$env.CROSS_GCC = (guix build --target=riscv64-linux-gnu gcc-toolchain)

...
...

checking for working strncmp... yes
configure: updating cache ./config.cache
configure: creating ./config.status
config.status: creating Makefile
config.status: creating testsuite/Makefile
config.status: creating config.h
config.status: executing default commands
make[1]: Leaving directory '/tmp/guix-build-gcc-15.2.0.drv-0/build'
make: *** [Makefile:1063: all] Error 2
error: in phase 'build': uncaught exception:
%exception #<&invoke-error program: "make" arguments: ("-j" "12" "--max-load=12" "CFLAGS=-g0 -O2") exit-status: 2 term-signal: #f stop-signal: #f>
phase `build' failed after 23.4 seconds
command "make" "-j" "12" "--max-load=12" "CFLAGS=-g0 -O2" failed with status 2
build process 14 exited with status 256
builder for `/gnu/store/mpbv8phyypfqx30m5khmv7xbz2xwhy07-gcc-15.2.0.drv' failed with exit code 1
build of /gnu/store/mpbv8phyypfqx30m5khmv7xbz2xwhy07-gcc-15.2.0.drv failed
View build log at '/var/log/guix/drvs/mp/bv8phyypfqx30m5khmv7xbz2xwhy07-gcc-15.2.0.drv.gz'.
cannot build derivation `/gnu/store/jn1n4zqssfcyfr3gjv4sxfb67x743q3v-gcc-toolchain-15.2.0.drv': 1 dependencies couldn't be built
guix build: error: build of `/gnu/store/jn1n4zqssfcyfr3gjv4sxfb67x743q3v-gcc-toolchain-15.2.0.drv' failed