Error installing v0.18.1 on Ruby v3.4.8 on MacOSX x86

Start with the native extension build output for mini_racer 0.18.1 and compare the failing mini_racer_v8.cc compilation on Ruby 3.4.8 with the reported working Ruby 3.4.7 setup. The issue gives no compiler error details beyond make failing, so first collect the full compiler output and check the existing Ruby 3.4 compatibility discussion, including issue #359. Done when installation succeeds on the reported macOS and Ruby version.

I have updated to Ruby v3.4.8 and the v0.18.1 doesn't work anymore (it worked with Ruby v3.4.7).
It means that while building with native extensions, I get an error and I can't continue.

$ bundle
Fetching gem metadata from https://rubygems.org/........
Resolving dependencies...
Installing mini_racer 0.18.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/mini_racer-0.18.1/ext/mini_racer_extension
/Users/antonio.facciolo/.rbenv/versions/3.4.8/bin/ruby extconf.rb
checking for -lpthread... yes
checking for -lobjc... yes
checking for whether -Wl,--exclude-libs=ALL  is accepted as LDFLAGS... no
creating Makefile

current directory: /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/mini_racer-0.18.1/ext/mini_racer_extension
make DESTDIR\= sitearchdir\=./.gem.20260105-54121-b5e9b7 sitelibdir\=./.gem.20260105-54121-b5e9b7 clean

current directory: /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/mini_racer-0.18.1/ext/mini_racer_extension
make DESTDIR\= sitearchdir\=./.gem.20260105-54121-b5e9b7 sitelibdir\=./.gem.20260105-54121-b5e9b7
compiling mini_racer_extension.c
In file included from mini_racer_extension.c:13:
./serde.c:101:27: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  101 |     n = next_power_of_two(n);
      |         ~~~~~~~~~~~~~~~~~ ^
./serde.c:111:14: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  111 |     b->cap = n;
      |            ~ ^
./serde.c:393:29: warning: implicit conversion loses integer precision: 'uint64_t' (aka 'unsigned long long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  393 |         des_object_ref(arg, u);
      |         ~~~~~~~~~~~~~~      ^
./serde.c:567:33: warning: implicit conversion loses integer precision: 'uint64_t' (aka 'unsigned long long') to 'int' [-Wshorten-64-to-32]
  567 |         des_bigint(arg, *p, u, 1-2*t);
      |         ~~~~~~~~~~             ~^~~~
mini_racer_extension.c:599:23: warning: incompatible pointer types passing 'unsigned long[64]' to parameter of type 'const uint64_t *' (aka 'const unsigned long long *')
[-Wincompatible-pointer-types]
  599 |         ser_bigint(s, limbs, countof(limbs), sign);
      |                       ^~~~~
./serde.c:269:48: note: passing argument to parameter 'p' here
  269 | static void ser_bigint(Ser *s, const uint64_t *p, size_t n, int sign)
      |                                                ^
mini_racer_extension.c:524:32: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  524 |             ser_array_begin(s, n);
      |             ~~~~~~~~~~~~~~~    ^
mini_racer_extension.c:528:30: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  528 |             ser_array_end(s, n);
      |             ~~~~~~~~~~~~~    ^
mini_racer_extension.c:530:31: warning: implicit conversion loses integer precision: 'long' to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  530 |             ser_object_ref(s, FIX2LONG(id));
      |             ~~~~~~~~~~~~~~    ^~~~~~~~~~~~
/Users/antonio.facciolo/.rbenv/versions/3.4.8/include/ruby-3.4.0/ruby/internal/arithmetic/long.h:46:22: note: expanded from macro 'FIX2LONG'
   46 | #define FIX2LONG     RB_FIX2LONG          /**< @old{RB_FIX2LONG} */
      |                      ^
/Users/antonio.facciolo/.rbenv/versions/3.4.8/include/ruby-3.4.0/ruby/internal/arithmetic/long.h:53:22: note: expanded from macro 'RB_FIX2LONG'
   53 | #define RB_FIX2LONG  rb_fix2long          /**< @alias{rb_fix2long} */
      |                      ^
mini_racer_extension.c:559:35: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  559 |                 ser_object_end(s, n);
      |                 ~~~~~~~~~~~~~~    ^
mini_racer_extension.c:564:31: warning: implicit conversion loses integer precision: 'long' to 'uint32_t' (aka 'unsigned int') [-Wshorten-64-to-32]
  564 |             ser_object_ref(s, FIX2LONG(id));
      |             ~~~~~~~~~~~~~~    ^~~~~~~~~~~~
/Users/antonio.facciolo/.rbenv/versions/3.4.8/include/ruby-3.4.0/ruby/internal/arithmetic/long.h:46:22: note: expanded from macro 'FIX2LONG'
   46 | #define FIX2LONG     RB_FIX2LONG          /**< @old{RB_FIX2LONG} */
      |                      ^
/Users/antonio.facciolo/.rbenv/versions/3.4.8/include/ruby-3.4.0/ruby/internal/arithmetic/long.h:53:22: note: expanded from macro 'RB_FIX2LONG'
   53 | #define RB_FIX2LONG  rb_fix2long          /**< @alias{rb_fix2long} */
      |                      ^
mini_racer_extension.c:677:31: warning: implicit conversion loses integer precision: 'int64_t' (aka 'long long') to 'int' [-Wshorten-64-to-32]
  677 |     deadline = deadline_ms(c->timeout);
      |                ~~~~~~~~~~~ ~~~^~~~~~~
mini_racer_extension.c:758:43: warning: implicit conversion loses integer precision: 'int64_t' (aka 'long long') to 'int' [-Wshorten-64-to-32]
  758 |                 deadline = deadline_ms(c->idle_gc);
      |                            ~~~~~~~~~~~ ~~~^~~~~~~
12 warnings generated.
compiling mini_racer_v8.cc
make: *** [mini_racer_v8.o] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/mini_racer-0.18.1 for inspection.
Results logged to /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/extensions/x86_64-darwin-24/3.4.0/mini_racer-0.18.1/gem_make.out

