feat(error): source location on construct + ReferenceError throws (#5253)

crates/perry-codegen-js/src/emit/exprs.rs

@@ -399,7 +399,7 @@ impl JsEmitter {
                 }
                 self.output.push(')');
             }
-            Expr::NewDynamic { callee, args } => {
+            Expr::NewDynamic { callee, args, .. } => {
                 self.output.push_str("new (");
                 self.emit_expr(callee);
                 self.output.push_str(")(");

crates/perry-codegen-wasm/src/emit/expr/classes.rs

@@ -265,7 +265,7 @@ impl<'a> FuncEmitCtx<'a> {
                 }
                 // If no compiled constructor, just leave the instance handle on stack
             }
-            Expr::NewDynamic { callee, args } => {
+            Expr::NewDynamic { callee, args, .. } => {
                 // Dynamic new — approximate with regular call via mem_call
                 self.emit_frame_begin(func, (args.len() + 1) as u32);
                 self.emit_store_arg(func, 0, callee);

crates/perry-codegen-wasm/src/emit/string_collection.rs

@@ -960,7 +960,7 @@ impl WasmModuleEmitter {
                     self.collect_strings_in_expr(a);
                 }
             }
-            Expr::NewDynamic { callee, args } => {
+            Expr::NewDynamic { callee, args, .. } => {
                 self.collect_strings_in_expr(callee);
                 for a in args {
                     self.collect_strings_in_expr(a);

crates/perry-codegen/src/collectors/escape_check.rs

@@ -659,7 +659,7 @@ pub fn check_escapes_in_expr(
                 check_escapes_in_expr(fi, candidates, classes, escaped);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             check_escapes_in_expr(callee, candidates, classes, escaped);
             for a in args {
                 check_escapes_in_expr(a, candidates, classes, escaped);

crates/perry-codegen/src/collectors/escape_news.rs

@@ -406,7 +406,7 @@ fn collect_used_new_fields_in_expr(
                 collect_used_new_fields_in_expr(arg, non_escaping_news, used);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             collect_used_new_fields_in_expr(callee, non_escaping_news, used);
             for arg in args {
                 collect_used_new_fields_in_expr(arg, non_escaping_news, used);

crates/perry-codegen/src/collectors/refs.rs

@@ -473,7 +473,7 @@ pub fn collect_ref_ids_in_expr(e: &perry_hir::Expr, out: &mut HashSet<u32>) {
         // soft fallback (returns 0.0) and `js_new_function_construct`
         // saw a NaN-zero callee, allocating a class_id=0 empty object
         // with no prototype-method dispatch.
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             walk(callee, out);
             for a in args {
                 walk(a, out);

crates/perry-codegen/src/collectors/this_as_value.rs

@@ -359,7 +359,7 @@ pub fn expr_uses_this_as_value(e: &perry_hir::Expr, fields: &HashSet<String>) ->
             .iter()
             .any(|(_, e)| expr_uses_this_as_value(e, fields)),
         Expr::New { args, .. } => args.iter().any(|a| expr_uses_this_as_value(a, fields)),
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             expr_uses_this_as_value(callee, fields)
                 || args.iter().any(|a| expr_uses_this_as_value(a, fields))
         }

crates/perry-codegen/src/expr/new_dynamic.rs

@@ -67,17 +67,32 @@ fn new_callee_is_primitive_literal(callee: &Expr) -> bool {
 pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
     match expr {
         Expr::New {
-            class_name, args, ..
-        } => lower_new(ctx, class_name, args),
+            class_name,
+            args,
+            byte_offset,
+            ..
+        } => {
+            // #5253: under `--debug-symbols`, attach this `new`'s source
+            // `file:line` so a "X is not a constructor" throw from `lower_new`'s
+            // runtime-construct fallback (or a built-in non-constructor) renders
+            // a location. No-op for resolved user classes (no throw fires).
+            crate::expr::calls::emit_call_location_at(ctx, *byte_offset);
+            lower_new(ctx, class_name, args)
+        }
 
