[Mingw-notify] [ mingw-Bugs-1251320 ] gcc ignores __declspec

[SourceForge.net <no...@so...>]

Bugs item #1251320, was opened at 2005-08-03 16:08
Message generated for change (Comment added) made by earnie
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1251320&group_id=2435

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: gcc
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: cfis (cfis)
Assigned to: Danny Smith (dannysmith)
Summary: gcc ignores __declspec

Initial Comment:
I'm using mingw/msys to build an extension for a
windows build of ruby.  The ruby header files have the
following code (from defines.h):

//#undef RUBY_EXTERN
//#if defined _WIN32 && !defined __GNUC__
#if defined _WIN32
# ifndef RUBY_EXPORT
#  define RUBY_EXTERN extern __declspec(dllimport)
# endif
#endif

For the extension to work RUBY_EXTERN needs to be
defined as extern __declspec(dllimport).  However, when
I run this:

gcc my_test.c -U__GNUC__ -I/(..path to ruby.h..)

I get an extension that does not work.  Using the gcc
-E switch to investigate further, I've found that the
preprocessor is defining RUBY_EXTERN as just "extern" -
the __declspec is ignored (yes I've verified this part
of the code is called because I can change it to
anything else and it is picked up by the preprocessor).
 Investigating further, the problem appears to be
somehow related to the !defined __GNUC__ call.  Thus,
if I modify the ruby code to uncomment the __GNUC__
check like below things work:

//#undef RUBY_EXTERN
//#if defined _WIN32  // && !defined __GNUC__
#if defined _WIN32
# ifndef RUBY_EXPORT
#  define RUBY_EXTERN extern __declspec(dllimport)
# endif
#endif

Thus there appears to be something strange going on in
the preprocessor.  Note if you change the code as above
you can run gcc like this, without the undefine.

gcc my_test.c -I/(..path to ruby.h..)

This works fine.

Thanks,

Charlie

------------------------------------------------------------

My setup:

windows xp, sp 2

$ gcc -v
Reading specs from
d:/mingw/bin/../lib/gcc/mingw32/3.4.4/specs
Configured with: ../gcc/configure --with-gcc
--with-gnu-ld --with-gnu-as --host=mingw32
--target=mingw32 --prefix=/mingw --enable-threads
--disable-nls
--enable-languages=c,c++,f77,ada,objc,java
--disable-win32-registry --disable-shared
--enable-sjlj-exceptions --enable-libgcj
--disable-java-awt --without-x --enable-java-gc=boehm
--disable-libgcj-debug --enable-interpreter
--enable-hash-synchronization --enable-libstdcxx-debug
Thread model: win32
gcc version 3.4.4 (mingw special)

$ ld -v
GNU ld version 2.15.94 20050118

Release: MinGW-4.1.0.exe 

$ uname -a
MINGW32_NT-5.1 TRILOBITE 1.0.11(0.46/3/2) 2004-04-30
18:55 i686 unknown

-------------------------------
Simple Ruby extension:

#include "ruby.h"

static int id_push;

static VALUE t_init(VALUE self)
{
	VALUE arr;
	arr = rb_ary_new();
	rb_iv_set(self, "@arr", arr);
	return self;
}

static VALUE t_add(VALUE self, VALUE obj)
{
	VALUE arr;
	arr = rb_iv_get(self, "@arr");
	rb_funcall(arr, id_push, 1, obj);
	return arr;
}

VALUE cTest;

void Init_my_test() {
	cTest = rb_define_class("MyTest", rb_cObject);
	rb_define_method(cTest, "initialize", t_init, 0);
	rb_define_method(cTest, "add", t_add, 1);
	id_push = rb_intern("push");
}

--------------------
To compile (and the resulting error):

$ reimp /c/Development/ruby/lib/msvcrt-ruby18.lib

[creates libmsvcrt-ruby18.a in current directory]

$ gcc -g -c my_test.c
-I/c/Development/ruby/lib/ruby/1.8/i386-mswin32

$gcc -shared my_test.o -o my_test.so -lmsvcrt-ruby18 
 -L. 

$ ruby -C . -e "require 'my_test'"
./my_test.so: wrong argument type Fixnum (expected
Class) (TypeError)
        from
c:/Development/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:21:in
`require'
        from -e:1









----------------------------------------------------------------------

>Comment By: Earnie Boyd (earnie)
Date: 2005-08-03 16:56

Message:
Logged In: YES 
user_id=15438

Have you tried building a MinGW version of the Ruby libraries?

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1251320&group_id=2435