[ast/parsing] Pessimistically assume all top-level variables will be assigned.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index af4aa1013ac7c5dc165a5417a41907bd96621b45..f2fb7d3cae50806d0a1d55f5435cff87a151f446 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -824,6 +824,20 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     }
   }
 
+  // Pessimistically assume that top-level variables will be assigned.
+  //
+  // Top-level variables in a script can be accessed by other scripts or even
+  // become global properties. While this does not apply to top-level variables
+  // in a module (assuming they are not exported), we must still mark these as
+  // assigned because they might be accessed by a lazily parsed top-level
+  // function, which, for efficiency, we preparse without variable tracking.
+  V8_INLINE static void MarkTopLevelVariableAsAssigned(Scope* scope,
+                                                       VariableProxy* proxy) {
+    if (scope->is_script_scope() || scope->is_module_scope()) {
+      proxy->set_is_assigned();
+    }
+  }
+
   // Returns true if we have a binary expression between two numeric
   // literals. In that case, *x will be changed to an expression which is the
   // computed value.