cli: Support passing --impure

src/cli.rs

@@ -124,6 +124,12 @@ pub fn build_cli(include_internal: bool) -> ClapCommand<'static> {
             .long_help("Passes --show-trace to Nix commands")
             .global(true)
             .takes_value(false))
+        .arg(Arg::new("impure")
+            .long("impure")
+            .help("Allow impure expressions")
+            .long_help("Passes --impure to Nix commands")
+            .global(true)
+            .takes_value(false))
         .arg(Arg::new("color")
             .long("color")
             .help("When to colorize the output")

src/nix/hive/mod.rs

@@ -49,6 +49,9 @@ pub struct Hive {
     /// Whether to pass --show-trace in Nix commands.
     show_trace: bool,
 
+    /// Whether to pass --impure in Nix commands.
+    impure: bool,
+
     meta_config: OnceCell<MetaConfig>,
 }
 
@@ -100,6 +103,7 @@ impl Hive {
             context_dir,
             assets,
             show_trace: false,
+            impure: false,
             meta_config: OnceCell::new(),
         })
     }
@@ -123,11 +127,16 @@ impl Hive {
         self.show_trace = value;
     }
 
+    pub fn set_impure(&mut self, impure: bool) {
+        self.impure = impure;
+    }
+
     /// Returns Nix options to set for this Hive.
     pub fn nix_options(&self) -> NixOptions {
         let mut options = NixOptions::default();
         options.set_show_trace(self.show_trace);
         options.set_pure_eval(self.path.is_flake());
+        options.set_impure(self.impure);
         options
     }
 

src/nix/mod.rs

@@ -197,6 +197,10 @@ impl NixOptions {
         self.pure_eval = pure_eval;
     }
 
+    pub fn set_impure(&mut self, impure: bool) {
+        self.impure = impure;
+    }
+
     pub fn set_builders(&mut self, builders: Option<String>) {
         self.builders = builders;
     }

src/util.rs

@@ -250,6 +250,10 @@ pub async fn hive_from_args(args: &ArgMatches) -> ColmenaResult<Hive> {
                     hive.set_show_trace(true);
                 }
 
+                if args.is_present("impure") {
+                    hive.set_impure(true);
+                }
+
                 return Ok(hive);
             }
 
@@ -273,6 +277,10 @@ pub async fn hive_from_args(args: &ArgMatches) -> ColmenaResult<Hive> {
         hive.set_show_trace(true);
     }
 
+    if args.is_present("impure") {
+        hive.set_impure(true);
+    }
+
     Ok(hive)
 }