4 files changed, 29 insertions, 5 deletions
diff --git a/tvix/eval/src/compiler/attrs.rs b/tvix/eval/src/compiler/attrs.rs
index d6bcfa5109..864cc2cb3d 100644
--- a/tvix/eval/src/compiler/attrs.rs
+++ b/tvix/eval/src/compiler/attrs.rs
@@ -30,7 +30,11 @@ impl Compiler<'_, '_> {
     /// 3. Attribute sets can (optionally) be recursive.
     pub(super) fn compile_attr_set(&mut self, slot: LocalIdx, node: ast::AttrSet) {
         if node.rec_token().is_some() {
-            todo!("recursive attribute sets are not yet implemented")
+            let span = self.span_for(&node);
+            self.emit_warning(
+                span,
+                WarningKind::NotImplemented("recursive attribute sets are not yet implemented"),
+            );
         }
 
         // Open a scope to track the positions of the temporaries used
diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs
index 3e8a6aefd7..627994eaf4 100644
--- a/tvix/eval/src/compiler/mod.rs
+++ b/tvix/eval/src/compiler/mod.rs
@@ -187,7 +187,10 @@ impl Compiler<'_, '_> {
             // their value on the stack.
             ast::Expr::Paren(paren) => self.compile(slot, paren.expr().unwrap()),
 
-            ast::Expr::LegacyLet(_) => todo!("legacy let"),
+            ast::Expr::LegacyLet(_) => {
+                let span = self.span_for(&expr);
+                self.emit_error(span, ErrorKind::NotImplemented("legacy let syntax"));
+            }
 
             ast::Expr::Root(_) => unreachable!("there cannot be more than one root"),
             ast::Expr::Error(_) => unreachable!("compile is only called on validated trees"),
@@ -238,7 +241,14 @@ impl Compiler<'_, '_> {
             buf
         } else {
             // TODO: decide what to do with findFile
-            todo!("other path types (e.g. <...> lookups) not yet implemented")
+            let span = self.span_for(&node);
+            self.emit_error(
+                span,
+                ErrorKind::NotImplemented(
+                    "other path types (e.g. <...> lookups) not yet implemented",
+                ),
+            );
+            return;
         };
 
         // TODO: Use https://github.com/rust-lang/rfcs/issues/2208
@@ -622,7 +632,12 @@ impl Compiler<'_, '_> {
             };
 
             if path.len() != 1 {
-                todo!("nested bindings in let expressions :(")
+                let span = self.span_for(&entry);
+                self.emit_error(
+                    span,
+                    ErrorKind::NotImplemented("nested bindings in let expressions :("),
+                );
+                continue;
             }
 
             let idx = self.declare_local(&entry.attrpath().unwrap(), path.pop().unwrap());
diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs
index ad4acd479e..b87555d06d 100644
--- a/tvix/eval/src/errors.rs
+++ b/tvix/eval/src/errors.rs
@@ -58,6 +58,11 @@ pub enum ErrorKind {
     /// An error occured while forcing a thunk, and needs to be
     /// chained up.
     ThunkForce(Box<Error>),
+
+    /// Tvix internal warning for features triggered by users that are
+    /// not actually implemented yet, and without which eval can not
+    /// proceed.
+    NotImplemented(&'static str),
 }
 
 #[derive(Clone, Debug)]
diff --git a/tvix/eval/src/warnings.rs b/tvix/eval/src/warnings.rs
index 3bae2554cf..b37d0fc918 100644
--- a/tvix/eval/src/warnings.rs
+++ b/tvix/eval/src/warnings.rs
@@ -9,7 +9,7 @@ pub enum WarningKind {
     ShadowedGlobal(&'static str),
 
     /// Tvix internal warning for features triggered by users that are
-    /// not actually implemented yet.
+    /// not actually implemented yet, but do not cause runtime failures.
     NotImplemented(&'static str),
 }