Re: [Tinycc-devel] __attribute__((constructor)) not getting called

[Michael Matz]

Hello,

On Sat, 1 Oct 2022, Liam Wilson wrote:

> Note __attribute__((constructor)) has been stripped off bar and not foo.

Yep, that's the glibc headers defining __attribute__ away ...

> Digging a bit further, it seems to be due to sys/cdefs.h (which is
> included by string.h and many other standard headers). In sys/cdefs.h
> I found this:

... as you found out.

> Is there a work around for this issue? I can define __GNUC__ but 
> presumably that may cause other issues?

The work-around is to use the other form of attribute: __attribute(foo)
(note the missing suffix of '__').  That's still in the implementation 
namespace and not defined away by glibc.

The other work-around would be to '#undef __attribute__' after all glibc 
headers are included.  As <sys/cdefs.h> (on glibc!) also has header guards 
you might also get away with this, as first directives in the .c files:

  #include <sys/cdefs.h>
  #undef __attribute__

as the following includes, even if they include <sys/cdefs.h> again, won't 
parse its content again.  As TCC ignores unknown attributes that should 
work fine for the decls in the glibc headers as well.


Ciao,
Michael.