__STRICT_ANSI__ "fixes" on STDC_0_IN_SYSTEM_HEADERS (solaris) targets

[Zack Weinberg]

On 10/2/06, Kaveh R. Ghazi <ghazi@caipclassic.rutgers.edu> wrote:
>  > Let's not go down the road of including the target config file in
>  > more places which are not part of the compiler proper - which are
>  > not even inside the gcc directory!
>
> I agree, but I also want to avoid duplicating the info in two places,
> it makes maintenance harder.

I certainly support this too.

>  > I'd like to see this used as an occasion to determine whether we
>  > still need this particular hack, which I have never been fond of.
>
> Which hack?  The STDC_0_IN_SYSTEM_HEADERS hack, or the strict_ansi_*
> fixincludes hacks?

I was thinking STDC_0_IN_SYSTEM_HEADERS, but it can't hurt to audit
the fixincludes hacks too...

>  > If we really still do, the Right Thing would be to add another
>  > undocumented built-in preprocessor macro,
>  > __STDC_0_IN_SYSTEM_HEADERS__ say, which is defined only if
>  > CPP_OPTION(pfile, stdc_0_in_system_headers) is true.
>  > zw
>
> I don't see how this will work given that fixincludes is built with
> the bootstrap compiler in 4.0 and 4.1 which has no notion of your new
> macro __STDC_0_IN_SYSTEM_HEADERS__.

Oh, ugh, you're right.

> Another option might be to use the resulting gcc compiler just built
> and compile an autoconf style check to see whether system headers
> define __STDC__ to 1.  We can create a testcase that fakes being in a
> system header by using those digits in the line number directives
> right?  I forget the format, but I seem to recall one of the trailing
> digits signifies we're in a system header.  Then just see if you can
> compile this:
>
> # fake us into system header land...
> #if __STDC__ - 0 == 0
> #error "STDC_0_IN_SYSTEM_HEADERS"
> #endif

Yeah, this should work.  I *think* you can use #pragma GCC
system_header for this,
and I am not sure why the "- 0" bit is necessary?

zw