[parser] Pessimistically assume top-level variables will be assigned.

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3487 matching lines @@
       const i::AstRawString* var_name =
           info->ast_value_factory()->GetOneByteString("arg");
       i::Variable* var = scope->Lookup(var_name);
       CHECK(var->is_used() || !assigned);
       bool is_maybe_assigned = var->maybe_assigned() == i::kMaybeAssigned;
       CHECK_EQ(is_maybe_assigned, assigned);
     }
   }
 }
 
+TEST(MaybeAssignedTopLevel) {
+  i::Isolate* isolate = CcTest::i_isolate();
+  i::HandleScope scope(isolate);
+  LocalContext env;
+  i::Factory* factory = isolate->factory();
+
+  const char* sources[] = {
+      "let foo; function bar() {foo = 42}; ext(bar); ext(foo)",

[marja, 2017/01/16 15:28:07]

Could you add some destructuring test cases which end up declaring foo?

Like let [a, foo] = [0, 0] and so on.

+      "let foo; ext(function() {foo++}); ext(foo)",
+      "let foo = 0; bar = () => --foo; ext(bar); ext(foo)",
+      "let foo; function* bar() {eval(ext)}; ext(bar); ext(foo)",
+  };
+
+  for (unsigned i = 0; i < arraysize(sources); ++i) {
+    i::ScopedVector<char> program(Utf8LengthHelper(sources[i]) + 1);
+    i::SNPrintF(program, "%s", sources[i]);
+    i::Zone zone(isolate->allocator(), ZONE_NAME);
+
+    i::Handle<i::String> source =
+        factory->InternalizeUtf8String(program.start());
+    source->PrintOn(stdout);
+    printf("\n");
+    i::Handle<i::Script> script = factory->NewScript(source);
+
+    for (unsigned allow_lazy = 0; allow_lazy < 2; ++allow_lazy) {
+      for (unsigned module = 0; module < 2; ++module) {
+        std::unique_ptr<i::ParseInfo> info;
+        info = std::unique_ptr<i::ParseInfo>(new i::ParseInfo(&zone, script));
+        info->set_module(module);
+        info->set_allow_lazy_parsing(allow_lazy);
+
+        CHECK(i::parsing::ParseProgram(info.get()));
+        CHECK(i::Compiler::Analyze(info.get()));
+
+        CHECK_NOT_NULL(info->literal());
+        i::Scope* scope = info->literal()->scope();
+        CHECK(!scope->AsDeclarationScope()->was_lazily_parsed());
+        CHECK_NULL(scope->sibling());
+        CHECK(module ? scope->is_module_scope() : scope->is_script_scope());
+
+        const i::AstRawString* var_name =
+            info->ast_value_factory()->GetOneByteString("foo");
+        i::Variable* var = scope->Lookup(var_name);
+        CHECK(var->is_used());
+        CHECK(var->maybe_assigned() == i::kMaybeAssigned);
+      }
+    }
+  }
+}
+
 namespace {
 
 i::Scope* DeserializeFunctionScope(i::Isolate* isolate, i::Zone* zone,
                                    i::Handle<i::JSObject> m, const char* name) {
   i::AstValueFactory avf(zone, isolate->heap()->HashSeed());
   i::Handle<i::JSFunction> f = i::Handle<i::JSFunction>::cast(
       i::JSReceiver::GetProperty(isolate, m, name).ToHandleChecked());
   i::DeclarationScope* script_scope =
       new (zone) i::DeclarationScope(zone, &avf);
   i::Scope* s = i::Scope::DeserializeScopeChain(
@@ skipping 5317 matching lines @@
     DCHECK_NOT_NULL(scope);
     DCHECK_NULL(scope->sibling());
     DCHECK(scope->is_function_scope());
     const i::AstRawString* var_name =
         info.ast_value_factory()->GetOneByteString("my_var");
     i::Variable* var = scope->Lookup(var_name);
     CHECK_EQ(inners[i].ctxt_allocate,
              i::ScopeTestHelper::MustAllocateInContext(var));
   }
 }