4 files changed, 13 insertions, 16 deletions
diff --git a/tvix/derivation/src/derivation.rs b/tvix/derivation/src/derivation.rs
index 54e0bbf82ec2..d1f46de8c5ee 100644
--- a/tvix/derivation/src/derivation.rs
+++ b/tvix/derivation/src/derivation.rs
@@ -3,6 +3,7 @@ use crate::output::{Hash, Output};
 use crate::write;
 use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256};
+use std::collections::BTreeSet;
 use std::{collections::BTreeMap, fmt, fmt::Write};
 use tvix_store::nixbase32::NIXBASE32;
 use tvix_store::store_path::{ParseStorePathError, StorePath, STORE_DIR};
@@ -18,7 +19,7 @@ pub struct Derivation {
     pub environment: BTreeMap<String, String>,
 
     #[serde(rename = "inputDrvs")]
-    pub input_derivations: BTreeMap<String, Vec<String>>,
+    pub input_derivations: BTreeMap<String, BTreeSet<String>>,
 
     #[serde(rename = "inputSrcs")]
     pub input_sources: Vec<String>,
@@ -173,13 +174,14 @@ impl Derivation {
                 hasher.finalize()
             }
             None => {
-                let mut replaced_input_derivations: BTreeMap<String, Vec<String>> = BTreeMap::new();
+                let mut replaced_input_derivations: BTreeMap<String, BTreeSet<String>> =
+                    BTreeMap::new();
 
                 // For each input_derivation, look up the replacement.
                 for (drv_path, input_derivation) in &self.input_derivations {
                     replaced_input_derivations.insert(
                         fn_get_drv_replacement(drv_path).to_string(),
-                        input_derivation.to_vec(),
+                        input_derivation.clone(),
                     );
                 }
 
diff --git a/tvix/derivation/src/tests/mod.rs b/tvix/derivation/src/tests/mod.rs
index cb98a27cdfe4..bd5d9f34cb12 100644
--- a/tvix/derivation/src/tests/mod.rs
+++ b/tvix/derivation/src/tests/mod.rs
@@ -1,5 +1,6 @@
 use crate::derivation::Derivation;
 use crate::output::{Hash, Output};
+use std::collections::BTreeSet;
 use std::fs::File;
 use std::io::Read;
 use std::path::Path;
@@ -272,9 +273,10 @@ fn output_path_construction() {
     );
 
     // assemble foo input_derivations
-    foo_drv
-        .input_derivations
-        .insert(bar_drv_path.to_absolute_path(), vec!["out".to_string()]);
+    foo_drv.input_derivations.insert(
+        bar_drv_path.to_absolute_path(),
+        BTreeSet::from(["out".to_string()]),
+    );
 
     // calculate foo output paths
     let foo_calc_result = foo_drv.calculate_output_paths(
diff --git a/tvix/derivation/src/validate.rs b/tvix/derivation/src/validate.rs
index eda0457ae564..5335f43636d3 100644
--- a/tvix/derivation/src/validate.rs
+++ b/tvix/derivation/src/validate.rs
@@ -50,21 +50,13 @@ impl Derivation {
                 );
             }
 
-            for (i, output_name) in output_names.iter().enumerate() {
+            for output_name in output_names.iter() {
                 if output_name.is_empty() {
                     bail!(
                         "output name entry for {} may not be empty",
                         input_derivation_path
                     )
                 }
-                // if i is at least 1, peek at the previous element to ensure output_names are sorted.
-                if i > 0 && (output_names[i - 1] >= *output_name) {
-                    bail!(
-                        "invalid input derivation output order: {} < {}",
-                        output_name,
-                        output_names[i - 1],
-                    );
-                }
             }
         }
 
diff --git a/tvix/derivation/src/write.rs b/tvix/derivation/src/write.rs
index 842b2c4ab6ad..8e9cdfcccaf6 100644
--- a/tvix/derivation/src/write.rs
+++ b/tvix/derivation/src/write.rs
@@ -1,5 +1,6 @@
 use crate::output::Output;
 use crate::string_escape::escape_string;
+use std::collections::BTreeSet;
 use std::{collections::BTreeMap, fmt, fmt::Write};
 
 pub const DERIVATION_PREFIX: &str = "Derive";
@@ -84,7 +85,7 @@ pub fn write_outputs(
 
 pub fn write_input_derivations(
     writer: &mut impl Write,
-    input_derivations: &BTreeMap<String, Vec<String>>,
+    input_derivations: &BTreeMap<String, BTreeSet<String>>,
 ) -> Result<(), fmt::Error> {
     writer.write_char(COMMA)?;
     writer.write_char(BRACKET_OPEN)?;