I did the following on an up to date Parabola

$ ./autogen.sh
$ ./configure
$ make release -j5

And we end up with:

Building GMP v6.2.1 for host ... ok
Building MPFR v4.1.0 for host ... ok
Building MPC v1.2.1 for host ... ok
Building BINUTILS v2.37 for target ... ok
Building GCC v11.2.0 for target ... failed. Check 'build-i386-elf-GCC/build.log'.
make[3]: *** [Makefile:19: build_gcc] Error 1
make[2]: *** [Makefile:38: build-i386] Error 2
make[1]: *** [util/crossgcc/Makefile.inc:30: crossgcc-i386] Error 2
make[1]: Leaving directory '[...]/coreboot/default'
Error: build/roms: something went wrong
make: *** [Makefile:717: release] Error 1

We then have the log in coreboot/default/util/crossgcc/build-i386-elf-GCC/build.log.

It contains the following:

[...]
gnatgcc -c -O2  -fomit-frame-pointer -m64   -gnatpg -gnatwGUR  -W -Wall -nostdinc -I- -I. -Iada/generated -Iada -Iada/gcc-interface -I../../gcc-11.2.0/gcc/ada -I../../gcc-11.2.0/gcc/ada/gcc-interface -Iada/libgnat -I../../gcc-11.2.0/gcc/ada/libgnat ../../gcc-11.2.0/gcc/ada/sem_attr.adb -o ada/sem_attr.o
sem.adb:59:06: warning: renamed predefined unit is an obsolescent feature (RM J.1) [-gnatwj]
make[1]: *** [../../gcc-11.2.0/gcc/ada/gcc-interface/Make-lang.in:139: ada/sem.o] Error 1
make[1]: *** Waiting for unfinished jobs....
sem_aggr.adb:2063:24: (style) redundant parentheses [-gnatyz]
sem_aggr.adb:2064:35: (style) redundant parentheses [-gnatyz]
make[1]: *** [../../gcc-11.2.0/gcc/ada/gcc-interface/Make-lang.in:139: ada/sem_aggr.o] Error 1
sem_attr.adb:1056:19: warning: unreachable code [enabled by default]
sem_attr.adb:1385:16: warning: unreachable code [enabled by default]
sem_attr.adb:1392:13: warning: unreachable code [enabled by default]
sem_attr.adb:3397:13: warning: unreachable code [enabled by default]
sem_attr.adb:3477:13: warning: unreachable code [enabled by default]
sem_attr.adb:3676:16: warning: unreachable code [enabled by default]
sem_attr.adb:3691:13: warning: unreachable code [enabled by default]
sem_attr.adb:4679:16: warning: unreachable code [enabled by default]
sem_attr.adb:5554:13: warning: unreachable code [enabled by default]
make[1]: *** [../../gcc-11.2.0/gcc/ada/gcc-interface/Make-lang.in:139: ada/sem_attr.o] Error 1
make[1]: Leaving directory '[...]/coreboot/default/util/crossgcc/build-i386-elf-GCC/gcc'
make: *** [Makefile:4409: all-gcc] Error 2

It's probably not very urgent and it might be fixed automatically by updating the Coreboot or crossgcc revision (if we manage to somehow separate crossgcc from coreboot in the build).