[Bug 255910] lang/ruby26 lang/ruby27: Fix clang 12 -Wcompound-token-split-by-macro warning in ruby.h

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255910

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A commit in branch main references this bug:

URL:
https://cgit.FreeBSD.org/ports/commit/?id=6f95cc52457d9c074ce91cdbd652a782424e41ee

commit 6f95cc52457d9c074ce91cdbd652a782424e41ee
Author:     Dimitry Andric <dim@FreeBSD.org>
AuthorDate: 2021-05-15 17:12:06 +0000
Commit:     Dimitry Andric <dim@FreeBSD.org>
CommitDate: 2021-05-29 14:08:19 +0000

    lang/ruby{26,27}: work around clang 12 -Wcompound-token-split-by-macro
warning

    During an exp-run for llvm 12 (see bug 255570), it turned out that
    several ruby gem extensions do not build with clang 12.0.0, for example
    devel/rubygem-thrift:

    compiling binary_protocol_accelerated.c
    binary_protocol_accelerated.c:404:68: error: '(' and '{' tokens introducing
statement expression appear in different macro expansion contexts
[-Werror,-Wcompound-token-split-by-macro]
      VALUE thrift_binary_protocol_class = rb_const_get(thrift_module,
rb_intern("BinaryProtocol"));
                                                                      
^~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1847:23: note: expanded from macro
'rb_intern'
            __extension__ (RUBY_CONST_ID_CACHE((ID), (str))) : \
                          ^
    binary_protocol_accelerated.c:404:68: note: '{' token is here
      VALUE thrift_binary_protocol_class = rb_const_get(thrift_module,
rb_intern("BinaryProtocol"));
                                                                      
^~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1847:24: note: expanded from macro
'rb_intern'
            __extension__ (RUBY_CONST_ID_CACHE((ID), (str))) : \
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1832:5: note: expanded from macro
'RUBY_CONST_ID_CACHE'
        {                                                   \
        ^

    and similarly www/unit-ruby:

    src/ruby/nxt_ruby.c:242:21: error: '(' and '{' tokens introducing statement
expression appear in different macro expansion contexts
[-Werror,-Wcompound-token-split-by-macro]
        nxt_ruby_call = rb_intern("call");
                        ^~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1847:23: note: expanded from macro
'rb_intern'
            __extension__ (RUBY_CONST_ID_CACHE((ID), (str))) : \
                          ^
    src/ruby/nxt_ruby.c:242:21: note: '{' token is here
        nxt_ruby_call = rb_intern("call");
                        ^~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1847:24: note: expanded from macro
'rb_intern'
            __extension__ (RUBY_CONST_ID_CACHE((ID), (str))) : \
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/local/include/ruby-2.7/ruby/ruby.h:1832:5: note: expanded from macro
'RUBY_CONST_ID_CACHE'
        {                                                   \
        ^

    The gem extensions appear to purposefully compile using -Werror, and
    this new -Wcompound-token-split-by-macro is enabled by default in clang
    12 and later. Of course we could go over all these extensions, and
    either remove -Werror or add -Wno-compound-token-split-by-macro, but
    that seems quite a lot of effort.

    Instead, I have submitted a pull request to ruby's GitHub, which fixes
    this by modifying the main ruby.h header:
    * Add RUBY_CONST_ID_CACHE_NB() (i.e. no-brace) which contains the code
      itself, without any braces
    * RUBY_CONST_ID_CACHE() which uses RUBY_CONST_ID_CACHE_NB(), but puts
      braces around it (so no existing code using this macro breaks)
    * Finally, change rb_intern() so the __extension__ directly creates a
      gcc statement expression, using the RUBY_CONST_ID_CACHE_NB() macro

    Patch this locally in our lang/ruby26 and lang/ruby27 ports for now,
    until upstream manages to get this in.

    Approved by:    maintainer timeout (2 weeks)
    PR:             255910
    MFH:            2021Q2

 lang/ruby26/files/patch-include_ruby_ruby.h (new) | 29 +++++++++++++++++++++++
 lang/ruby27/files/patch-include_ruby_ruby.h (new) | 29 +++++++++++++++++++++++
 2 files changed, 58 insertions(+)

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