feat: debug thunk location

nix-js/src/codegen.rs

@@ -40,6 +40,7 @@ pub(crate) trait CodegenContext {
     fn get_current_dir(&self) -> &Path;
     fn get_store_dir(&self) -> &str;
     fn get_current_source_id(&self) -> usize;
+    fn get_current_source(&self) -> crate::error::Source;
 }
 
 trait EscapeQuote {
@@ -117,9 +118,19 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Ir {
             Ir::Arg(x) => format!("arg{}", x.inner.0),
             Ir::Let(x) => x.compile(ctx),
             Ir::Select(x) => x.compile(ctx),
-            &Ir::Thunk(Thunk { inner: expr_id, .. }) => {
+            &Ir::Thunk(Thunk {
+                inner: expr_id,
+                span,
+            }) => {
                 let inner = ctx.get_ir(expr_id).compile(ctx);
-                format!("Nix.createThunk(()=>({}),\"expr{}\")", inner, expr_id.0)
+                format!(
+                    "Nix.createThunk(()=>({}),\"expr{} {}:{}:{}\")",
+                    inner,
+                    expr_id.0,
+                    ctx.get_current_source().get_name(),
+                    usize::from(span.start()),
+                    usize::from(span.end())
+                )
             }
             &Ir::ExprRef(ExprRef { inner: expr_id, .. }) => {
                 format!("expr{}", expr_id.0)

nix-js/src/context.rs

@@ -230,6 +230,9 @@ impl CodegenContext for Ctx {
             .checked_sub(1)
             .expect("current_source not set")
     }
+    fn get_current_source(&self) -> crate::error::Source {
+        self.sources.last().expect("current_source not set").clone()
+    }
     fn get_store_dir(&self) -> &str {
         self.store.as_store().get_store_dir()
     }
@@ -322,8 +325,8 @@ impl DowngradeContext for DowngradeCtx<'_> {
         ExprId(self.ctx.irs.len() + self.irs.len() - 1)
     }
 
-    fn maybe_thunk(&mut self, id: ExprId) -> ExprId {
-        let ir = if id.0 < self.ctx.irs.len() {
+    fn get_ir(&self, id: ExprId) -> &Ir {
+        if id.0 < self.ctx.irs.len() {
             self.ctx.irs.get(id.0).expect("unreachable")
         } else {
             self.irs
@@ -331,7 +334,11 @@ impl DowngradeContext for DowngradeCtx<'_> {
                 .expect("ExprId out of bounds")
                 .as_ref()
                 .expect("maybe_thunk called on an extracted expr")
-        };
+        }
+    }
+
+    fn maybe_thunk(&mut self, id: ExprId) -> ExprId {
+        let ir = self.get_ir(id);
         match ir {
             Ir::Builtin(_)
             | Ir::Builtins(_)
@@ -449,7 +456,7 @@ impl DowngradeContext for DowngradeCtx<'_> {
         })
     }
 
-    fn extract_expr(&mut self, id: ExprId) -> Ir {
+    fn extract_ir(&mut self, id: ExprId) -> Ir {
         let local_id = id.0 - self.ctx.irs.len();
         self.irs
             .get_mut(local_id)
@@ -458,7 +465,7 @@ impl DowngradeContext for DowngradeCtx<'_> {
             .expect("extract_expr called on an already extracted expr")
     }
 
-    fn replace_expr(&mut self, id: ExprId, expr: Ir) {
+    fn replace_ir(&mut self, id: ExprId, expr: Ir) {
         let local_id = id.0 - self.ctx.irs.len();
         let _ = self
             .irs

nix-js/src/error.rs

@@ -35,11 +35,7 @@ impl TryFrom<&str> for Source {
 
 impl From<Source> for NamedSource<Arc<str>> {
     fn from(value: Source) -> Self {
-        let name = match value.ty {
-            SourceType::Eval(_) => "«eval»".into(),
-            SourceType::Repl(_) => "«repl»".into(),
-            SourceType::File(path) => path.as_os_str().to_string_lossy().to_string(),
-        };
+        let name = value.get_name();
         NamedSource::new(name, value.src.clone())
     }
 }
@@ -75,6 +71,14 @@ impl Source {
                 .expect("source file must have a parent dir"),
         }
     }
+
+    pub fn get_name(&self) -> String {
+        match &self.ty {
+            SourceType::Eval(_) => "«eval»".into(),
+            SourceType::Repl(_) => "«repl»".into(),
+            SourceType::File(path) => path.as_os_str().to_string_lossy().to_string(),
+        }
+    }
 }
 
 #[derive(Error, Debug, Diagnostic)]

nix-js/src/ir.rs

@@ -28,8 +28,9 @@ pub trait DowngradeContext {
     fn get_sym(&self, id: SymId) -> &str;
     fn lookup(&mut self, sym: SymId, span: TextRange) -> Result<ExprId>;
 
-    fn extract_expr(&mut self, id: ExprId) -> Ir;
-    fn replace_expr(&mut self, id: ExprId, expr: Ir);
+    fn get_ir(&self, id: ExprId) -> &Ir;
+    fn extract_ir(&mut self, id: ExprId) -> Ir;
+    fn replace_ir(&mut self, id: ExprId, expr: Ir);
     fn reserve_slots(&mut self, slots: usize) -> impl Iterator<Item = ExprId> + Clone + use<Self>;
     fn get_current_source(&self) -> Source;
 
@@ -124,7 +125,7 @@ impl AttrSet {
                     // If the next attribute is a static string.
                     if let Some(&id) = self.stcs.get(&ident) {
                         // If a sub-attrset already exists, recurse into it.
-                        let mut ir = ctx.extract_expr(id);
+                        let mut ir = ctx.extract_ir(id);
                         let result = ir
                             .as_mut()
                             .try_unwrap_attr_set()
@@ -139,7 +140,7 @@ impl AttrSet {
                                 )
                             })
                             .and_then(|attrs| attrs._insert(path, name, value, ctx));
-                        ctx.replace_expr(id, ir);
+                        ctx.replace_ir(id, ir);
                         result?;
                     } else {
                         // Create a new sub-attrset because this path doesn't exist yet.

nix-js/src/ir/utils.rs

@@ -405,21 +405,17 @@ where
 
         for (sym, slot) in binding_keys.iter().copied().zip(slots.iter()) {
             if let Some(&expr) = bindings.get(&sym) {
-                ctx.replace_expr(
+                ctx.replace_ir(
                     *slot,
                     Thunk {
                         inner: expr,
-                        // span: ctx.get_span(expr),
-                        // FIXME: span
-                        span: synthetic_span(),
+                        span: ctx.get_ir(expr).span(),
                     }
                     .to_ir(),
                 );
             } else {
-                return Err(Error::downgrade_error(
+                return Err(Error::internal(
                     format!("binding '{}' not found", format_symbol(ctx.get_sym(sym))),
-                    ctx.get_current_source(),
-                    synthetic_span(),
                 ));
             }
         }