ruby/ruby-dev: Failed to install gem racc

OpenWrt R21.8.6

I have installed ruby and ruby-dev packages, and gcc, and gem install normal(no ext) gems success. But failed to install gem which need build ext， for example:

gem install racc

root@OpenWrt:~/rbtemp# gem install racc
Building native extensions. This could take a while...
ERROR:  Error installing racc:
	ERROR: Failed to build gem native extension.

    current directory: /usr/lib/ruby/gems/3.0/gems/racc-1.6.0/ext/racc/cparse
/usr/bin/ruby -I /usr/lib/ruby/3.0 -r ./siteconf20221109-30543-9inmjv.rb extconf.rb
checking for rb_block_call()... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/usr/bin/$(RUBY_BASE_NAME)
/usr/lib/ruby/3.0/mkmf.rb:471:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.

	from /usr/lib/ruby/3.0/mkmf.rb:567:in `try_link0'
	from /usr/lib/ruby/3.0/mkmf.rb:585:in `try_link'
	from /usr/lib/ruby/3.0/mkmf.rb:797:in `try_func'
	from /usr/lib/ruby/3.0/mkmf.rb:1086:in `block in have_func'
	from /usr/lib/ruby/3.0/mkmf.rb:974:in `block in checking_for'
	from /usr/lib/ruby/3.0/mkmf.rb:361:in `block (2 levels) in postpone'
	from /usr/lib/ruby/3.0/mkmf.rb:331:in `open'
	from /usr/lib/ruby/3.0/mkmf.rb:361:in `block in postpone'
	from /usr/lib/ruby/3.0/mkmf.rb:331:in `open'
	from /usr/lib/ruby/3.0/mkmf.rb:357:in `postpone'
	from /usr/lib/ruby/3.0/mkmf.rb:973:in `checking_for'
	from /usr/lib/ruby/3.0/mkmf.rb:1085:in `have_func'
	from extconf.rb:6:in `'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /usr/lib/ruby/gems/3.0/extensions/aarch64-linux/3.0/racc-1.6.0/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /usr/lib/ruby/gems/3.0/gems/racc-1.6.0 for inspection.
Results logged to /usr/lib/ruby/gems/3.0/extensions/aarch64-linux/3.0/racc-1.6.0/gem_make.out

I did some debug in /usr/lib/ruby/3.0/mkmf.rb

                                                      
  def have_devel?
    unless defined? $have_devel
      $have_devel = true
      $have_devel = try_link(MAIN_DOES_NOTHING)
    end
    $have_devel
  end               
                    
  def try_do(src, command, *opts, &b)
    unless have_devel?
      raise <<MSG
The compiler failed to generate an executable file.
You have to install development tools first.
MSG                                                                
    end    
    begin            
      src = create_tmpsrc(src, &b)
      xsystem(command, *opts)
    ensure    
      log_src(src)
    end
  end

Got used build command :

aarch64-openwrt-linux-musl-gcc -o conftest -I/usr/include/ruby-3.0/aarch64-linux-gnu -I/usr/include/ruby-3.0/ruby/backward -I/usr/include/ruby-3.0 -I. -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/usr/include -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/include/fortify -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/include -I/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libiconv-stub/include -I/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libintl-stub/include    -Os -pipe -mcpu=cortex-a53 -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/ruby-3.0.4=ruby-3.0.4 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -I/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libiconv-stub/include -I/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libintl-stub/include  -fPIC conftest.c  -L. -L/usr/lib -L. -L/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/usr/lib -L/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib -znow -zrelro -L/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libiconv-stub/lib -Wl,-rpath-link=/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libiconv-stub/lib -L/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libintl-stub/lib -Wl,-rpath-link=/builder/shared-workdir/build/sdk/staging_dir/target-aarch64_cortex-a53_musl/usr/lib/libintl-stub/lib -L/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/ruby-3.0.4  -fstack-protector-strong -rdynamic -Wl,-export-dynamic -Wl,--no-as-needed     -lruby  -lm   -lc

@luizluca

Start with the reported gem install racc failure on OpenWrt R21.8.6 and inspect the referenced /usr/lib/ruby/3.0/mkmf.rb behavior. Review the generated mkmf.log, gem_make.out, extconf.rb, and compiler command to identify why the native extension cannot build; done would require a confirmed diagnosis and an agreed repository change.