Bug #11426: moving RClass does shows warning even if RClass itself is not used

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: -
• ruby -v: ruby 2.3.0dev (2015-08-10 trunk 51517) [x86_64-linux]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[Hanmac (Hans Mackowiak)]

i got the following warning when i want to build my binding with using ruby from trunk

/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/ruby/ruby.h:827:16: warning: attribute ignored in declaration of ‘struct RClassDeprecated’ [-Wattributes]
 #define RClass RClassDeprecated
                ^
/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/x86_64-linux/ruby/config.h:127:67: note: in definition of macro ‘DEPRECATED_TYPE’
 #define DEPRECATED_TYPE(mesg,x) __attribute__ ((deprecated mesg)) x
                                                                   ^
/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/ruby/ruby.h:829:8: note: in expansion of macro ‘RClass’
 struct RClass {
        ^
/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/ruby/ruby.h:827:16: note: attribute for ‘struct RClassDeprecated’ must follow the ‘struct’ keyword
 #define RClass RClassDeprecated
                ^
/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/x86_64-linux/ruby/config.h:127:67: note: in definition of macro ‘DEPRECATED_TYPE’
 #define DEPRECATED_TYPE(mesg,x) __attribute__ ((deprecated mesg)) x
                                                                   ^
/usr/local/rvm/rubies/ruby-head/include/ruby-2.3.0/ruby/ruby.h:829:8: note: in expansion of macro ‘RClass’
 struct RClass {
        ^

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Feedback

What version of gcc?

[Hanmac (Hans Mackowiak)]

"gcc version 4.9.2 (Ubuntu 4.9.2-10ubuntu13)" shipped with Ubuntu

EDIT: i fixed the warning with doing this:

#define RClass RClassDeprecated
struct DEPRECATED_TYPE(("RClass is internal use only"),
RClass {
struct RBasic basic;
});

but i am unsure for what #define RClass RClassDeprecated is for, because there is no RClassDeprecated ...

[nobu (Nobuyoshi Nakada)]

I've misread as that the warnings are shown when compiling ruby.
What's your binding?
Please explain exact steps to reproduce.

[Hanmac (Hans Mackowiak)]

i am building this:
https://github.com/Hanmac/rwx

the error happen when i do:

cd ext
ruby extconf.rb (there are already the warnings in the mkmf.log)

and when i do

make

then the warning does appear for each object file it builds.

[nobu (Nobuyoshi Nakada)]

OK, g++ does reject __attribute__ between struct and a name, while gcc allows.

$ cat a.c
__attribute__((deprecated)) struct a;
$ gcc -c a.c
$ g++ -c a.c
a.c:1:36: warning: attribute ignored in declaration of 'struct a' [-Wattributes]
 __attribute__((deprecated)) struct a;
                                    ^
a.c:1:36: note: attribute for 'struct a' must follow the 'struct' keyword

[nobu (Nobuyoshi Nakada)]

• Status changed from Feedback to Closed

Applied in changeset r51621.

---

ruby.h: adjust for g++

• include/ruby/ruby.h (RClass): move __attribute__ after the
  keyword struct for g++. [ruby-core:70297] [Bug #11426]