ndk-build always links libstdc++ #105

DanAlbert · 2016-05-24T23:24:03Z

$ readelf -d sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_shared.so
...
0x00000001 (NEEDED)                     Shared library: [libstdc++.so]
...

This is actually because ndk-build always links libstdc++ since we don't use -nodefaultlibs. We should fix this.

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

An alternative implementation would be to use `-nodefaultlibs`, but that seems a bit more fragile. In the platform we use `-nodefaultlibs`, but it took us quite a while to get that right. Bug: android/ndk#105 Change-Id: I417f4afbfd46288d2eeffc85f056a6dc8a3a117d

First, enable fatal linker warnings since responsible users will do that too. Second, build an executable rather than a shared libray. The linker only checks certain warnings (such as unavailable shared libraries in the DT_NEEDED of your dependencies) when building executables. With these two changes, we would have noticed android/ndk#105 affecting libc++_shared at test time rather than via manual inspection. Change-Id: I0cb06755318064325d235d1d8de6be442fd60ae7

DanAlbert · 2017-08-22T23:32:58Z

Went to add -nostdlib++ to Clang and found that @nico beat me to it: https://reviews.llvm.org/D35780 (thanks!)

@srhines @pirama-arumuga-nainar: Not sure if you've picked a revision for the next update yet. Could you make sure that patch is included?

AstralStorm · 2017-09-06T08:14:17Z

Also affects cmake builds in 16.0.4293906 rc1 and older.

Hacky workaround if you want to patch it in android.toolchain.cmake (replace to ANDROID_*_FLAGS in that case) follows. This workaround doesn't seem to break anything, but might be adding a few too many libs in fact.

Workaround:
if(NOT CMAKE_CXX_FLAGS MATCHES "nostdlib" AND NOT CMAKE_CXX_FLAGS MATCHES "nodefaultlibs")
set(CMAKE_POLICY_DEFAULT_CMP0056 NEW)
string(CONCAT CMAKE_CXX_FLAGS "-nodefaultlibs " "${CMAKE_CXX_FLAGS}")
string(CONCAT CMAKE_SHARED_LINKER_FLAGS "-lc -lm -ldl " "${CMAKE_SHARED_LINKER_FLAGS}")
string(CONCAT CMAKE_EXE_LINKER_FLAGS "-lc -lm -ldl " "${CMAKE_EXE_LINKER_FLAGS}")
endif()

Equivalent could be applied in ndk-build scripts.

java4ada · 2017-10-16T06:57:06Z

ETA ?

DanAlbert · 2017-10-16T07:12:35Z

Whenever we get a clang update. Probably r17.

DanAlbert · 2017-12-06T23:07:46Z

https://android-review.googlesource.com/#/c/platform/ndk/+/558900

wang-bin · 2017-12-07T02:07:52Z

Why a new option -nostdlib++? libstdc++ is the default for clang, but explicitly setting -stdlib=libc++ is enough. I use the option since r13 without any problem.

DanAlbert · 2017-12-07T04:15:19Z

That is not equivalent. libc++.so and libc++.a in the NDK are linker scripts that link all their dependencies. These exist to facilitate standalone toolchains. It is not possible for the link order to be exactly correct using this method, and you run the risk of hitting #379.

wang-bin · 2017-12-07T06:11:59Z

That is not equivalent

Yes. -nostdlib++ disables both libc++ and libstdc++

libc++.so and libc++.a in the NDK are linker scripts that link all their dependencies

I knew it. In fact I wondered why not removing the full path of libc++.so in linker flags. -stdlib=libc++ will replace -lstdc++ by -lc++, and because of libc++.so is a script, libc++_shared.so and some other libraries are linked. I got exactly the same binary without the full path libc++.so. But I can't remove it without modifying android.toolchain.cmake.

