Add forward_variables_from() and target() to GN

tools/gn/function_forward_variables_from_unittest.cc

+// Copyright 2015 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/scheduler.h"
+#include "tools/gn/test_with_scope.h"
+
+TEST(FunctionForwardVariablesFrom, List) {
+  Scheduler scheduler;
+  TestWithScope setup;
+
+  // Defines a template and copy the two x and y values out.
+  TestParseInput input(
+    "template(\"a\") {\n"
+    "  forward_variables_from(invoker, [\"x\", \"y\"])\n"
+    "  print(\"$target_name, $x, $y\")\n"
+    "}\n"
+    "a(\"target\") {\n"
+    "  x = 1\n"
+    "  y = 2\n"
+    "}\n");
+
+  ASSERT_FALSE(input.has_error());
+
+  Err err;
+  input.parsed()->Execute(setup.scope(), &err);
+  ASSERT_FALSE(err.has_error()) << err.message();
+
+  EXPECT_EQ("target, 1, 2\n", setup.print_output());
+  setup.print_output().clear();
+}
+
+TEST(FunctionForwardVariablesFrom, Star) {
+  Scheduler scheduler;
+  TestWithScope setup;
+
+  // Defines a template and copy the two x and y values out.
+  TestParseInput input(
+    "template(\"a\") {\n"
+    "  forward_variables_from(invoker, \"*\")\n"
+    "  print(\"$target_name, $x, $y\")\n"
+    "}\n"
+    "a(\"target\") {\n"
+    "  x = 1\n"
+    "  y = 2\n"
+    "}\n");
+
+  ASSERT_FALSE(input.has_error());
+
+  Err err;
+  input.parsed()->Execute(setup.scope(), &err);
+  ASSERT_FALSE(err.has_error()) << err.message();
+
+  EXPECT_EQ("target, 1, 2\n", setup.print_output());
+  setup.print_output().clear();
+}

[Dirk Pranke, 2015/08/03 19:07:20]

Maybe add a test where one of the values isn't defined, and a test or two for
the typechecking errors (single non-star string, non string-or-list)?