Re: Sunos4 bootstrap failure, bug in cpp's implicit extern "C" marking

[Zack Weinberg <zack at wolery dot cumb dot org>]

On Wed, Mar 01, 2000 at 02:52:14PM -0500, Kaveh R. Ghazi wrote:
> 	I'm still getting the following error when bootstrapping on
> sunos4 when compiling libstdc++/cinst.cc:
> 
>  >   ../../../egcs-CVS20000229/libstdc++/cinst.cc -o fcomplex.o
>  > In file included from ../../../egcs-CVS20000229/libstdc++/complex:7,
>  >                  from ../../../egcs-CVS20000229/libstdc++/std/complext.cc:28,
>  >                  from ../../../egcs-CVS20000229/libstdc++/cinst.cc:29:
>  > /a/caip/a99/u99/ghazi/gcc-testing/sunos-test/build/gcc/include/math.h:67:
>  > previous declaration of `double hypot (double, double)' with C++ linkage
>  > ../../../egcs-CVS20000229/libstdc++/std/complext.h:314:
>  > conflicts with new declaration with C linkage
>  > make[2]: *** [bigstmp-complx] Error 1
> 
> Note that the "fixed" math.h on sunos4 is giving C++ linkage to its
> functions.  This has been happening since at least as far back as:
> 
> http://gcc.gnu.org/ml/gcc-bugs/2000-02/msg00142.html
> 
> I thought this would have been fixed with the patch that corrected the
> "in system header" stuff, but its not.
> 
> I looked a bit at the code to do implicit extern "C" on system headers
> and saw this in cpplib.c:output_line_command()
> 
>  >   /* Tell cc1 if following text comes from a system header file.  */
>  >   if (ip->system_header_p)
>  >     {
>  >       CPP_PUTC_Q (pfile, ' ');
>  >       CPP_PUTC_Q (pfile, '3');
>  >     }
>  > #ifndef NO_IMPLICIT_EXTERN_C
>  >   /* Tell cc1plus if following text should be treated as C.  */
>  >   if (ip->system_header_p == 2 && CPP_OPTIONS (pfile)->cplusplus)
>  >     {
>  >       CPP_PUTC_Q (pfile, ' ');
>  >       CPP_PUTC_Q (pfile, '4');
>  >     }
>  > #endif
> 
> For Sunos4, NO_IMPLICIT_EXTERN_C is not defined, so the code above is
> activated and I verified this by looking at cpplib.i.
> 
> When I look at cinst.ii, I see the following line directives for math.h:
> 
> # 1 "/a/caip/a99/u99/ghazi/gcc-testing/sunos-test/build/gcc/include/math.h" 1 3
> # 57 "/a/caip/a99/u99/ghazi/gcc-testing/sunos-test/build/gcc/include/math.h" 2 3
> # 165 "/a/caip/a99/u99/ghazi/gcc-testing/sunos-test/build/gcc/include/math.h" 3
> 
> I see the 3, indicating math.h is a system header, but I don't see a 4
> to indicate implicit extern "C".

Indeed - ip->system_header_p is never set to 2.  I am testing a fix
for this right now, but there are complications.  Should be out
sometime today.

zw