Building gcc 4.6.1 using a later version

["Guillaume Quere" <gquere at ece dot fr>]

Hello,

I've been trying to build gcc 4.6.1 as a toolchain for OpenWRT from gcc 4.8.2 and gcc 4.7.3.

I've had two problems and thought this would be a good place to archive them, since I spent a good deal of time looking for the solution to the second one.


First problem:
 unsigned thread_local : 1;
gtype-desc.c:8829:18: error: subscripted value is neither array nor pointer nor vector
  sizeof (x_rtl[0]),
gtype-desc.c:8948:36: error: subscripted value is neither array nor pointer nor vector
  sizeof (default_target_libfuncs[0]),
gtype-desc.c:9032:31: error: subscripted value is neither array nor pointer nor vector
  sizeof (default_target_rtl[0]),
gtype-desc.c:9053:31: error: subscripted value is neither array nor pointer nor vector
  sizeof (default_target_rtl[0]),
gtype-desc.c:9060:31: error: subscripted value is neither array nor pointer nor vector
  sizeof (default_target_rtl[0]),
gtype-desc.c:9067:31: error: subscripted value is neither array nor pointer nor vector
  sizeof (default_target_rtl[0]),
make[5]: *** [gtype-desc.o] Error 1

It is reported and solved using the patch on 4.6.1 mentioned here:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51969


Second problem:
/somepath/openwrt/build_dir/toolchain-armeb_gcc-4.6.1_uClibc-0.9.32_eabi/gcc-4.6.1/libgcc/../gcc/libgcc2.c: In function '__negdi2':
/somepath/openwrt/build_dir/toolchain-armeb_gcc-4.6.1_uClibc-0.9.32_eabi/gcc-4.6.1/libgcc/../gcc/libgcc2.c:72:1: internal compiler error: Segmentation fault

Is fixed using this patch on 4.6.1: http://gcc.gnu.org/viewcvs/gcc/branches/gcc-4_7-branch/gcc/ira-int.h?r1=191605&r2=191604&pathrev=191605


Fixing these two things, I successfully built 4.6.1 using 4.7.3. Can't say for sure that it'll also work for 4.8.2 but the errors were quite similar, so there's a good chance it will.

Hope this helps someone someday,
GQ