From d2cf5603bfe522b4252cc3e4c282c7df435720e2 Mon Sep 17 00:00:00 2001
From: Claude Bot <claude-bot@bun.sh>
Date: Sat, 8 Nov 2025 01:14:57 +0000
Subject: [PATCH] Fix panic when parsing declare global with type annotations
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When parsing TypeScript code with `declare global { ... }` blocks,
identifiers followed by colons (like `TIMER: NodeJS.Timeout;`) were
incorrectly treated as labeled statements instead of type annotations.
This caused the parser to push a `.label` scope during the parse pass,
but when visiting the AST later, arrow functions expected `.function_args`
scopes, resulting in a "Scope mismatch while visiting" panic.

The fix checks if we're in a TypeScript declare context before treating
an identifier followed by a colon as a labeled statement. If we are in
a declare context, we skip the type annotation and return a TypeScript
node instead of creating a label scope.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 src/ast/parseStmt.zig                         | 11 ++++
 test/js/bun/transpiler/declare-global.test.ts | 65 +++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 test/js/bun/transpiler/declare-global.test.ts

diff --git a/src/ast/parseStmt.zig b/src/ast/parseStmt.zig
index 8f946e079b..45c0a0b427 100644
--- a/src/ast/parseStmt.zig
+++ b/src/ast/parseStmt.zig
@@ -1185,6 +1185,17 @@ pub fn ParseStmt(
                 switch (expr.data) {
                     .e_identifier => |ident| {
                         if (p.lexer.token == .t_colon and !opts.hasDecorators()) {
+                            // In TypeScript declare contexts, "identifier: Type" is a type annotation, not a label
+                            if (comptime is_typescript_enabled) {
+                                if (opts.is_typescript_declare) {
+                                    // Skip the colon and type annotation
+                                    try p.lexer.next();
+                                    try p.skipTypeScriptType(.lowest);
+                                    try p.lexer.expectOrInsertSemicolon();
+                                    return p.s(S.TypeScript{}, loc);
+                                }
+                            }
+
                             _ = try p.pushScopeForParsePass(.label, loc);
                             defer p.popScope();
 
diff --git a/test/js/bun/transpiler/declare-global.test.ts b/test/js/bun/transpiler/declare-global.test.ts
new file mode 100644
index 0000000000..5ecff87f7e
--- /dev/null
+++ b/test/js/bun/transpiler/declare-global.test.ts
@@ -0,0 +1,65 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+test("declare global with type annotation should not crash", async () => {
+  using dir = tempDir("declare-global-test", {
+    "test.ts": `
+declare global {
+  TIMER: NodeJS.Timeout;
+}
+
+if (globalThis.TIMER) clearInterval(globalThis.TIMER);
+globalThis.TIMER = setInterval(() => console.log("Started"), 1000);
+
+setTimeout(() => {
+  clearInterval(globalThis.TIMER);
+  console.log("SUCCESS");
+  process.exit(0);
+}, 100);
+`,
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "test.ts"],
+    env: bunEnv,
+    cwd: String(dir),
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).not.toContain("panic");
+  expect(stderr).not.toContain("Scope mismatch");
+  expect(stdout).toContain("SUCCESS");
+  expect(exitCode).toBe(0);
+});
+
+test("declare global with multiple type annotations", async () => {
+  using dir = tempDir("declare-global-multi", {
+    "test.ts": `
+declare global {
+  FOO: string;
+  BAR: number;
+  BAZ: () => void;
+}
+
+console.log("SUCCESS");
+`,
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "test.ts"],
+    env: bunEnv,
+    cwd: String(dir),
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).not.toContain("panic");
+  expect(stderr).not.toContain("Scope mismatch");
+  expect(stdout).toContain("SUCCESS");
+  expect(exitCode).toBe(0);
+});