Bug #20451: Bad Ruby 3.1.5 backport causes fiddle to fail to build

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: 3.1.5p252
• Backport: 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: DONTNEED, 3.3: DONTNEED

[Bo98 (Bo Anderson)]

Ruby 3.1.5 shipped with the following backport: https://github.com/ruby/ruby/commit/84f2aabd272a54e79979795d2d405090704a1d07

However this backport directly breaks the build:

closure.c:279:60: error: use of undeclared identifier 'data'
    result = ffi_prep_closure(pcl, cif, callback, (void *)(data->self));
                                                           ^

The original commit (https://github.com/ruby/fiddle/commit/2530496602) was updating the second branch to match the change in the first branch a couple lines up. However that change in the other branch does not exist in Ruby 3.1. The commit in question requires a previous commit of https://github.com/ruby/fiddle/commit/81a8a56239973ab7559229830a449d201955b494.

The backport should either be reverted or an other commit should also be backported. Note that these commits were in a series of many commits made to fix an upstream issue https://github.com/ruby/fiddle/issues/102 so I cannot vouch whether or not the two commits are sufficient to fix the originally reported issue.

[ylecuyer (Yoann Lecuyer)]

Additional information:

From fiddle extconf:

case
when $mswin, $mingw, (libffi_version && (libffi_version <=> [3, 2]) >= 0)
  $defs << "-DUSE_FFI_CLOSURE_ALLOC=1"
when (libffi_version && (libffi_version <=> [3, 2]) < 0)
else
  have_func('ffi_closure_alloc', ffi_header)
end

and closure.c

#if USE_FFI_CLOSURE_ALLOC
    result = ffi_prep_closure_loc(pcl, cif, callback,
		(void *)self, cl->code);
#else
    result = ffi_prep_closure(pcl, cif, callback, (void *)(data->self));
    cl->code = (void *)pcl;
    i = mprotect(pcl, sizeof(*pcl), PROT_READ | PROT_EXEC);
    if (i) {
	rb_sys_fail("mprotect");
    }
#endif

With libffi > 3.2 it compiles without any issue (I tried with 3.4.4) and with older version there is the error described (test with 3.1.0)

[ylecuyer (Yoann Lecuyer)]

I went ahead and created https://github.com/ruby/ruby/pull/10695 to revert the faulty backport

@unak who you mind review it and release the patch version if accepted?

I checked the repro https://github.com/ruby/fiddle/issues/102#issuecomment-1241763091 within fedora 36 and everything is ok.

If people are still having an issue as described in https://github.com/ruby/fiddle/issues/102 they can bump to ruby 3.2 or 3.3 where it should be fixed

[nobu (Nobuyoshi Nakada)]

• Backport changed from 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN to 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: DONTNEED, 3.3: DONTNEED

It seems a4ad6bd9aac564e93219284c912b26a72f9e82fc is missing.
https://github.com/ruby/ruby/pull/10696

[ylecuyer (Yoann Lecuyer)]

• File Dockerfile.ol8 Dockerfile.ol8 added

I tested both PR with ol8/ol9 using the attached dockerfile and they both work OK

I'll close my PR in favor of yours as it is more complete regarding the backport.