refactor(tvix/nix-compat): move build_store_path out of derivation r/6060

This doesn't have anything to do with ATerms, we just happen to be using
the aterm representation of a Derivation as contents.

Moving this into store_path/utils.rs makes these things much cleaner -
Have a build_store_path_from_references function, and a
build_store_path_from_fingerprint helper function that makes use of it.

build_store_path_from_references is invoked from the derivation module
which can be used to calculate the derivation path.

In the derivation module, we also invoke
build_store_path_from_fingerprint during the output path calculation.

Change-Id: Ia8d61a5e8e5d3f396f93593676ed3f5d1a3f1d66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8367
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 0 insertions, 18 deletions

diff --git a/tvix/nix-compat/src/lib.rs b/tvix/nix-compat/src/lib.rs
index ec9ddd1ffa7b..2aac179bcfce 100644
--- a/tvix/nix-compat/src/lib.rs
+++ b/tvix/nix-compat/src/lib.rs
@@ -1,5 +1,3 @@
-use sha2::{Digest, Sha256};
-
 pub mod derivation;
 pub mod nar;
 pub mod nixbase32;
@@ -8,19 +6,3 @@ mod nixhash_algos;
 mod nixhash_with_mode;
 pub mod store_path;
 mod texthash;
-
-/// Nix placeholders (i.e. values returned by `builtins.placeholder`)
-/// are used to populate outputs with paths that must be
-/// string-replaced with the actual placeholders later, at runtime.
-///
-/// The actual placeholder is basically just a SHA256 hash encoded in
-/// cppnix format.
-pub fn hash_placeholder(name: &str) -> String {
-    let digest = {
-        let mut hasher = Sha256::new();
-        hasher.update(format!("nix-output:{}", name));
-        hasher.finalize()
-    };
-
-    format!("/{}", nixbase32::encode(&digest))
-}