Re: libstdc++-v3/std_cstddef.h's #include_next x libg++

[Benjamin Kosnik <bkoz at redhat dot com>]

> More likely to be related with the recent changes I made to the
> top-level configure.in.  We're using mkcheck to find out what are the
> -I flags to be passed to the C++ compiler, but configure.in arranges
> for -I to be replaced with -isystem, since presumably the libstdc++
> headers are all system headers.

Hmm. Shouldn't you be using INCLUDES from libstdc++-v3/src/Makefile.am:

INCLUDES = \
	-D_GNU_SOURCE -nostdinc++ -I$(top_srcdir) \
	$(CSHADOW_INCLUDES) $(LIBIO_INCLUDES) \
	$(CONFIG_INCLUDES) $(TOPLEVEL_INCLUDES)	

This is the canonical include path for libstdc++-v3, not whatever is in 
mkcheck

> See, libstdc++-v3/bits is searched after gcc/include, so #include_next
> doesn't work.  But replacing all occurrences of -isystem with -I, I
> get the order expected by mkcheck:
[snip]
> So, should I stop replacing -I with -isystem in the output of mkcheck,
> in the top-level configure.in?

Yes. Please consider my point above though.

-benjamin