         // `new <callee>(...spread)` — spread-bearing construction. Fold every
         // argument (regular pushed, spread sources expanded via
         // `js_array_like_to_array` + concat) into a single JS array in
         // evaluation order, then dispatch through `js_new_function_construct_apply`
         // which materialises a flat buffer and reuses the full callee-shape
         // dispatch of the non-spread `js_new_function_construct`.
-        Expr::NewDynamicSpread { callee, args } => {
+        Expr::NewDynamicSpread {
+            callee,
+            args,
+            byte_offset,
+        } => {
             use perry_hir::CallArg;
+            let new_byte_offset = *byte_offset;
             let func_double = lower_expr(ctx, callee)?;
             let mut acc_handle = ctx.block().call(I64, "js_array_alloc", &[(I32, "0")]);
             for a in args {
@@ -104,6 +119,8 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                 }
             }
             let args_box = nanbox_pointer_inline(ctx.block(), &acc_handle);
+            // #5253: locate the not-a-constructor throw the apply path can raise.
+            crate::expr::calls::emit_call_location_at(ctx, new_byte_offset);
             let result = ctx.block().call(
                 DOUBLE,
                 "js_new_function_construct_apply",
@@ -155,7 +172,16 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
         //      inspects the callee's NaN tag and dispatches to the right
         //      class constructor. That's a separate followup tracked in
         //      the v0.5.8 changelog.
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic {
+            callee,
+            args,
+            byte_offset,
+        } => {
+            // #5253: source location of this `new` for the not-a-constructor
+            // throws below. `const X: any = undefined; new X()` lowers here
+            // (callee `LocalGet`), so this is what localizes ajv's
+            // `undefined is not a constructor`.
+            let new_byte_offset = *byte_offset;
             // `new <primitive-literal>(…)` is always a `TypeError` — a primitive
             // is never a constructor (`new 1`, `new 1.5`, `new true`, `new null`,
             // `new undefined`, `new "s"`). Number literals lower to a plain `f64`
@@ -168,6 +194,7 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                 for a in args {
                     let _ = lower_expr(ctx, a)?;
                 }
+                crate::expr::calls::emit_call_location_at(ctx, new_byte_offset);
                 return Ok(ctx.block().call(DOUBLE, "js_throw_not_a_constructor", &[]));
             }
 
@@ -499,10 +526,12 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                 let then_synth = Expr::NewDynamic {
                     callee: then_expr.clone(),
                     args: args.clone(),
+                    byte_offset: new_byte_offset,
                 };
                 let else_synth = Expr::NewDynamic {
                     callee: else_expr.clone(),
                     args: args.clone(),
+                    byte_offset: new_byte_offset,
                 };
                 return lower_conditional(ctx, condition, &then_synth, &else_synth);
             }
@@ -570,6 +599,10 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                     .map(|a| lower_expr(ctx, a))
                     .collect::<Result<Vec<_>>>()?;
                 let (args_ptr, args_len) = lower_js_args_array(ctx, &lowered_args);
+                // #5253: locate a not-a-constructor throw from the runtime
+                // construct path (a `LocalGet` callee holding `undefined`, a
+                // non-callable value, etc.).
+                crate::expr::calls::emit_call_location_at(ctx, new_byte_offset);
                 let result = ctx.block().call(
                     DOUBLE,
                     "js_new_function_construct",
@@ -593,6 +626,9 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                 .map(|a| lower_expr(ctx, a))
                 .collect::<Result<Vec<_>>>()?;
             let (args_ptr, args_len) = lower_js_args_array(ctx, &lowered_args);
+            // #5253: locate the not-a-constructor throw for `new <primitive>` /
+            // `new <non-constructor-value>` rejected inside the runtime helper.
+            crate::expr::calls::emit_call_location_at(ctx, new_byte_offset);
             let result = ctx.block().call(
                 DOUBLE,
                 "js_new_function_construct",

