Build fails on arm: undefined reference to `__aeabi_unwind_cpp_pr*'

[doughdemon]

gcc -Wl,-EL -shared -Wl,--warn-common -Wl,--warn-once -Wl,-z,combreloc -Wl,-z,relro -Wl,-z,now -Wl,--hash-style=gnu -Wl,-O2 -Wl,-z,defs -Wl,-s -Wl,-soname=libubacktrace.so.0 -nostdlib -nostartfiles -o libubacktrace.so.0.0 backtracesyms.o backtracesymsfd.o backtrace.o -lc -ldl
backtracesyms.o:(.ARM.exidx+0x0): undefined reference to `__aeabi_unwind_cpp_pr0'
backtracesymsfd.o:(.ARM.exidx+0x0): undefined reference to `__aeabi_unwind_cpp_pr1'
collect2: error: ld returned 1 exit status
Makefile:46: recipe for target 'libubacktrace.so.0.0' failed
make: *** [libubacktrace.so.0.0] Error 1

with

gcc version 4.9.3 (Gentoo Hardened 4.9.3-r99 p1.2, pie-0.6.3)

Adding "-lgcc_eh" makes it compile.

[blueness]

should that only be added for arm or is it save for other arches?

[doughdemon]

should that only be added for arm or is it save for other arches?

I think that it is safe for all arches but not the correct thing to do. I should have also said that I'm using musl. Anyway, the library does not work at all on arm because there is no symbol _Unwind_GetGR in libgcc_s.so. <unwind.h> has ``` #define _Unwind_GetIP(context) \ (_Unwind_GetGR (context, 15) & ~(_Unwind_Word)1) ```