use of ifndef inhibit_libc to disable the contents linux-unwind.h for targets with MD_UNWIND_SUPPORT

[David Daney]

Stephen M. Kenton wrote:
> During the recent discussion about cross compilers I was told "bugs 
> happen", so I went hunting.
> I have been digging into why building a cross compiler dies in different 
> ways for different targets.
> As seen below, the Linux targets which use glibc define 
> MD_UNWIND_SUPPORT and have
> a customized linux-unwind.h file.  However, mips and i386 start and end 
> those files with
> #ifndef inhibit_libc .... #endif statements which disable the entire 
> contents of the file if inhibit_libc is set.
> Those are the only two such targets I can successfully build with 
> inhibit_libc without the use of enable-sjlj-exceptions.

You never state what you are trying to build.  "cross compiler" does not 
really narrow it down.

Also you don't state what errors you are experiencing.

> Is there some reason that every instance of linux-unwind.h should not 
> start and end with those same
> #ifndef inhibit_libc ... #endif  statements?

In the case of mips, I believe that  inhibit_libc is a surrogate for a 
check that signal.h and asm/unistd.h are usable.


>  Or, alternatively, should 
> setting of inhibit_libc force
> a #undef MD_UNWIND_SUPPORT at some suitably central place rather than 
> doing things the
> way that mips and i386 currently handle it?
> 

I think Danial Jacobowitz is probably correct in that the structure 
definitions should just be copied into libgcc so that we are not 
dependent on libc.

David Daney