re2.v0.11.0 build fails on armv6l because gcc doesn't have the -m32 flag

[kevin1]

While compiling this package on my armv6 (32-bit) Raspberry Pi, gcc gave this error:

g++: error: unrecognized command line option ‘-m32’
Makefile:160: recipe for target 'obj/util/arena.o' failed

The -m32 and -m64 flags aren't available on ARM because (unlike on Intel), there are separate 32/64-bit gcc toolchains. (source)

I tracked down where the flag gets added in src/re2_c/jbuild:

if ! ${ARCH_SIXTYFOUR}; then
  CXX=\"$CXX -m32\"
fi

But I wasn't sure what the best way to exclude ARM without breaking the existing functionality. Thanks in advance for your help!

[dwang20151005]

@diml @trefis Maybe one of you can help with this? Also, we now prefer ocaml-re over re2. If you are able to switch, we recommend that instead. https://github.com/ocaml/ocaml-re

[kevin1]

Thanks dwang. To give some more context, opam was installing re2 as a dependency of patdiff.

I suppose we can change the script to say to check the output of uname and not add this flag if we are on ARM.

[MattWindsor91]

This is also happening on arm-linux-gnueabihf (Raspberry Pi 3B+, Raspbian buster (32-bit, apparently - TIL), OCaml 4.09, opam 2.0.6, dune 2.1.3) and blocking an install of shell v0.13.0. (EDIT: not core-kernel, oops)

The lines mentioned above are now https://github.com/janestreet/re2/blob/master/src/re2_c/dune#L18-L20 - I've worked around the issue by getting the v0.13.0 tarball and deleting those lines.

If some can provide a patch to fix armv6l compilation, we'll integrate it.

[mooreryan]

Also, we now prefer ocaml-re over re2. If you are able to switch, we recommend that instead. https://github.com/ocaml/ocaml-re

Does this mean that re2 is no longer used/recommended even by Jane Street?

Edit: Just saw this article: https://blog.janestreet.com/what-the-interns-have-wrought-2020/. I guess it isn't being used anymore.