  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:125:in 'Gem::Ext::Builder.run'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:51:in 'block in Gem::Ext::Builder.make'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:43:in 'Array#each'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:43:in 'Gem::Ext::Builder.make'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/ext_conf_builder.rb:44:in 'Gem::Ext::ExtConfBuilder.build'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:206:in 'Gem::Ext::Builder#build_extension'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:240:in 'block in Gem::Ext::Builder#build_extensions'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:237:in 'Array#each'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/ext/builder.rb:237:in 'Gem::Ext::Builder#build_extensions'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/3.4.0/rubygems/installer.rb:844:in 'Gem::Installer#build_extensions'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/rubygems_gem_installer.rb:111:in 'Bundler::RubyGemsGemInstaller#build_extensions'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/rubygems_gem_installer.rb:30:in 'Bundler::RubyGemsGemInstaller#install'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/source/rubygems.rb:220:in 'Bundler::Source::Rubygems#install'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/installer/gem_installer.rb:55:in 'Bundler::GemInstaller#install'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/installer/gem_installer.rb:17:in 'Bundler::GemInstaller#install_from_spec'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/installer/parallel_installer.rb:133:in 'Bundler::ParallelInstaller#do_install'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/installer/parallel_installer.rb:124:in 'block in Bundler::ParallelInstaller#worker_pool'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/worker.rb:62:in 'Bundler::Worker#apply_func'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/worker.rb:57:in 'block in Bundler::Worker#process_queue'
  <internal:kernel>:168:in 'Kernel#loop'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/worker.rb:54:in 'Bundler::Worker#process_queue'
  /Users/antonio.facciolo/.rbenv/versions/3.4.8/lib/ruby/gems/3.4.0/gems/bundler-2.7.0/lib/bundler/worker.rb:90:in 'block (2 levels) in Bundler::Worker#create_threads'

An error occurred while installing mini_racer (0.18.1), and Bundler cannot continue.

In Gemfile:
  mini_racer

MacOSX 15.7.2
Darwin 24.6.0
Ruby 3.4.8
Bundler 2.6.9 (also tried with 2.7.0)
Rubygems v3.6.7

On the same system, I have tried also the v0.19.1 with Ruby 3.4.7 and it's failing too (I have opened already an issue for that)
At the moment, the only working combination is v0.18.1 with Ruby 3.4.7.