These exist to facilitate standalone toolchains

I use cmake

It is not possible for the link order to be exactly correct using this method, and you run the risk of hitting #379

Not sure. No problem found yet

thughes · 2018-04-03T19:12:10Z

@DanAlbert Why does nostdlib++ not apply when using STLport?
https://android.googlesource.com/platform/ndk.git/+/master/build/cmake/android.toolchain.cmake#332

I don't know much about STLport (and am not using it for my ndk build), but it's not entirely clear to me why it should be special:
https://developer.android.com/ndk/guides/cpp-support.html#stlport
https://developer.android.com/ndk/guides/cpp-support.html#one_stl_per_app

I'm trying to make sure cmake (without using the toolchain file) has the right behavior:
https://gitlab.kitware.com/cmake/cmake/merge_requests/1919
https://gitlab.kitware.com/cmake/cmake/issues/17863

The chosen STL libraries are already linked explicitly so we shouldn't let the compiler add its implicit `-lstdc++` (the default) when invoking the linker. Fixes: #17863 NDK-Issue: android/ndk#105 Inspired-by: Tom Hughes <tomtheengineer@gmail.com>

This prevents Clang from automatically linking libstdc++ when we don't want it to. It needs to for the system STL and for stlport (which gets new/delete from the system STL), but for gnustl and libc++ we don't want this linked. Test: ./checkbuild.py && ./run_tests.py Bug: android/ndk#105 Change-Id: I2c5d6d6212f6b9f3552934100f2ed970fd8340ab

DanAlbert · 2018-05-03T17:36:11Z

Sorry, missed this update.

Bionic's libstdc++ is really more akin to libc++about or libsupc++ (though not complete). It contains an implementation of new and delete, and not much else. Stlport does not include these, so it gets new/delete from bionic's libstdc++.

Not that this is very relevant now. There's not much reason to use stlport starting with r16 and it doesn't exist at all in master.

cybertk · 2018-06-05T14:29:55Z

The issue still exists in NDK r17 while building with ndk-build, is there any fix plan or workaround?

cybertk · 2018-06-05T15:13:25Z

NDK r16b works fine with same project configuration

APP_PLATFORM := android-16
APP_ABI := arm64-v8a
APP_STL := c++_shared
APP_CPPFLAGS += -std=c++11 -fexceptions

DanAlbert · 2018-06-05T20:22:32Z

No it doesn't?

// foo/jni/foo.cpp
int main(int argc, char** argv) {
  return 0;
}

# foo/jni/Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := foo
LOCAL_SRC_FILES := foo.cpp
include $(BUILD_EXECUTABLE)

