feat(glue/builtins): implement builtins.fetchTree

- Add support for Nix flake references parsing and URL handling
- Most of the implementation resides in the glue module for builtins
- Preserve unrecognized URL parameters when extracting known parameters
- Add comprehensive tests for URL handling
- Fetch eagerly, but block on results only upon evaluating thunk

Change-Id: Ibc09c98c24b470fa321459c9ee32f373454dd0ad

Author: domenkozar

snix/Cargo.lock

@@ -72,7 +72,10 @@ fastcdc = "3.1.0"
 fuse-backend-rs = "0.12.0"
 futures = "0.3.30"
 genawaiter = { version = "0.99.1", default-features = false }
-gix = "0.67.0"
+gix = "0.70.0"
+gix-transport = { version = "0.45.0", features = ["blocking-client"] }
+gix-protocol = "0.45.0"
+gix-url = "0.29.0"
 glob = "0.3.1"
 hex-literal = "0.4.1"
 http = "1.1.0"

snix/Cargo.nix

@@ -130,7 +130,7 @@ The `impl` column indicates implementation status in tvix:
 |---------------|--------|-------|-------|-------|
 | break         | false  | 1     |       | todo  |
 | ceil          | false  | 1     | true  |       |
-| fetchTree     | true   | 1     |       | todo  |
+| fetchTree     | true   | 1     |       |       |
 | floor         | false  | 1     | true  |       |
 | groupBy       | false  | 2     | true  |       |
 | traceVerbose  | false  | 2     |       | todo  |

snix/Cargo.toml

@@ -150,6 +150,11 @@ impl Thunk {
         })))
     }
 
+    #[doc(hidden)]
+    /// Creates a thunk that, when forced, calls the given native function.
+    ///
+    /// This is exposed for internal use by modules that need to create thunks
+    /// that defer evaluation until forced.
     pub fn new_suspended_native(native: Box<dyn Fn() -> Result<Value, ErrorKind>>) -> Self {
         Thunk(Rc::new(RefCell::new(ThunkRepr::Native(SuspendedNative(
             native,

snix/docs/src/eval/builtins.md

@@ -17,6 +17,13 @@ chrono = "0.4.35"
 data-encoding.workspace = true
 futures.workspace = true
 magic.workspace = true
+gix.workspace = true
+gix-url.workspace = true
+gix-transport = { workspace = true, features = [
+    "blocking-client",
+    "http-client",
+] }
+gix-protocol = { workspace = true, features = ["blocking-client"] }
 nix-compat = { path = "../nix-compat", features = ["flakeref"] }
 pin-project.workspace = true
 reqwest = { workspace = true, features = ["rustls-tls-native-roots"] }
@@ -36,6 +43,7 @@ serde_json.workspace = true
 sha2.workspace = true
 sha1.workspace = true
 md-5.workspace = true
+tempfile.workspace = true
 url.workspace = true
 walkdir.workspace = true
 clap.workspace = true