Bug#977235: sentencepiece FTBFS on armel/mipsel: undefined reference to `__atomic_fetch_add_8'

[Adrian Bunk]

Source: sentencepiece
Version: 0.1.94-1
Severity: serious
Tags: ftbfs patch

https://buildd.debian.org/status/package.php?p=sentencepiece

...
/usr/bin/c++ -O3 -Wall -fPIC -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -Wl,-z,relro -Wl,-z,now -rdynamic CMakeFiles/spm_export_vocab.dir/spm_export_vocab_main.cc.o -o spm_export_vocab  -Wl,-rpath,/<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/src: libsentencepiece.so.0.0.0 -lpthread
/usr/bin/ld: libsentencepiece.so.0.0.0: undefined reference to `__atomic_fetch_add_8'
collect2: error: ld returned 1 exit status
make[4]: *** [src/CMakeFiles/spm_export_vocab.dir/build.make:107: src/spm_export_vocab] Error 1


Fix/Workaround:

--- debian/rules.old	2020-12-12 21:58:13.187467694 +0000
+++ debian/rules	2020-12-12 21:59:46.848833951 +0000
@@ -12,6 +12,9 @@
 DPKG_EXPORT_BUILDFLAGS = 1
 include /usr/share/dpkg/buildflags.mk
 
+ifneq (,$(filter $(DEB_HOST_ARCH), armel mipsel m68k powerpc sh4))
+  export DEB_LDFLAGS_MAINT_APPEND += -Wl,--no-as-needed -latomic -Wl,--as-needed
+endif
 
 %:
 	dh $@ --with python3 --buildsystem=cmake