Make fails with "incompatible function pointer type" on Apple m3

[jaydorsey]

What version of gRPC and what language are you using?

All grpc gem versions from 1.54.2 thru 1.59.2, ruby

What operating system (Linux, Windows,...) and version?

OS: macOS 14.1.1
Chip: M3 Max

What runtime / compiler are you using (e.g. python version or version of gcc)

ruby: 3.1.2 (and 3.2.2)
gcc: 13.2.0 (homebrew)
llvm: 17.0.6 (homebrew)
Command Line Tools: 15.0.0.0.1.1694021235
Xcode: 15.0.1

What did you do?

I'm trying to install the grpc gem on a new Macbook Pro with an M3 Max chip using the command gem install grpc -v 1.54.2

I've also tried cloning the repo & building from source/running tests

What did you expect to see?

I expected the gem to install after it builds from source

What did you see instead?

I see 1 error that causes the grpc build to fail:

rb_channel.c:764:40: error: incompatible function pointer types passing 'VALUE (VALUE)' (aka 'unsigned long (unsigned long)') to parameter of type 'VALUE (*)(void *)' (aka 'unsigned long (*)(void *)') [-Wincompatible-function-pointer-types]
  764 |   background_thread = rb_thread_create(run_poll_channels_loop, NULL);
      |                                        ^~~~~~~~~~~~~~~~~~~~~~

Anything else we should know about your project / environment?

I've tried installing with both default macOS binaries (gcc/clang, etc.) with similar results but a different set of error messages (ranlib, etc.)

I tried setting the relevant paths (LDFLAGS, CPPFLAGS, etc.) per the homebrew instructions, and without the paths.

I tried installing with ruby 3.2.2 with the same error

I tried installing 1.60.0.pre and that install worked so there may be a patch/workaround for it that I can upgrade to. I can't use this as a workaround in the current situation, because of cascading dependencies.

I'd love to find out that I'm missing something in the install, or that I've configured something wrong. The only solution that comes to mind is a) buying a new laptop (without an M3 chip); b) Forgetting about locally installing any of this and work inside of a docker container

I'm wondering if this is an issue related to the m3 chipset

[alto-ruby]

#35194 should be able to fix it.

The reason 1.60.0.pre installation succeeds is because started to distribute arm64 binary for mac, so no compiling is needed. It would be great if you can upgrade to 1.60.0 release to unblock yourself. @jaydorsey

@apolcyn Is it possible that we publish v1.54.2 arm64-darwin binary or back port the fix for this user?

[jaydorsey]

I can't upgrade in the project at this point, this only affects me and I can work around it by working inside of a docker container.

I was hoping that I was just missing some kind of build/library configuration. I think there's a homebrew install for 1.5.x but I can't seem to recreate whatever steps they do to build it.

If it's a potentially breaking change to backport it, it's probably not worth it. I know we'll update our library at some point and I do have a workaround. Thank you for looking at this though.

Happy to leave this issue open for others to chime in but we can also close it

[jaydorsey]

@alto-ruby I pulled down your patch, setup submodules, did a rake build, and then a gem install on the package.

I got a new error. I don't know much about C but I'll see if I can dig thru the diff between 1.54.2 and your change + 1.60 which does seem to compile just fine.

I'm also going to unpin grpc from our gemfile for local development, and then just discard those changes. Between those solutions, and docker, I have options to unblock me.

I appreciate you taking the time to look at this, thank you.

rb_channel.c:786:30: error: incompatible function pointer types passing 'void (void *)' to parameter of type 'void *(*)(void *)' [-Wincompatible-function-pointer-types]
  786 |   rb_thread_call_without_gvl(run_poll_channels_loop_unblocking_func, NULL, NULL,
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[alto-ruby]

It can be fixed the same way, I'll update the PR.
Sorry that I don't have the same environment to reproduce it, only fixing the errors you provided.

[alto-ruby]

I just found out that there is already #34481 fixing the same issue

[jaydorsey]

I just found out that there is already #34481 fixing the same issue

Oh thank you, I'll take a look. I think I tried installing w/ downgraded versions of many things (llvm, gcc, etc.) but I know I didn't look at clang.

I'll look at that related PR, I appreciate you following up on this!

I'm going to close this issue since it looks like the root cause/resolution is being addressed in that pull request, and that answered the heart of my original question "Am I missing some compilation flags that would let me get this working"

[jaydorsey]

@alto-ruby One quick update: based on your comment, I was able to fix my system and get grpc 1.54.2 installed!

1. brew install llvm@15
2. Add all the path/export changes it notes in the install output
3. Make sure you clear out any previous path/export overrides where llvm was configured (which is probably 17 if your install was recent)

After that, a regular old gem install grpc -v 1.54.2 or bundle install works. Thank you!

[technicalpickles]

I got curious if there's a less invasive way to work around the issue than installing llvm@15. Based on

#34481 talks about:

clang 16 defaults -Wincompatible-function-pointer-types to be on. This causes a number of hard errors due to implicit conversions between void * and void, such as:

If that is the case, it should be possible to turn it off right? Reading https://clang.llvm.org/docs/UsersManual.html#options-to-control-error-and-warning-messages make it seem like this could do it:

-Wno-error=incompatible-function-pointer-type

I'm used to being able to pass in things like that to CFLAGS, but either I'm not able to pass it in that way, or setting it on the command line doesn't make it all the way down to the generated Makefile 🤔

[flipsasser]

@technicalpickles you can use pass-thru arguments on gem install, so something like gem install grpc:[VERSION] -- -Wno-error=incompatible-function-pointer-type will pass those flags on to the compiler

I mean, that didn't actually WORK for me, but I'm experimenting with flags now. Sigh. This is a pain!

[oleg-vinted]

If you're using Bundler, you can set this override like this:

bundle config set --global build.grpc "--with-cflags=-Wno-error=incompatible-function-pointer-types"

Ref https://bundler.io/v2.5/man/bundle-config.1.html#BUILD-OPTIONS

[stathis-alexander]

FYI - Looks like this issue is fixed in 1.62.1

[pprencel]

@technicalpickles @flipsasser
One of those solutions should work for you:
gem install grpc -v 1.54.2 -- --with-cflags=-Wno-error=incompatible-function-pointer-types
or
bundle config set --global build.grpc "--with-cflags=-Wno-error=incompatible-function-pointer-types"

Actually grpc build error relates to Wincompatible-function-pointer-types, not Wincompatible-function-pointer-type
So it looks like it won't work for you because of the typo 🤭