Date: Tue, 29 Mar 2011 14:20:30 -0700 From: mdf@FreeBSD.org To: freebsd-hackers <freebsd-hackers@freebsd.org> Subject: Include file search path Message-ID: <AANLkTi=BiUVnzsGg83wwWPHjnTDR=XukhJ3UK6Bd5hvF@mail.gmail.com>
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I thought I knew something about how the compiler looks for include
files, but now I think maybe I don't know much. :-)
So here's what I'm pondering. When I build a library, like e.g. libc,
where do the include files get pulled from? They can't (shouldn't) be
the ones in /usr/include, but I don't see a -nostdinc like for the
kernel. There are -I directives in the Makefile for
-I${.CURDIR}/include -I${.CURDIR}/../../include, etc., but that won't
remove /usr/include from the search path.
I see in the gcc documentation that -I paths are searched before the
standards paths. But isn't the lack of -nostdinc a bug (not just for
libc, but for any library in /usr/src/lib)? It somewhat feels to me
that all of the libraries and binaries in the source distribution
should use -nostdinc and include only from the source distribution
itself. This isn't always an issue, but for source upgrades it seems
crucial, and for a hacker it saves difficulties with having to install
headers before re-building.
Is that the intent, and it's not fully implemented? How badly would
things break if -nostdinc was included in e.g. bsd.lib.mk? (This would
break non-base libraries, yes? But as a thought experiment for the
base, how far off are we?)
Thanks,
matthew
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