refactor(nix-compat/store_path): consistently use SP as type param r/8788

We also use S in other places in the same file, but that's for the
string-like references.

SP is now consistently used as the type parameter for StorePath<_> (and
build_output_path) gets support for it).

By being a bit more careful in the order of assignments in nix-compat/
src/derivation, we can nudge the compiler to use the type we want.

Change-Id: Ia7c298e110dff98d3b113d2388674ce9e22b80e8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12590
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: Marijan Petričević <marijan.petricevic94@gmail.com>
Tested-by: BuildkiteCI

1 files changed, 8 insertions, 5 deletions

diff --git a/tvix/nix-compat/src/store_path/utils.rs b/tvix/nix-compat/src/store_path/utils.rs
index 4bfbb72fcdde..3cf3ba06308f 100644
--- a/tvix/nix-compat/src/store_path/utils.rs
+++ b/tvix/nix-compat/src/store_path/utils.rs
@@ -134,11 +134,14 @@ pub fn build_nar_based_store_path<'a>(
 ///
 /// Input-addresed store paths are always derivation outputs, the "input" in question is the
 /// derivation and its closure.
-pub fn build_output_path<'a>(
+pub fn build_output_path<'a, SP>(
     drv_sha256: &[u8; 32],
     output_name: &str,
     output_path_name: &'a str,
-) -> Result<StorePathRef<'a>, Error> {
+) -> Result<StorePath<SP>, Error>
+where
+    SP: std::cmp::Eq + std::ops::Deref<Target = str> + std::convert::From<&'a str>,
+{
     build_store_path_from_fingerprint_parts(
         &(String::from("output:") + output_name),
         drv_sha256,
@@ -156,13 +159,13 @@ pub fn build_output_path<'a>(
 /// bytes.
 /// Inside a StorePath, that digest is printed nixbase32-encoded
 /// (32 characters).
-fn build_store_path_from_fingerprint_parts<'a, S>(
+fn build_store_path_from_fingerprint_parts<'a, SP>(
     ty: &str,
     inner_digest: &[u8; 32],
     name: &'a str,
-) -> Result<StorePath<S>, Error>
+) -> Result<StorePath<SP>, Error>
 where
-    S: std::cmp::Eq + std::ops::Deref<Target = str> + std::convert::From<&'a str>,
+    SP: std::cmp::Eq + std::ops::Deref<Target = str> + std::convert::From<&'a str>,
 {
     let fingerprint = format!(
         "{ty}:sha256:{}:{STORE_DIR}:{name}",