crates/perry-codegen/src/lower_call/mod.rs

@@ -115,6 +115,23 @@ pub(crate) use native_table::iter_native_module_table;
 /// 2. `console.log(expr)` where `expr` lowers to a double — emits a
 ///    `js_console_log_number` call and returns `0.0` as the statement value.
 pub(crate) fn lower_call(ctx: &mut FnCtx<'_>, callee: &Expr, args: &[Expr]) -> Result<String> {
+    // #5253: localize the `ReferenceError: X is not defined` thrown by the
+    // unresolved-identifier runtime helper. A bare unresolved identifier
+    // (`module`, winston's stray globals, …) lowers to
+    // `Call { callee: ExternFuncRef("js_global_get_or_throw_unresolved"),
+    // args: [name], byte_offset }` (perry-hir lower_expr). That helper throws a
+    // ReferenceError through `js_referenceerror_new` → `make_stack`, which reads
+    // `CURRENT_CALL_LOCATION`. Emit a `js_set_call_location` from the call's
+    // recorded byte offset (set on `pending_call_offset` by the `Expr::Call`
+    // dispatcher) before lowering the call, so the throw carries `at file:line`.
+    // No-op in the default build; offset 0 (synthesized refs) resolves to none.
+    if let Expr::ExternFuncRef { name, .. } = callee {
+        if name == "js_global_get_or_throw_unresolved" {
+            let off = ctx.strings.pending_call_offset();
+            crate::expr::calls::emit_call_location_at(ctx, off);
+        }
+    }
+
     // #3656: `p.call(thisArg, …)` / `p.apply(thisArg, argsArray)` on a Proxy
     // routes through the proxy's `[[Call]]` (apply trap) rather than reading
     // `.call`/`.apply` off the forwarded target.

crates/perry-codegen/tests/constructor_recursion.rs

@@ -77,6 +77,7 @@ fn module_with_recursive_constructor_return() -> Module {
                 class_name: "RecursiveCtor".to_string(),
                 args: vec![Expr::Bool(false), Expr::LocalGet(11)],
                 type_args: Vec::new(),
+                byte_offset: 0,
             }))],
             else_branch: None,
         }],
@@ -125,6 +126,7 @@ fn module_with_recursive_constructor_return() -> Module {
             class_name: "RecursiveCtor".to_string(),
             args: vec![Expr::Bool(true), Expr::Undefined],
             type_args: Vec::new(),
+            byte_offset: 0,
         })],
         exported_native_instances: Vec::new(),
         exported_func_return_native_instances: Vec::new(),

crates/perry-codegen/tests/typed_shape_descriptor.rs

@@ -110,6 +110,7 @@ fn module_with_new(class: Class) -> Module {
                 class_name,
                 args: Vec::new(),
                 type_args: Vec::new(),
+                byte_offset: 0,
             }))],
             is_async: false,
             is_generator: false,

crates/perry-hir/src/analysis.rs

@@ -1406,7 +1406,7 @@ pub(crate) fn collect_assigned_locals_expr(expr: &Expr, assigned: &mut Vec<Local
             }
         }
         // Dynamic new expression
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             collect_assigned_locals_expr(callee, assigned);
             for arg in args {
                 collect_assigned_locals_expr(arg, assigned);
@@ -2053,7 +2053,7 @@ fn replace_this_in_expr(expr: &mut Expr, this_id: LocalId) {
                 replace_this_in_expr(a, this_id);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             replace_this_in_expr(callee, this_id);
             for a in args {
                 replace_this_in_expr(a, this_id);

crates/perry-hir/src/ir/expr.rs

@@ -304,6 +304,14 @@ pub enum Expr {
         args: Vec<Expr>,
         /// Explicit type arguments (e.g., new Box<number>(42))
         type_args: Vec<Type>,
+        /// #5253: byte offset (`new_expr.span.lo.0`) of this `new` expression
+        /// in its module's source, captured at AST→HIR lowering. Used by
+        /// codegen (under `--debug-symbols`) to attach a `file:line` to the
+        /// runtime "X is not a constructor" TypeError. `0` when unknown
+        /// (synthesized `new` from transforms/intrinsics) — resolves to no
+        /// location, falling back to `<anonymous>`. Mirrors `Call.byte_offset`
+        /// (#5247) and is excluded from stable-hashing.
+        byte_offset: u32,
     },
 
