On 03/30/11 10:23, Dimitry Andric wrote:
On 2011-03-29 23:20, m...@freebsd.org wrote:
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.

During the bootstrap stage, a copy of gcc (or clang) is built, that has
all default search paths for headers, libraries, etc, set relative to
${WORLDTMP}, usually /usr/obj/usr/src/tmp.

E.g:

$ /usr/obj/usr/src/tmp/usr/bin/gcc -v -E -x c /dev/null -o /dev/null
Using built-in specs.
Target: amd64-undermydesk-freebsd
Configured with: FreeBSD/amd64 system compiler
Thread model: posix
gcc version 4.2.1 20070719  [FreeBSD]
/usr/obj/usr/src/tmp/usr/libexec/cc1 -E -quiet -v -D_LONGLONG /dev/null -o /dev/null
#include "..." search starts here:
#include <...> search starts here:
 /usr/obj/usr/src/tmp/usr/include/gcc/4.2
 /usr/obj/usr/src/tmp/usr/include
End of search list.

and:

$ /usr/obj/usr/src/tmp/usr/bin/gcc -print-search-dirs
install: /usr/obj/usr/src/tmp/usr/libexec/
programs: =/usr/obj/usr/src/tmp/usr/bin/:/usr/obj/usr/src/tmp/usr/bin/:/usr/obj/usr/src/tmp/usr/libexec/:/usr/obj/usr/src/tmp/usr/libexec/:/usr/obj/usr/src/tmp/usr/libexec/
libraries: =/usr/obj/usr/src/tmp/usr/lib/:/usr/obj/usr/src/tmp/usr/lib/

This is a rather nasty hack, though.  If we can make it work, we should
probably try using --sysroot instead, or alternatively, -nostdinc and
adding include dirs by hand.  The same for executable and library search
paths, although I am not sure if there is a way to completely reset
those with the current options.

Since you need to build two compilers anyway (one for the current system, to build the new one, and one to live in the new one, linked against new libraries), I don't see that it's such a nasty hack.
-Nathan
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