Zig fails to build

[svmhdvn]

Describe the bug
nixpkgs.zig fails to build on nixpkgs master

To Reproduce
Steps to reproduce the behavior:

1. nix-build --no-out-link -A zig

Additional context
Terminal output

Scanning dependencies of target zig0
[ 98%] Building CXX object CMakeFiles/zig0.dir/src/main.cpp.o
[ 98%] Building CXX object CMakeFiles/zig0.dir/src/stage2.cpp.o
[ 99%] Linking CXX executable zig0
[ 99%] Built target zig0
Scanning dependencies of target zig_build_libstage2
: CommandLine Error: Option 'polly' registered more than once!
LLVM ERROR: inconsistency in registered CommandLine options
make[2]: *** [CMakeFiles/zig_build_libstage2.dir/build.make:77: CMakeFiles/zig_build_libstage2] Error 1
make[1]: *** [CMakeFiles/Makefile2:252: CMakeFiles/zig_build_libstage2.dir/all] Error 2
make: *** [Makefile:150: all] Error 2
builder for '/nix/store/bix9iqj77x932pzvlwdn5f8zhrx7qifs-zig-0.6.0.drv' failed with exit code 2
error: build of '/nix/store/bix9iqj77x932pzvlwdn5f8zhrx7qifs-zig-0.6.0.drv' failed

Notify maintainers
@andrewrk

Metadata

• system: "x86_64-linux"
• host os: Linux 5.4.54, NixOS, 20.09pre236419.a45f68ccac4 (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.7
• channels(root): "nixos-20.09pre236419.a45f68ccac4"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

[marsam]

addressed by #94559