toolchain/54699: netbsd-9 build failure on amd64 in gcc

[dholland%eecs.harvard.edu@localhost]

>Number:         54699
>Category:       toolchain
>Synopsis:       netbsd-9 build failure on amd64 in gcc
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Nov 16 10:15:00 +0000 2019
>Originator:     David Holland
>Release:        NetBSD 9.0_BETA (20191114)
>Organization:
>Environment:
System: NetBSD weatherwax 9.0_BETA NetBSD 9.0_BETA (WEATHERWAX) #2: Thu Nov 14 20:44:52 EST 2019  dholland@weatherwax:/usr/src/sys/arch/amd64/compile/WEATHERWAX amd64
Architecture: x86_64
Machine: amd64
>Description:

Building -9 with a -7 userland (and -9 kernel if that matters) failed
today as follows:

    In file included from min-insn-modes.c:6:0:
    /usr/src/external/gpl3/gcc/dist/gcc/machmode.h:228:8: error: 'CONST_MODE_UNIT_SIZE' does not name a type
     extern CONST_MODE_UNIT_SIZE unsigned char mode_unit_size[NUM_MACHINE_MODES];
	    ^
    /usr/src/external/gpl3/gcc/dist/gcc/machmode.h:372:29: error: 'NUM_INT_N_ENTS' was not declared in this scope
     extern bool int_n_enabled_p[NUM_INT_N_ENTS];
				 ^
    /usr/src/external/gpl3/gcc/dist/gcc/machmode.h:373:38: error: 'NUM_INT_N_ENTS' was not declared in this scope
     extern const int_n_data_t int_n_data[NUM_INT_N_ENTS];
					  ^
    min-insn-modes.c:117:1: error: too many initializers for 'const char* const [87]'
     };
     ^

(followed by more of the same)

I'm sure I've seen this before, but I don't remember when/where and
Google is not helping.

I have checked and I'm reasonably certain the source tree is not
corrupt, and there are no local changes in external/gpl3. The tools
version of gcc seems to have built fine.

>How-To-Repeat:

>Fix:

dunno.