Hi Jonathan,

Thank you for your answer.

> No, don't configure in the source directory:
> https://gcc.gnu.org/wiki/FAQ#configure

OK.

> And it hasn't been necessary to run 'make bootstrap' for years, just
> running 'make' does exactly the same thing now.

Actually, "make" works better than "make bootstrap": While "make bootstrap"
fails with the cited internal compiler error while compiling
libgcc/config/libbid/bid128_add.c, "make" runs to completion.
I started both in separated subdirectories and configured with the same
options.

So, if nobody is using "make bootstrap" any more, that explains why I hit
that internal compiler error.

> I don't see this error when building master on x86_64-pc-linux-gnu.
> This might be a local problem, caused by your host compiler, or the
> versions of GMP, MPFR, or MPC, or something else.

You were probably running "make", not "make bootstrap"?

Next, I ran "make -k check". Its output shows 182 failures in various
test suites. What am I supposed to do?
  - Apply common sense and ignore the failures if they don't have an
    apparent relation with my contribution?
  - Repeat the entire build without my patch, and see if I get the same
    182 failures?
  - Submit my patch to gcc-patches@ anyway, attaching the list of failures?

In summary
==========

I think it would greatly help contributors if the wiki page
https://gcc.gnu.org/contribute.html#testing
was modified:
  1) to mention that the build should be done in a subdirectory or sibling
     directory,
  2) to mention that '../configure [options]' should be run (even if, to
     some people, it is obvious),
  3) to mention to run 'make', not 'make bootstrap' — because 'make bootstrap'
     is too fragile,
  4) to mention how to deal with the result of "make -k check".

Bruno