Fixes to {} handling in GN.

tools/gn/parse_tree_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/test_with_scope.h"
 
@@ skipping 38 matching lines @@
   result = accessor.Execute(setup.scope(), &err);
   EXPECT_FALSE(err.has_error());
   ASSERT_EQ(Value::INTEGER, result.type());
   EXPECT_EQ(kBValue, result.int_value());
 }
 
 TEST(ParseTree, BlockUnusedVars) {
   TestWithScope setup;
 
   // Printing both values should be OK.
+  //
+  // The crazy template definition here is a way to execute a block without
+  // defining a target. Templates require that both the target_name and the
+  // invoker be used, which is what the assertion statement inside the template
+  // does.
   TestParseInput input_all_used(
-      "{\n"
+      "template(\"foo\") { assert(target_name != 0 && invoker != 0) }\n"
+      "foo(\"a\") {\n"
       "  a = 12\n"
       "  b = 13\n"
       "  print(\"$a $b\")\n"
       "}");
   EXPECT_FALSE(input_all_used.has_error());
 
   Err err;
   input_all_used.parsed()->Execute(setup.scope(), &err);
   EXPECT_FALSE(err.has_error());
 
   // Skipping one should throw an unused var error.
   TestParseInput input_unused(
-      "{\n"
+      "foo(\"a\") {\n"
       "  a = 12\n"
       "  b = 13\n"
       "  print(\"$a\")\n"
       "}");
   EXPECT_FALSE(input_unused.has_error());
 
   input_unused.parsed()->Execute(setup.scope(), &err);
   EXPECT_TRUE(err.has_error());
 
   // Also verify that the unused variable has the correct origin set. The
   // origin will point to the value assigned to the variable (in this case, the
   // "13" assigned to "b".
   EXPECT_EQ(3, err.location().line_number());
   EXPECT_EQ(7, err.location().char_offset());
-
 }
 
 TEST(ParseTree, OriginForDereference) {
   TestWithScope setup;
   TestParseInput input(
       "a = 6\n"
       "get_target_outputs(a)");
   EXPECT_FALSE(input.has_error());
 
   Err err;
@@ skipping 101 matching lines @@
         input.parsed()->AsBlock()->statements()[0]->AsBinaryOp();
     ASSERT_TRUE(binop->right()->AsList());
     const ListNode* list = binop->right()->AsList();
     EXPECT_EQ(3u, list->contents().size());
     auto ranges = list->GetSortRanges();
     ASSERT_EQ(1u, ranges.size());
     EXPECT_EQ(1u, ranges[0].begin);
     EXPECT_EQ(3u, ranges[0].end);
   }
 }