* If NIX_DEBUG is turned on (set to "1"), autoconf configure scripts
  may fail to find the correct preprocessor:

    checking how to run the C preprocessor... /lib/cpp


* When building gcc using a Nix gcc, generated libraries link against
  the libraries of the latter:

    $ ldd /nix/store/3b1d3995c4edbf026be5c73f66f69245-gcc-3.3.3/lib/libstdc++.so
    ...
    libgcc_s.so.1 => /nix/store/1f19e61d1b7051f1131f78b41b2a0e7e-gcc-3.3.2/lib/libgcc_s.so.1 (0x400de000)
    (wrong! should be .../3b1d.../lib/libgcc_s...)
    ...


* In libXt:

/bin/sh ./libtool --mode=compile gcc -DHAVE_CONFIG_H -I. -I. -I.     -DXTHREADS -DXUSE_MTSAFE_API -I/nix/store/aadf0bd4a908da11d14f6538503b8408-libX11-6.2.1/include -I/nix/store/ba366e3b944ead64ec9b0490bb615874-xproto-6.6.1/include   -I./include/X11 -g -O2 -c -o ActionHook.lo `test -f 'ActionHook.c' || echo './'`ActionHook.c
mkdir .libs
 gcc -DHAVE_CONFIG_H -I. -I. -I. -DXTHREADS -DXUSE_MTSAFE_API -I/nix/store/aadf0bd4a908da11d14f6538503b8408-libX11-6.2.1/include -I/nix/store/ba366e3b944ead64ec9b0490bb615874-xproto-6.6.1/include -I./include/X11 -g -O2 -c ActionHook.c  -fPIC -DPIC -o .libs/ActionHook.o
In file included from IntrinsicI.h:55,
                 from ActionHook.c:69:
include/X11/IntrinsicP.h:54:27: X11/Intrinsic.h: No such file or directory


* Then:

 gcc -DHAVE_CONFIG_H -I. -I. -I. -DXTHREADS -DXUSE_MTSAFE_API -I/nix/store/aadf0bd4a908da11d14f6538503b8408-libX11-6.2.1/include -I/nix/store/ba366e3b944ead64ec9b0490bb615874-xproto-6.6.1/include -I./include -I./include/X11 -g -O2 -c ActionHook.c  -fPIC -DPIC -o .libs/ActionHook.o
In file included from IntrinsicI.h:55,
                 from ActionHook.c:69:
include/X11/IntrinsicP.h:202:25: X11/ObjectP.h: No such file or directory

(moved to include/X11; should edit include/Makefile.am)


* Doesn't parse:

{stdenv, fetchurl /* pkgconfig, libX11 */ }:

stdenv.mkDerivation {
  name = "libXi-6.0.1";
  src = fetchurl {
    url = http://freedesktop.org/~xlibs/release/libXi-6.0.1.tar.bz2;
    md5 = "7e935a42428d63a387b3c048be0f2756";
  };
/*  buildInputs = [pkgconfig];
  propagatedBuildInputs = [libX11]; */
}



* Add "exit 0" at the end of configure of rte package.


* Starting at gcc 3.4, all C programs incur a retained dependency on
  gcc through the rpath stored in the executable, even though the
  executable doesn't use against any library in gcc.  The reason is
  that the gcc passes a `-lgcc_s' switch to the linker.  Solution:
  patch the linker so that rpaths are only added for libraries that we
  actually use.