Unable to build dkms package for nvidia driver

There seems to be a mismatch between the compiler I have installed and the compiler that the build script is expecting; my build log is full of:

make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-mmap.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-i2c.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-p2p.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-pat.o] Error 1
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-procfs.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-vm.o] Error 1
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-usermap.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/nv-vtophys.o] Error 1
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/os-interface.o] Error 1
make[2]: *** [scripts/Makefile.build:286: /var/lib/dkms/nvidia-srv/460.73.01/build/nvidia/os-mlock.o] Error 1

It looks like the problem may be that I have both clang and gcc installed:

jshagam@feldspar:~$ gcc --version
gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

jshagam@feldspar:~$ cc --version
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

The nvidia-dkms Makefile should probably be fixed to use gcc instead of cc, since these appear to be gcc-specific compiler flags.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: nvidia-dkms-460-server 460.73.01-0ubuntu0.20.04.1
ProcVersionSignature: Ubuntu 5.8.0-50.56~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-50-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
Date: Tue Jun 1 10:40:04 2021
InstallationDate: Installed on 2021-03-25 (67 days ago)
InstallationMedia: Kubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: nvidia-graphics-drivers-460-server
UpgradeStatus: No upgrade log present (probably fresh install)