From cd23e139138e42c130e5dd8e4c565392776d0272 Mon Sep 17 00:00:00 2001
From: cs01 <cs01@users.noreply.github.com>
Date: Mon, 13 Apr 2026 22:22:14 -0700
Subject: [PATCH] fix: native compiler segfault on closure-mutation error
 inside functions

---
 package-lock.json                                      |  4 ++--
 src/semantic/closure-mutation-checker.ts               |  6 +++++-
 .../closures/closure-mutation-inside-arrow-body.ts     | 10 ++++++++++
 .../closures/closure-mutation-inside-function.ts       |  9 +++++++++
 4 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 tests/fixtures/closures/closure-mutation-inside-arrow-body.ts
 create mode 100644 tests/fixtures/closures/closure-mutation-inside-function.ts

diff --git a/package-lock.json b/package-lock.json
index 6ec5684e..003b1558 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "chadscript",
-  "version": "0.2.0-beta",
+  "version": "0.3.0-beta",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "chadscript",
-      "version": "0.2.0-beta",
+      "version": "0.3.0-beta",
       "license": "MIT",
       "dependencies": {
         "express": "^5.2.1",
diff --git a/src/semantic/closure-mutation-checker.ts b/src/semantic/closure-mutation-checker.ts
index aab83463..6657800c 100644
--- a/src/semantic/closure-mutation-checker.ts
+++ b/src/semantic/closure-mutation-checker.ts
@@ -97,7 +97,11 @@ class ClosureMutationChecker {
       // Simple-name reassignment after capture is the error we're looking for.
       // Member-access assignments (obj.x = y) don't reassign the binding itself.
       if (capturedNames.indexOf(assign.name) !== -1) {
-        this.reportError(assign.name, assign.loc);
+        // NOTE: `assign.loc` is intentionally not passed here. No AssignmentStatement
+        // creation site in parser-ts/parser-native sets `loc`, so reading `assign.loc`
+        // in the native self-hosted compiler GEPs past the struct and segfaults.
+        // See the PR that introduced this comment for the full root cause.
+        this.reportError(assign.name, undefined);
       }
       this.scanExprForCaptures(assign.value, scopeVarNames, capturedNames);
     } else if (stype === "if") {
diff --git a/tests/fixtures/closures/closure-mutation-inside-arrow-body.ts b/tests/fixtures/closures/closure-mutation-inside-arrow-body.ts
new file mode 100644
index 00000000..1a67b6a7
--- /dev/null
+++ b/tests/fixtures/closures/closure-mutation-inside-arrow-body.ts
@@ -0,0 +1,10 @@
+// @test-compile-error: variable 'x' is captured by a closure but reassigned after capture
+// @test-description: closure mutation detected when assignment is inside the arrow body itself
+function outer() {
+  let x = 0;
+  const g = () => {
+    x = 1;
+  };
+  g();
+}
+outer();
diff --git a/tests/fixtures/closures/closure-mutation-inside-function.ts b/tests/fixtures/closures/closure-mutation-inside-function.ts
new file mode 100644
index 00000000..411915b0
--- /dev/null
+++ b/tests/fixtures/closures/closure-mutation-inside-function.ts
@@ -0,0 +1,9 @@
+// @test-compile-error: variable 'x' is captured by a closure but reassigned after capture
+// @test-description: closure mutation detected inside a function body (not just top-level)
+function outer() {
+  let x = 0;
+  const g = () => x;
+  x = 1;
+  g();
+}
+outer();