Targets using implicit extern "C"

[Mark Mitchell]

Joe Buck wrote:

> Right, but you don't need the answer to the question until it's time to
> build libstdc++, and you can't build libstdc++ without a C library.
> So can't the test be deferred until that point?

I don't think that's a good idea.  People build compilers without 
headers frequently, and this really can be sensibly defaulted in the 
configuration, perhaps with a configure option to override.  Also, the 
presence of __cplusplus in some system headers isn't enough to make sure 
that the headers are really C++-aware; I've seen systems with a few such 
headers, but not complete awareness.

The argument that there's no right answer for *-elf seems odd to me.  We 
already make assumptions for *-elf that may not be correct for all 
systems, like how to run static initializers, etc.  We certainly can't 
build libstdc++ without knowing about the target C library.

I'd be willing to consider the argument that this should actually be a 
-f switch, with a default determined by the target triplet.  That would 
make it possible to use a *-elf compiler with different 
headers/libraries that you got from somewhere without having to rebuild 
the compiler, which seems better than any autoconfery.

-- 
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304