undefined reference to 'frexpl'

[Klayflash]

Description

I've switched from android-ndk-r15-windows-x86_64 to android-ndk-r16-beta1-windows-x86_64.
Linker error:
C:\lib\android\2\android-ndk-r16-beta1-windows-x86_64\android-ndk-r16-beta1\build\tools\stoolchain_x86\bin..\lib\gcc\i686-linux-android\4.9.x........\include\c++\4.9.x/math.h:902: error: undefined reference to 'frexpl'

Environment Details

Standalone toolchain was created by cmd file:

@echo off
set API_LEVEL=19
set STL=libc++
set COMMON_PARAMS=-v
set NDK_ROOT=%~dp0\..\..
set PYTHON=%NDK_ROOT%\prebuilt\windows-x86_64\bin\python.exe

"%PYTHON%" make_standalone_toolchain.py --arch x86 --api %API_LEVEL% --stl %STL% --install-dir stoolchain_x86 %COMMON_PARAMS%
if ERRORLEVEL 1 goto error

"%PYTHON%" make_standalone_toolchain.py --arch arm --api %API_LEVEL% --stl %STL% --install-dir stoolchain_arm %COMMON_PARAMS%
if ERRORLEVEL 1 goto error

:success
echo SUCCESS!!!
goto exit
:error
echo ERROR!!!
goto exit
:exit
pause

Linker flags:
-shared -Wl,-soname,symbols.so -Wl,--version-script=libcode.version -Wl,--no-undefined -Wl,--fatal-warnings -Wl,--gc-sections -Wl,--icf=safe -llog -lm -landroid -landroid_support -lEGL -lGLESv3 -fPIC -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security -O0 -fno-limit-debug-info -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now OBJECTS_FILES_HERE C:\\lib\\android\\2\\android-ndk-r16-beta1-windows-x86_64\\android-ndk-r16-beta1\\build\\tools\\stoolchain_x86\\i686-linux-android\\lib\\libstdc++.a -o libmy.so

• 16.0.4293906-beta1
• standalone toolchain + custom build system
• Host OS: Windows
• Compiler: Clang
• ABI: x86
• STL:
• NDK API level: 19

[Klayflash]

By using
nm --demangle --defined-only --line-numbers %FROM% > TO.txt
I've found that file
android-ndk-r15-windows-x86_64\android-ndk-r15\build\tools\stoolchain_x86\i686-linux-android\lib\libandroid_support.a
contains frexpl and file
android-ndk-r16-beta1-windows-x86_64\android-ndk-r16-beta1\build\tools\stoolchain_x86\i686-linux-android\lib\libandroid_support.a
does not contain frexpl

[enh]

yeah, looks like 8127c9619e2a497a58e6db62df9916e4c4864608 regressed this.

new in r16's libandroid_support.a:

+acos
+acosh
+asin
+asinh
+atan
+atan2
+atanh
+c32rtomb
+cbrt
+copysignl
+cos
+cosh
+erf
+erfc
+exp
+exp2
+expm1
+fmaxl
+fminl
+hypot
+ilogbl
+__ldexp_cexp
+__ldexp_exp
+ldexpl
+lgamma
+llroundl
+log
+log10
+log1p
+logb
+logf
+lroundl
+mbrtoc32
+nearbyint
+nearbyintf
+nextafter
+nextafterl
+posix_memalign
+remainder
+remquo
+rint
+roundl
+scalbn
+setlocale
+sin
+sinh
+sqrt
+tan
+tanh

removed in r16's libandroid_support.a:

-frexp
-frexpf
-frexpl
-imaxabs
-imaxdiv
-iswalnum
-iswalpha
-iswcntrl
-iswctype
-iswdigit
-iswgraph
-iswlower
-iswprint
-iswpunct
-iswspace
-iswupper
-iswxdigit
-log2f
-lrintl
-mblen
-mbrlen
-mbstowcs
-nan
-nanf
-nanl
-printf
-snprintf
-snprintf_l
-sprintf
-sprintf_l
-sscanf_l
-strtod
-strtold_l
-strtol_l
-strtoll_l
-strtoul_l
-strtoull_l
-towctrans
-towlower
-towupper
-vasprintf_l
-vfprintf
-vfwprintf
-vprintf
-vsnprintf
-vsnprintf_l
-vsprintf
-vsprintf_l
-vsscanf_l
-vwprintf
-wcpcpy
-wcpncpy
-wcscasecmp
-wcslcat
-wcslcpy
-wcsncasecmp
-wcsncat
-wcsnlen
-wcstombs
-wcswidth
-wctob
-wctomb
-wctrans
-wctype
-wcwidth
-wprintf

ignoring the wchar_t and locale_t nonsense, and the removal of the alternative printf which is probably the most useful feature of the new libandroid_support, that's:

-frexp
-frexpf
-frexpl
-imaxabs
-imaxdiv
-log2f

these all seem to just have been an oversight. b04b1a2e39477518e963daaec34fffcb69852c04 claimed we don't need imaxabs/imaxdiv, but we still declare them in the support headers, so i'm not sure that's true.

-lrintl

this is missing from x86 because we have assembler implementations for x86 that come from a different source file than the arm stuff. not sure whether it makes more sense to just -DNDK_SUPPORT_LIBRARY and add an extra #if to the bionic source for this?

-nan
-nanf
-nanl

these were probably dropped on purpose because they're all before 14, which is the current minimum supported API level.

[enh]

suggested fix: https://android-review.googlesource.com/479202

[chri7325]

👍 I'm also seeing linker errors on r16 beta from math when targeting platform 16

android-16_arm/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../include/c++/4.9.x/math.h:1302: error: undefined reference to 'log2f'

[enh]

yeah, log2f was accidentally dropped from libandroid_support.a, which had previously been papering over that crack (log2f wasn't in API 16): https://android-review.googlesource.com/#/c/platform/ndk/+/479202/

[edkimmel]

Dan, I'm still seeing this problem with the ndk 16 beta. Are there steps I should take on my end, or just wait for a future r16 version?

sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/include/math.h
Error:(1302) undefined reference to 'log2f'

[enh]

you could try a nightly build until r16beta2: https://android.googlesource.com/platform/ndk/+/master/docs/ContinuousBuilds.md