feat: rec attrset

evaluator/nixjit_hir/src/lib.rs

@@ -41,7 +41,7 @@ pub trait DowngradeContext {
     fn with_expr<T>(&self, id: ExprId, f: impl FnOnce(&Hir, &Self) -> T) -> T;
 
     /// Provides temporary mutable access to an expression.
-    fn with_expr_mut<T>(&mut self, id: &ExprId, f: impl FnOnce(&mut Hir, &mut Self) -> T) -> T;
+    fn with_expr_mut<T>(&mut self, id: ExprId, f: impl FnOnce(&mut Hir, &mut Self) -> T) -> T;
 }
 
 // The `ir!` macro generates the `Hir` enum and related structs and traits.
@@ -128,7 +128,7 @@ impl Attrs for AttrSet {
             match attr {
                 Attr::Str(ident) => {
                     // If the next attribute is a static string.
-                    if let Some(id) = self.stcs.get(&ident) {
+                    if let Some(&id) = self.stcs.get(&ident) {
                         // If a sub-attrset already exists, recurse into it.
                         ctx.with_expr_mut(id, |expr, ctx| {
                             expr.as_mut()

evaluator/nixjit_hir/src/utils.rs

@@ -4,7 +4,9 @@
 //! They are helpers to the main `Downgrade` trait implementations.
 
 use hashbrown::HashMap;
+use hashbrown::hash_map::Entry;
 
+use nixjit_value::format_symbol;
 use rnix::ast;
 
 use nixjit_error::{Error, Result};
@@ -128,19 +130,22 @@ pub fn downgrade_inherit(
             // If `from` is None, `inherit foo;` becomes `foo = foo;`.
             || Var { sym: ident.clone() }.to_hir(),
             // If `from` is Some, `inherit (from) foo;` becomes `foo = from.foo;`.
-            |expr| {
+            |&expr| {
                 Select {
-                    expr: unsafe { expr.clone() },
+                    expr,
                     attrpath: vec![Attr::Str(ident.clone())],
                     default: None,
                 }
                 .to_hir()
             },
         );
-        if stcs.insert(ident, ctx.new_expr(expr)).is_some() {
-            // TODO: Handle or error on duplicate attribute definitions.
-            todo!()
-        }
+        match stcs.entry(ident) {
+            Entry::Occupied(occupied) => return Err(Error::EvalError(format!(
+                "attribute '{}' already defined",
+                format_symbol(occupied.key())
+            ))),
+            Entry::Vacant(vacant) => vacant.insert(ctx.new_expr(expr))
+        };
     }
     Ok(())
 }