# foo/jni/Application.mk
APP_STL := c++_shared
APP_CPPFLAGS := -std=c++11 -fexceptions

$ android-ndk-r17/ndk-build -C foo APP_ABI=arm64-v8a V=1 APP_LDFLAGS=-v -B
Android NDK: APP_PLATFORM not set. Defaulting to minimum supported version android-14.
make: Entering directory `/work/src/ndk/ndk/foo'
rm -f ./libs/arm64-v8a/* ./libs/armeabi-v7a/* ./libs/x86/* ./libs/x86_64/*
rm -f ./libs/arm64-v8a/gdbserver ./libs/armeabi-v7a/gdbserver ./libs/x86/gdbserver ./libs/x86_64/gdbserver
rm -f ./libs/arm64-v8a/gdb.setup ./libs/armeabi-v7a/gdb.setup ./libs/x86/gdb.setup ./libs/x86_64/gdb.setup
[arm64-v8a] Compile++      : foo <= foo.cpp
/work/src/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -MMD -MP -MF ./obj/local/arm64-v8a/objs/foo/foo.o.d -gcc-toolchain /work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64 -target aarch64-none-linux-android -ffunction-sections -funwind-tables -fstack-protector-strong -fpic -Wno-invalid-command-line-argument -Wno-unused-command-line-argument -no-canonical-prefixes
 -g -fno-exceptions -fno-rtti -O2 -DNDEBUG  -I/work/src/android-ndk-r17/sources/cxx-stl/llvm-libc++/include -I/work/src/android-ndk-r17/sources/cxx-stl/llvm-libc++/../llvm-libc++abi/include -Ijni -std=c++11  -std=c++11 -fexceptions  -DANDROID  -D__ANDROID_API__=21 -Wa,--noexecstack -Wformat -Werror=format-security -fpie   --sysroot /work/src/android-ndk-r17/sysroot -isystem /work/src/android-ndk-r17/sysroot/usr/include/aarch64-linux-android -c  jni/foo.cpp -o ./obj/local/arm64-v8a/objs/foo/foo.o
[arm64-v8a] Prebuilt       : libc++_shared.so <= <NDK>/sources/cxx-stl/llvm-libc++/libs/arm64-v8a/
cp -f /work/src/android-ndk-r17/sources/cxx-stl/llvm-libc++/libs/arm64-v8a/libc++_shared.so obj/local/arm64-v8a/libc++_shared.so
[arm64-v8a] Executable     : foo
/work/src/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -Wl,--gc-sections -Wl,-z,nocopyreloc --sysroot=/work/src/android-ndk-r17/platforms/android-21/arch-arm64 -Wl,-rpath-link=/work/src/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib -Wl,-rpath-link=./obj/local/arm64-v8a ./obj/local/arm64-v8a/objs/foo/foo.o -lgcc -Wl,--exclude-libs,libgcc.a -latomic -Wl,--exclude-libs,libatomic.a ./obj/local/arm64-v8a/libc++_shared.so  -gcc-toolchain /work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64 -target aarch64-none-linux-android -no-canonical-prefixes   -Wl,--build-id -nostdlib++ -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--warn-shared-textrel -Wl,--fatal-warnings -fpie -pie -v  -lc -lm -o ./obj/local/arm64-v8a/foo
Android (4691093 based on r316199) clang version 6.0.2 (https://android.googlesource.com/toolchain/clang 183abd29fc496f55536e7d904e0abae47888fc7f) (https://android.googlesource.com/toolchain/llvm 34361f192e41ed6e4e8f9aca80a4ea7e9856f327) (based on LLVM 6.0.2svn)
Target: aarch64-none-linux-android
Thread model: posix
InstalledDir: /work/src/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin
Found candidate GCC installation: /work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x
Selected GCC installation: /work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld" --sysroot=/work/src/android-ndk-r17/platforms/android-21/arch-arm64 -pie --fix-cortex-a53-843419 --eh-frame-hdr -m aarch64linux -dynamic-linker /system/bin/linker64 -o ./obj/local/arm64-v8a/foo /work/src/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib/crtbegin_dynamic.o -L/work/src/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/6.0.2/lib/linux/aarch64 -L/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x -L/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/lib/../lib64 -L/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/lib -L/work/src/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib --gc-sections -z nocopyreloc -rpath-link=/work/src/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib -rpath-link=./obj/local/arm64-v8a ./obj/local/arm64-v8a/objs/foo/foo.o -lgcc --exclude-libs libgcc.a -latomic --exclude-libs libatomic.a ./obj/local/arm64-v8a/libc++_shared.so --build-id --no-undefined -z noexecstack -z relro -z now --warn-shared-textrel --fatal-warnings -lc -lm -lm -lgcc -lgcc -ldl -lc -lgcc -lgcc -ldl /work/src/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib/crtend_android.o
[arm64-v8a] Install        : foo => libs/arm64-v8a/foo
install -p ./obj/local/arm64-v8a/foo ./libs/arm64-v8a/foo
/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/bin/aarch64-linux-android-strip --strip-unneeded  ./libs/arm64-v8a/foo
[arm64-v8a] Install        : libc++_shared.so => libs/arm64-v8a/libc++_shared.so
install -p ./obj/local/arm64-v8a/libc++_shared.so ./libs/arm64-v8a/libc++_shared.so
/work/src/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/bin/aarch64-linux-android-strip --strip-unneeded  ./libs/arm64-v8a/libc++_shared.so
make: Leaving directory `/work/src/ndk/ndk/foo'
$ readelf -dW foo/libs/arm64-v8a/foo | grep stdc
$

