refactor(nix-compat): use StorePathRef for hash derivation modulo r/7389

Rather than passing strings around, use a StorePathRef.

This makes things a bit more typesafe, and more aligned with what we
want to do in b/264.

Change-Id: Ib7080addf27e7f1a9c8da1d8aaa66744468e3b5a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10633
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

2 files changed, 17 insertions, 18 deletions

diff --git a/tvix/glue/src/builtins/derivation.rs b/tvix/glue/src/builtins/derivation.rs
index 728882af394d..c5ed8ec2fffe 100644
--- a/tvix/glue/src/builtins/derivation.rs
+++ b/tvix/glue/src/builtins/derivation.rs
@@ -434,25 +434,24 @@ pub(crate) mod derivation_builtins {
 
         // Calculate the derivation_or_fod_hash for the current derivation.
         // This one is still intermediate (so not added to known_paths)
-        let derivation_or_fod_hash_tmp =
-            drv.derivation_or_fod_hash(|drv| known_paths.get_hash_derivation_modulo(drv));
+        let derivation_or_fod_hash_tmp = drv.derivation_or_fod_hash(|drv_path| {
+            known_paths.get_hash_derivation_modulo(&drv_path.to_owned())
+        });
 
         // Mutate the Derivation struct and set output paths
         drv.calculate_output_paths(&name, &derivation_or_fod_hash_tmp)
             .map_err(DerivationError::InvalidDerivation)?;
 
-        let derivation_path = drv
+        let drv_path = drv
             .calculate_derivation_path(&name)
             .map_err(DerivationError::InvalidDerivation)?;
 
         // recompute the hash derivation modulo and add to known_paths
-        let derivation_or_fod_hash_final =
-            drv.derivation_or_fod_hash(|drv| known_paths.get_hash_derivation_modulo(drv));
+        let derivation_or_fod_hash_final = drv.derivation_or_fod_hash(|drv_path| {
+            known_paths.get_hash_derivation_modulo(&drv_path.to_owned())
+        });
 
-        known_paths.add_hash_derivation_modulo(
-            derivation_path.to_absolute_path(),
-            &derivation_or_fod_hash_final,
-        );
+        known_paths.add_hash_derivation_modulo(drv_path.clone(), &derivation_or_fod_hash_final);
 
         let mut new_attrs: Vec<(String, NixString)> = drv
             .outputs
@@ -465,7 +464,7 @@ pub(crate) mod derivation_builtins {
                         Some(
                             NixContextElement::Single {
                                 name,
-                                derivation: derivation_path.to_absolute_path(),
+                                derivation: drv_path.to_absolute_path(),
                             }
                             .into(),
                         ),
@@ -478,8 +477,8 @@ pub(crate) mod derivation_builtins {
         new_attrs.push((
             "drvPath".to_string(),
             (
-                derivation_path.to_absolute_path(),
-                Some(NixContextElement::Derivation(derivation_path.to_absolute_path()).into()),
+                drv_path.to_absolute_path(),
+                Some(NixContextElement::Derivation(drv_path.to_absolute_path()).into()),
             )
                 .into(),
         ));
diff --git a/tvix/glue/src/known_paths.rs b/tvix/glue/src/known_paths.rs
index b0a4c0ac7129..626b320ed515 100644
--- a/tvix/glue/src/known_paths.rs
+++ b/tvix/glue/src/known_paths.rs
@@ -8,7 +8,7 @@
 //! This data is required to find the derivation needed to actually trigger the
 //! build, if necessary.
 
-use nix_compat::nixhash::NixHash;
+use nix_compat::{nixhash::NixHash, store_path::StorePath};
 use std::collections::HashMap;
 
 #[derive(Debug, Default)]
@@ -16,26 +16,26 @@ pub struct KnownPaths {
     /// All known derivation or FOD hashes.
     ///
     /// Keys are derivation paths, values is the NixHash.
-    derivation_or_fod_hashes: HashMap<String, NixHash>,
+    derivation_or_fod_hashes: HashMap<StorePath, NixHash>,
 }
 
 impl KnownPaths {
     /// Fetch the opaque "hash derivation modulo" for a given derivation path.
-    pub fn get_hash_derivation_modulo(&self, drv_path: &str) -> NixHash {
+    pub fn get_hash_derivation_modulo(&self, drv_path: &StorePath) -> NixHash {
         // TODO: we rely on an invariant that things *should* have
         // been calculated if we get this far.
         self.derivation_or_fod_hashes[drv_path].clone()
     }
 
-    pub fn add_hash_derivation_modulo<D: ToString>(
+    pub fn add_hash_derivation_modulo(
         &mut self,
-        drv: D,
+        drv_path: StorePath,
         hash_derivation_modulo: &NixHash,
     ) {
         #[allow(unused_variables)] // assertions on this only compiled in debug builds
         let old = self
             .derivation_or_fod_hashes
-            .insert(drv.to_string(), hash_derivation_modulo.to_owned());
+            .insert(drv_path, hash_derivation_modulo.to_owned());
 
         #[cfg(debug_assertions)]
         {