-v7a as this problem simply non-existent in x86 and arm64-v8a (log2f always defined regardless).

I'd like to make sure my Android.mk support older NDK version to support more older devices but at this point it's no longer possible? How would I detect for such case and what action is the best I can take?

The text was updated successfully, but these errors were encountered:

alexcohn · 2019-07-01T06:26:06Z

To detect the current version of NDK, you can read the file source.properties at ${NDK_ROOT}. This is how the official Cmake toolchain file sniffs the version. You can also check the version of your clang (7.0.2 for NDK r18).

MikuAuahDark · 2019-07-01T07:24:47Z

Unfortunately the build system is using traditional ndk-build and not CMake. Is there a way to parse that source.properties which works both in Windows (non-MinGW env, let alone Cygwin) and Linux? Pada tanggal Sen, 1 Jul 2019 14.26, Alex Cohn <notifications@github.com> menulis:

…

To detect the current version of NDK, you can read the file *source.properties* at ${NDK_ROOT}. This is how the official Cmake toolchain file sniffs the version. You can also check the version of your *clang* (7.0.2 for NDK r18). — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1029>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABZHFFW7BY37JNMOSES3O3LP5GPQNANCNFSM4H4JQN3A> .

alexcohn · 2019-07-01T13:44:58Z

Sure you can parse source.properties file in your Android.mk:

include $(ANDROID_NDK_ROOT)/source.properties
$(info $(Pkg.Revision))

gives me 19.1.5304403

MikuAuahDark · 2019-07-01T14:41:52Z

Then how would I check if it's r19 or later?

I was thinking of writing little Python script which checks for user-supplied NDK version and return output yes or no based on NDK source.properties and execute the script at top-level Android.mk. Is this foolproof solution?

enh · 2019-07-01T14:47:31Z

i don't think you should be trying to detect the NDK version at all... why not try to fix the real problem?

here's what's in <math.h>:

float log2f(float __x) __INTRODUCED_IN(18);

and that hasn't changed since bionic SHA 50cda38 in 2017-09-14, so something doesn't make sense here.

so it seems like your configure file is wrong, and is just looking for the function in libc.so, not the header?

MikuAuahDark · 2019-07-01T14:53:44Z

They're somehow defined later when using R19 (after looking, I think it's R17) by android_support which somehow implicitly added.

enh · 2019-07-01T14:59:00Z

okay. but why's that a problem? if you have a working log2f (and the the android_support one is the latest OS version), that's fine, right?

MikuAuahDark · 2019-07-01T15:18:49Z

No. It result in conflicting function.

The Android.mk adds -DHAVE_LOG2F for ARM64 build so it's not a problem. But not for ARMv7 build because the app targets minimum-possible Android API-level (for r16, it's 14). In NDK r19, it's minimum to Android-16 so it targets Android-16 and as your code tell that log2f is defined for Android-18, but nope.

  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/Alc/ALc.c:33:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include\alSource.h:6:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include/alu.h:15:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include/alFilter.h:6:
  D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/common\math_defs.h:26:21: error: static declaration of 'log2f' follows non-static declaration
  static inline float log2f(float f)
                      ^
  D:/Application/android-ndk-r19c/build//../toolchains/llvm/prebuilt/windows-x86_64/sysroot/usr/local/include\math.h:38:15: note: previous declaration is here
  float         log2f(float);
                ^
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/Alc/ALu.c:30:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include\alSource.h:6:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include/alu.h:15:
  In file included from D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/OpenAL32/Include/alFilter.h:6:
  D:/Data/Development/love-dev/love-android/love/src/jni/openal-soft-1.18.2/common\math_defs.h:26:21: error: static declaration of 'log2f' follows non-static declaration
  static inline float log2f(float f)
                      ^
  D:/Application/android-ndk-r19c/build//../toolchains/llvm/prebuilt/windows-x86_64/sysroot/usr/local/include\math.h:38:15: note: previous declaration is here
  float         log2f(float);
                ^
  1 error generated.
  make: *** [D:/Data/Development/love-dev/love-android/love/build/intermediates/ndkBuild/release/obj/local/armeabi-v7a/objs/openal/Alc/ALu.o] Error 1
  make: *** Waiting for unfinished jobs....
  1 error generated.
  make: *** [D:/Data/Development/love-dev/love-android/love/build/intermediates/ndkBuild/release/obj/local/armeabi-v7a/objs/openal/Alc/ALc.o] Error 1

Checking that file math.h in NDK r19 shows these.

#if __ANDROID_API__ < __ANDROID_API_J_MR2__
double        log2(double);
float         log2f(float);
long double   log2l(long double);
long double   logbl(long double);
float         tgammaf(float);
#endif

Which tells it to define log2f regardless of Android API level.

enh · 2019-07-01T15:39:06Z

right, so the problem is in your "math_defs.h". luckily it looks like that's already been fixed upstream, so you just need to update to a newer version of openal:

kcat/openal-soft@27fbccf#diff-f9f627f11d5acea65cc397aaff3fbc73

MikuAuahDark · 2019-07-02T01:07:05Z

Sadly it doesn't make it into OpenAL-soft 1.19.1.

Back again, does this solution foolproof?

DanAlbert · 2019-07-02T01:52:01Z

If you can't fix openal-soft, the right way to do it would be to set that define conditionally based on __NDK_MAJOR__.

MikuAuahDark · 2019-07-02T02:02:00Z

I would just plug that into the config.h. Thank you very much.

DanAlbert · 2019-07-02T02:35:22Z

(depending on how old of an NDK you need to support, you may want to be aware that __NDK_MAJOR__ hasn't always been available, but it's safe to assume that if it isn't defined then you're using an old NDK and can fall back to the pre-r19 behavior)

MikuAuahDark · 2019-07-02T03:12:50Z

The project minimum supported NDK is r16. According to #407, it should be available in r16 (also can confirm it exist in r16b).

DanAlbert · 2019-07-02T03:13:47Z

Yeah, not something you have to worry about then.

MikuAuahDark added the question label Jun 29, 2019

enh closed this as completed Jul 1, 2019

0181532686cf4a31163be0bf3e6bb6732bf mentioned this issue Sep 16, 2021

atomic: detect clang separately libsdl-org/SDL#4755

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[question] Detect NDK r19 or later. #1029

[question] Detect NDK r19 or later. #1029

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[question] Detect NDK r19 or later. #1029

[question] Detect NDK r19 or later. #1029

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