cybertk · 2018-06-06T09:13:04Z

Here is my error with r17,

[arm64-v8a] Executable     : foo
/root/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -Wl,--gc-sections -Wl,-z,nocopyreloc --sysroot=/root/android-ndk-r17/platforms/android-21/arch-arm64 -Wl,-rpath-link=/root/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib -Wl,-rpath-link=./obj/local/arm64-v8a ./obj/local/arm64-v8a/objs/foo/main.o -lgcc -Wl,--exclude-libs,libgcc.a -latomic -Wl,--exclude-libs,libatomic.a ./obj/local/arm64-v8a/libA.so ./obj/local/arm64-v8a/libB.so ./obj/local/arm64-v8a/libC.so ./obj/local/arm64-v8a/libc++_shared.so  -gcc-toolchain /root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64 -target aarch64-none-linux-android -no-canonical-prefixes   -Wl,--build-id -nostdlib++ -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--warn-shared-textrel -Wl,--fatal-warnings -fpie -pie   -lc -lm -o ./obj/local/arm64-v8a/foo
/root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld: ./obj/local/arm64-v8a/foo: hidden symbol `_Unwind_Resume' in /root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/libgcc.a(unwind-dw2.o) is referenced by DSO
/root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld: final link failed: Bad value
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [obj/local/arm64-v8a/foo] Error 1

DanAlbert · 2018-07-09T22:47:17Z

That doesn't seem to have anything to do with this bug. You'll need to file a new bug with a test case.

pengzhendong · 2021-06-03T10:23:51Z

Here is my error with r17,

[arm64-v8a] Executable     : foo
/root/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -Wl,--gc-sections -Wl,-z,nocopyreloc --sysroot=/root/android-ndk-r17/platforms/android-21/arch-arm64 -Wl,-rpath-link=/root/android-ndk-r17/platforms/android-21/arch-arm64/usr/lib -Wl,-rpath-link=./obj/local/arm64-v8a ./obj/local/arm64-v8a/objs/foo/main.o -lgcc -Wl,--exclude-libs,libgcc.a -latomic -Wl,--exclude-libs,libatomic.a ./obj/local/arm64-v8a/libA.so ./obj/local/arm64-v8a/libB.so ./obj/local/arm64-v8a/libC.so ./obj/local/arm64-v8a/libc++_shared.so  -gcc-toolchain /root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64 -target aarch64-none-linux-android -no-canonical-prefixes   -Wl,--build-id -nostdlib++ -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--warn-shared-textrel -Wl,--fatal-warnings -fpie -pie   -lc -lm -o ./obj/local/arm64-v8a/foo
/root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld: ./obj/local/arm64-v8a/foo: hidden symbol `_Unwind_Resume' in /root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/libgcc.a(unwind-dw2.o) is referenced by DSO
/root/android-ndk-r17/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld: final link failed: Bad value
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [obj/local/arm64-v8a/foo] Error 1

Same error, have you fixed that?

enh-google · 2021-06-03T16:19:21Z

r17 is no longer supported. please try again with a current NDK, and file a new bug if you still have trouble with that.

DanAlbert · 2021-06-03T18:29:44Z

Please file new bugs if you have new bugs. As I responded to the original commenter for that error, it has nothing to do with the topic of this thread. We want to help, but we can't fix r17 and we can't fix bugs we can't see, so we need a bug filed with a repro case to do so.

DanAlbert added this to the r13 milestone May 24, 2016

DanAlbert self-assigned this May 24, 2016

DanAlbert modified the milestones: r14, r13 Aug 9, 2016

DanAlbert added fixit-candidate help wanted and removed fixit-candidate labels Nov 12, 2016

DanAlbert removed this from the r14 milestone Jan 4, 2017

DanAlbert added clang and removed help wanted labels Aug 22, 2017

AstralStorm mentioned this issue Sep 14, 2017

Missing libgcc in libc++.a breaks clang c++_static build #515

Closed

DanAlbert added this to the r17 milestone Oct 2, 2017

DanAlbert closed this as completed Dec 7, 2017

dec1 mentioned this issue Jul 23, 2018

What STL were the prebuilt libraries built with? dec1/Boost-for-Android#9

Closed

caikelun mentioned this issue Nov 6, 2019

[improve] don't link against libstdc++ on libxcrash_dumper iqiyi/xCrash#22

Closed

android locked as resolved and limited conversation to collaborators Jun 3, 2021

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ndk-build always links libstdc++ #105

ndk-build always links libstdc++ #105

DanAlbert commented May 24, 2016

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ndk-build always links libstdc++ #105

ndk-build always links libstdc++ #105

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