difftest: unify num-traits features on cpu to prevent rustc_codegen_spirv.so rebuilds

Author: Firestar99

default.nix

@@ -11,7 +11,7 @@ in with pkgs; stdenv.mkDerivation rec {
   # Allow cargo to download crates (even inside `nix-shell --pure`).
   SSL_CERT_FILE = "${cacert}/etc/ssl/certs/ca-bundle.crt";
 
-  nativeBuildInputs = [ rustup ];
+  nativeBuildInputs = [ rustup spirv-tools ];
   buildInputs = [ cargo-nextest ];
 
   # Runtime dependencies (for the example runners).

tests/difftests/tests/lib/Cargo.toml

@@ -13,6 +13,13 @@ use-compiled-tools = [
     "spirv-builder/use-compiled-tools"
 ]
 
+[dependencies]
+# DO NOT REMOVE
+# These dependencies are needed for feature unification on the cpu target ever since we added `rustc_codegen_spirv` ->
+# `naga` dependency, as naga transitively depends on `num-traits` with a different feature set than we do.
+spirv-std.workspace = true
+glam.workspace = true
+
 [target.'cfg(not(target_arch = "spirv"))'.dependencies]
 spirv-builder.workspace = true
 difftest-types.workspace = true