Issue #21659 has been updated by wsfulton (William Fulton). This happens when compiling an EXTENSION. We have always used -Wmissing-field-initializers in our extensions and now they are broken. New Ruby releases really MUST NOT introduce new warnings for extensions which have to include Ruby.h. ---------------------------------------- Bug #21659: rstring.h error: missing initializer for field ‘len’ of ‘struct RString’ [-Werror=missing-field-initializers] starting in ruby-3.3.10 https://bugs.ruby-lang.org/issues/21659#change-115017 * Author: wsfulton (William Fulton) * Status: Feedback * ruby -v: ruby 3.3.10 (2025-10-23 revision 343ea05002) [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- All extensions now have this error when using -Werror -Wmissing-field-initializers: ``` In file included from /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/internal/arithmetic/char.h:29, from /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/internal/arithmetic.h:24, from /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/ruby.h:28, from /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby.h:38, from example_wrap.c:1008: /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/internal/core/rstring.h: In function ‘rbimpl_rstring_getmem’: /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/internal/core/rstring.h:398:16: error: missing initializer for field ‘len’ of ‘struct RString’ [-Werror=missing-field-initializers] 398 | struct RString retval = {RBASIC_INIT}; | ^~~~~~~ /home/runner/.rvm/rubies/ruby-3.3.10/include/ruby-3.3.0/ruby/internal/core/rstring.h:206:10: note: ‘len’ declared here 206 | long len; | ^~~ ``` Can you please test with warnings turned on as this now breaks all extensions that rely on Ruby.h being warning free. Looks like it is due to commit https://github.com/ruby/ruby/commit/5a8d7642168f4ea0d9331fded3033c225bbc36c5 and expect that ```c++ struct RString retval = {RBASIC_INIT}; ``` should have been changed to: ```c++ struct RString retval = {RBASIC_INIT, 0}; ``` in rstring.h as well as all in the actual Ruby code base. -- https://bugs.ruby-lang.org/