[src/trunk]: src add a note about potential GCC 9->10 build failures

[mrg <mrg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/dab8dd0e4da1
branches:  trunk
changeset: 1020590:dab8dd0e4da1
user:      mrg <mrg%NetBSD.org@localhost>
date:      Sat Apr 17 04:08:32 2021 +0000

description:
add a note about potential GCC 9->10 build failures

diffstat:

 UPDATING |  7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diffs (21 lines):

diff -r 822f69724dfa -r dab8dd0e4da1 UPDATING
--- a/UPDATING  Sat Apr 17 04:07:16 2021 +0000
+++ b/UPDATING  Sat Apr 17 04:08:32 2021 +0000
@@ -1,4 +1,4 @@
-$NetBSD: UPDATING,v 1.317 2021/01/09 20:51:08 rillig Exp $
+$NetBSD: UPDATING,v 1.318 2021/04/17 04:08:32 mrg Exp $
 
 This file (UPDATING) is intended to be a brief reference to recent
 changes that might cause problems in the build process, and a guide for
@@ -19,6 +19,11 @@
 Recent changes:
 ^^^^^^^^^^^^^^^
 
+20210417:
+       GCC 10 was enabled for several platforms.  If builds fail in either
+       tools/gcc or external/gpl/gcc, first try cleaning those objects and
+       removing the $DESTDIR/usr/include/g++ subdirectory.
+
 20201230:
        lint1/ops.c is no longer autogenerated.  If this makes the build
        fail, clean $OBJDIR/tools/*lint* and $OBJDIR/usr.bin/*xlint*.