Re: [Tinycc-devel] Trouble on x86-64, not windows, not gcc

[Michael Matz]

Hi,

On Sat, 9 Jul 2016, David Mertens wrote:

> When run on Mac systems, I get errors about "incompatible redefinition of
> 'va_list'".

Is that the message from TCC or from some other compiler?  The other 
compiler should use its own <stdarg.h>, not TCCs version.  If the message 
comes from TCC, what are the two definitions of va_list and where does the 
one not coming from TCCs <stdarg.h> comes from?

(Ultimately the layout of va_list has to be compatible between 
compilers on the same system anyway; it's dictated by the psABI.)

> Looking at the source files involved, I'm pretty sure this occurs on 
> x86-64 systems that are neither Windows nor built with gcc. Such systems 
> include 64-bit Macs and BSDs using clang.

Normal BSDs use the sysv ELF psABI, so better have the same definition of 
va_list like in TCCs <stdarg.h>.  Darwin uses the same layout as sysv as 
well.  What could happen is that there are some (and different) type 
aliases in between va_list and the real struct type.

> It might also occur on Solaris, though I've not received any reports 
> from that system yet.

Solaris as well.

> TCC's handling of variable argument lists are spelled out in stdarg.h, 
> with implementation in libtcc1.c. I think that for 64-bit machines, we 
> should also check for clang, and then use clang-compatible definitions. 
> I think I could just check if __llvm__ and/or __clang__ are defined, and 
> then insert the appropriate definitions. Does this sound right?

Not quite.  The definition of va_list depends on the system, not on the 
compiler.  clang can be used with different systems.  So if anything the 
appropriate define would be something MacOS/Darwin related.

> I'd be happy to work on a solution, but I don't have access to a Mac machine
> or a BSD system. I'm not interested in going through a full-on BSD
> installation at this time, so if anybody knows where I could find a
> pre-canned BSD virtualbox image with working git and cc, I'd be much
> obliged.

You need some Darwin system to properly solve this.  I wonder how you get 
the above error message on Mac if you don't have to Macs?


Ciao,
Michael.