[GN]: Precompiled header support for GCC.

tools/gn/ninja_binary_target_writer_unittest.cc

Index: tools/gn/ninja_binary_target_writer_unittest.cc
diff --git a/tools/gn/ninja_binary_target_writer_unittest.cc b/tools/gn/ninja_binary_target_writer_unittest.cc
index 5438c4dc6bd463db230cf98c94ad79bfb30fa81c..fbd21982e7b5329684ae27413bb870a6fc753ad0 100644
--- a/tools/gn/ninja_binary_target_writer_unittest.cc
+++ b/tools/gn/ninja_binary_target_writer_unittest.cc
@@ -461,6 +461,100 @@ TEST(NinjaBinaryTargetWriter, WinPrecompiledHeaders) {
   }
 }
 
+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) {