Reduce input dependencies in GN.

tools/gn/ninja_binary_target_writer_unittest.cc

 // Copyright (c) 2013 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 <sstream>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/ninja_binary_target_writer.h"
 #include "tools/gn/target.h"
 #include "tools/gn/test_with_scope.h"
@@ skipping 107 matching lines @@
         // this will probably fail in the archive tool.)
         "build obj/foo/libstlib.a: alink\n"
         "  ldflags =\n"
         "  libs =\n"
         "  output_extension = \n";
     std::string out_str = out.str();
     EXPECT_EQ(expected, out_str);
   }
 }
 
-TEST(NinjaBinaryTargetWriter, ProductExtension) {
+// This tests that output extension overrides apply, and input dependencies
+// are applied.
+TEST(NinjaBinaryTargetWriter, ProductExtensionAndInputDeps) {
   TestWithScope setup;
   setup.build_settings()->SetBuildDir(SourceDir("//out/Debug/"));
   setup.settings()->set_target_os(Settings::LINUX);
 
+  // An action for our library to depend on.
+  Target action(setup.settings(), Label(SourceDir("//foo/"), "action"));
+  action.set_output_type(Target::ACTION_FOREACH);
+  action.SetToolchain(setup.toolchain());
+  action.OnResolved();
+
   // A shared library w/ the product_extension set to a custom value.
   Target target(setup.settings(), Label(SourceDir("//foo/"), "shlib"));
   target.set_output_type(Target::SHARED_LIBRARY);
   target.set_output_extension(std::string("so.6"));
   target.sources().push_back(SourceFile("//foo/input1.cc"));
   target.sources().push_back(SourceFile("//foo/input2.cc"));
+  target.deps().push_back(LabelTargetPair(&action));
   target.SetToolchain(setup.toolchain());
   target.OnResolved();
 
   std::ostringstream out;
   NinjaBinaryTargetWriter writer(&target, out);
   writer.Run();
 
   const char expected[] =
       "defines =\n"
       "include_dirs =\n"
       "cflags =\n"
       "cflags_c =\n"
       "cflags_cc =\n"
       "cflags_objc =\n"
       "cflags_objcc =\n"
       "root_out_dir = .\n"
       "target_out_dir = obj/foo\n"
       "target_output_name = libshlib\n"
       "\n"
-      "build obj/foo/libshlib.input1.o: cxx ../../foo/input1.cc\n"
-      "build obj/foo/libshlib.input2.o: cxx ../../foo/input2.cc\n"
+      "build obj/foo/shlib.inputdeps.stamp: stamp obj/foo/action.stamp\n"
+      "build obj/foo/libshlib.input1.o: cxx ../../foo/input1.cc"
+        " || obj/foo/shlib.inputdeps.stamp\n"
+      "build obj/foo/libshlib.input2.o: cxx ../../foo/input2.cc"
+        " || obj/foo/shlib.inputdeps.stamp\n"
       "\n"
       "build ./libshlib.so.6: solink obj/foo/libshlib.input1.o "
-          "obj/foo/libshlib.input2.o\n"
+      // The order-only dependency here is stricly unnecessary since the
+      // sources list this as an order-only dep. See discussion in the code
+      // that writes this.
+          "obj/foo/libshlib.input2.o || obj/foo/action.stamp\n"
       "  ldflags =\n"
       "  libs =\n"
       "  output_extension = .so.6\n";
 
   std::string out_str = out.str();
   EXPECT_EQ(expected, out_str);
 }
 
 TEST(NinjaBinaryTargetWriter, EmptyProductExtension) {
   TestWithScope setup;
@@ skipping 32 matching lines @@
       "\n"
       "build ./libshlib.so: solink obj/foo/libshlib.input1.o "
           "obj/foo/libshlib.input2.o\n"
       "  ldflags =\n"
       "  libs =\n"
       "  output_extension = .so\n";
 
   std::string out_str = out.str();
   EXPECT_EQ(expected, out_str);
 }