[GN]: Precompiled header support for GCC.

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/scheduler.h"
 #include "tools/gn/target.h"
@@ skipping 443 matching lines @@
                "withpch/obj/build/pch_target.precompile.cc.o\n"
         "\n"
         "build withpch/obj/foo/pch_target.stamp: "
                "stamp withpch/obj/foo/pch_target.input1.o "
                // The precompiled object file was added to the outputs.
                "withpch/obj/build/pch_target.precompile.cc.o\n";
     EXPECT_EQ(pch_win_expected, out.str());
   }
 }
 
+TEST(NinjaBinaryTargetWriter, GCCPrecompiledHeaders) {
+  Err err;
+
+  // This setup's toolchain does not have precompiled headers defined.
+  TestWithScope setup;
+
+  // A precompiled header toolchain.
+  Settings pch_settings(setup.build_settings(), "withpch/");
+  Toolchain pch_toolchain(&pch_settings,
+                          Label(SourceDir("//toolchain/"), "withpch"));
+
+  // Declare a C++ compiler that supports PCH.
+  scoped_ptr<Tool> cxx_tool(new Tool);
+  TestWithScope::SetCommandForTool(
+      "c++ {{source}} {{cflags}} {{cflags_cc}} {{defines}} {{include_dirs}} "
+      "-o {{output}}",
+      cxx_tool.get());
+  cxx_tool->set_outputs(SubstitutionList::MakeForTest(
+      "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o"));
+  cxx_tool->set_precompiled_header_type(Tool::PCH_GCC);
+  pch_toolchain.SetTool(Toolchain::TYPE_CXX, cxx_tool.Pass());
+  pch_toolchain.ToolchainSetupComplete();
+
+  // This target doesn't specify precompiled headers.
+  {
+    Target no_pch_target(&pch_settings,
+                         Label(SourceDir("//foo/"), "no_pch_target"));
+    no_pch_target.set_output_type(Target::SOURCE_SET);
+    no_pch_target.visibility().SetPublic();
+    no_pch_target.sources().push_back(SourceFile("//foo/input1.cc"));
+    no_pch_target.SetToolchain(&pch_toolchain);
+    ASSERT_TRUE(no_pch_target.OnResolved(&err));
+
+    std::ostringstream out;
+    NinjaBinaryTargetWriter writer(&no_pch_target, out);
+    writer.Run();
+
+    const char no_pch_expected[] =
+        "defines =\n"
+        "include_dirs =\n"
+        "cflags =\n"
+        "cflags_cc =\n"
+        "target_output_name = no_pch_target\n"
+        "\n"
+        "build withpch/obj/foo/no_pch_target.input1.o: "
+               "cxx ../../foo/input1.cc\n"
+        "\n"
+        "build withpch/obj/foo/no_pch_target.stamp: "
+               "stamp withpch/obj/foo/no_pch_target.input1.o\n";
+    EXPECT_EQ(no_pch_expected, out.str());
+  }
+
+  // This target specifies PCH.
+  {
+    Target pch_target(&pch_settings,
+                      Label(SourceDir("//foo/"), "pch_target"));
+    pch_target.config_values().set_precompiled_header("build/precompile.h");
+    pch_target.config_values().set_precompiled_source(
+        SourceFile("//build/precompile.h"));
+    pch_target.set_output_type(Target::SOURCE_SET);
+    pch_target.visibility().SetPublic();
+    pch_target.sources().push_back(SourceFile("//foo/input1.cc"));
+    pch_target.SetToolchain(&pch_toolchain);
+    ASSERT_TRUE(pch_target.OnResolved(&err));
+
+    std::ostringstream out;
+    NinjaBinaryTargetWriter writer(&pch_target, out);
+    writer.Run();
+
+    const char pch_gcc_expected[] =
+        "defines =\n"
+        "include_dirs =\n"
+        "cflags =\n"
+        "cflags_cc =\n"
+        "target_output_name = pch_target\n"
+        "\n"
+        // Compile the precompiled source with -x <lang>.
+        "build withpch/obj/build/pch_target.precompile.cc.o: "
+               "cxx ../../build/precompile.h\n"
+        "  cflags_cc = ${cflags_cc} -x c++-header\n"
+        "\n"
+        "build withpch/obj/foo/pch_target.input1.o: "
+               "cxx ../../foo/input1.cc | "
+               // Explicit dependency on the PCH build step.
+               "withpch/obj/build/pch_target.precompile.cc.o\n"
+        "\n"
+        "build withpch/obj/foo/pch_target.stamp: "
+               "stamp withpch/obj/foo/pch_target.input1.o "
+               // The precompiled object file was added to the outputs.
+               "withpch/obj/build/pch_target.precompile.cc.o\n";
+    EXPECT_EQ(pch_gcc_expected, out.str());
+  }
+}
+
 // Should throw an error with the scheduler if a duplicate object file exists.
 // This is dependent on the toolchain's object file mapping.
 TEST(NinjaBinaryTargetWriter, DupeObjFileError) {
   Scheduler scheduler;
 
   TestWithScope setup;
   TestTarget target(setup, "//foo:bar", Target::EXECUTABLE);
   target.sources().push_back(SourceFile("//a.cc"));
   target.sources().push_back(SourceFile("//a.cc"));
 
   EXPECT_FALSE(scheduler.is_failed());
 
   std::ostringstream out;
   NinjaBinaryTargetWriter writer(&target, out);
   writer.Run();
 
   // Should have issued an error.
   EXPECT_TRUE(scheduler.is_failed());
 }