     /// Dynamic new expression (new with non-identifier callee)
@@ -314,6 +322,11 @@ pub enum Expr {
         callee: Box<Expr>,
         /// Arguments to pass to the constructor
         args: Vec<Expr>,
+        /// #5253: source byte offset of the `new` expression — see
+        /// `New::byte_offset`. The `const X: any = undefined; new X()`
+        /// not-a-constructor case lowers here (callee is `LocalGet`), so this
+        /// is the field that localizes ajv's `undefined is not a constructor`.
+        byte_offset: u32,
     },
 
     /// Dynamic `new` with spread arguments — `new <callee>(...args)`.
@@ -325,6 +338,9 @@ pub enum Expr {
     NewDynamicSpread {
         callee: Box<Expr>,
         args: Vec<CallArg>,
+        /// #5253: source byte offset of the `new` expression — see
+        /// `New::byte_offset`.
+        byte_offset: u32,
     },
 
     /// Runtime `new.target` value for ordinary functions.

crates/perry-hir/src/js_transform/cross_module_natives.rs

@@ -905,7 +905,7 @@ pub fn fix_native_instance_expr(
                 fix_native_instance_expr(arg, native_instances, local_id_instances);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             fix_native_instance_expr(callee, native_instances, local_id_instances);
             for arg in args {
                 fix_native_instance_expr(arg, native_instances, local_id_instances);

crates/perry-hir/src/js_transform/imports.rs

@@ -706,7 +706,7 @@ pub fn transform_expr(
         }
 
         // Dynamic new expressions - may be for JS classes (e.g., new ObjectId(str))
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             // Transform the callee first
             transform_expr(callee, js_imports, extern_func_to_js, local_name_to_js, tracker);
 

crates/perry-hir/src/lower/closure_analysis.rs

@@ -246,7 +246,7 @@ fn widen_mutable_captures_expr(
                 widen_mutable_captures_expr(arg, scope_mutable);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             widen_mutable_captures_expr(callee, scope_mutable);
             for arg in args {
                 widen_mutable_captures_expr(arg, scope_mutable);
@@ -554,7 +554,7 @@ fn collect_closure_assigned_expr(expr: &Expr, out: &mut std::collections::HashSe
                 collect_closure_assigned_expr(arg, out);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             collect_closure_assigned_expr(callee, out);
             for arg in args {
                 collect_closure_assigned_expr(arg, out);
@@ -1281,7 +1281,7 @@ fn collect_closure_assigned_in_body_expr(
                 collect_closure_assigned_in_body_expr(arg, out);
             }
         }
-        Expr::NewDynamic { callee, args } => {
+        Expr::NewDynamic { callee, args, .. } => {
             collect_closure_assigned_in_body_expr(callee, out);
             for arg in args {
                 collect_closure_assigned_in_body_expr(arg, out);

crates/perry-hir/src/lower/expr_call/globals.rs

@@ -137,6 +137,7 @@ pub(super) fn try_global_builtins(
                     class_name: "Array".to_string(),
                     args,
                     type_args: Vec::new(),
+                    byte_offset: 0,
                 }));
             }
             "isNaN" => {

crates/perry-hir/src/lower/expr_call/native_module.rs

@@ -1172,6 +1172,7 @@ pub(super) fn try_native_module_methods(
                                                 class_name: cls_name,
                                                 args: new_args,
                                                 type_args: vec![],
+                                                byte_offset: 0,
                                             }));
                                         }
                                     }