Use new GN features in the build.

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index b88619da6aeb5b424699b6b07303043869d7996b..0782179a37fb6ca3bfd4e0043a4c6ec18846554b 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -604,7 +604,8 @@ if (is_win) {
 # COMPONENT SETUP
 # ==============================================================================
 
-# TODO(brettw) erase this once the built-in "component" function is removed.
+# TODO(brettw) Convert this to being a non-exported variable ('_' prefix) this

[Dirk Pranke, 2015/08/04 18:19:22]

clarify that "this" == "component_mode" ?

+# once ICU's BUILD.gn file is updated to use is_component_build instead.
 if (is_component_build) {
   component_mode = "shared_library"
 } else {
@@ -612,192 +613,14 @@ if (is_component_build) {
 }
 
 template("component") {
-  if (is_component_build) {
-    shared_library(target_name) {
-      # Configs will always be defined since we set_defaults for a component
-      # above. We want to use those rather than whatever came with the nested
-      # shared/static library inside the component.
-      configs = []  # Prevent list overwriting warning.
-      configs = invoker.configs
-
-      # The sources assignment filter will have already been applied when the
-      # code was originally executed. We don't want to apply it again, since
-      # the original target may have override it for some assignments.
-      set_sources_assignment_filter([])
-
-      if (defined(invoker.all_dependent_configs)) {
-        all_dependent_configs = invoker.all_dependent_configs
-      }
-      if (defined(invoker.allow_circular_includes_from)) {
-        allow_circular_includes_from = invoker.allow_circular_includes_from
-      }
-      if (defined(invoker.cflags)) {
-        cflags = invoker.cflags
-      }
-      if (defined(invoker.cflags_c)) {
-        cflags_c = invoker.cflags_c
-      }
-      if (defined(invoker.cflags_cc)) {
-        cflags_cc = invoker.cflags_cc
-      }
-      if (defined(invoker.cflags_objc)) {
-        cflags_objc = invoker.cflags_objc
-      }
-      if (defined(invoker.cflags_objcc)) {
-        cflags_objcc = invoker.cflags_objcc
-      }
-      if (defined(invoker.check_includes)) {
-        check_includes = invoker.check_includes
-      }
-      if (defined(invoker.data)) {
-        data = invoker.data
-      }
-      if (defined(invoker.data_deps)) {
-        data_deps = invoker.data_deps
-      }
-      if (defined(invoker.datadeps)) {
-        datadeps = invoker.datadeps
-      }
-      if (defined(invoker.defines)) {
-        defines = invoker.defines
-      }
-
-      # All shared libraries must have the sanitizer deps to properly link in
-      # asan mode (this target will be empty in other cases).
-      if (defined(invoker.deps)) {
-        deps = invoker.deps + [ "//build/config/sanitizers:deps" ]
-      } else {
-        deps = [
-          "//build/config/sanitizers:deps",
-        ]
-      }
-      if (defined(invoker.forward_dependent_configs_from)) {
-        forward_dependent_configs_from = invoker.forward_dependent_configs_from
-      }
-      if (defined(invoker.include_dirs)) {
-        include_dirs = invoker.include_dirs
-      }
-      if (defined(invoker.ldflags)) {
-        ldflags = invoker.ldflags
-      }
-      if (defined(invoker.lib_dirs)) {
-        lib_dirs = invoker.lib_dirs
-      }
-      if (defined(invoker.libs)) {
-        libs = invoker.libs
-      }
-      if (defined(invoker.output_extension)) {
-        output_extension = invoker.output_extension
-      }
-      if (defined(invoker.output_name)) {
-        output_name = invoker.output_name
-      }
-      if (defined(invoker.public)) {
-        public = invoker.public
-      }
-      if (defined(invoker.public_configs)) {
-        public_configs = invoker.public_configs
-      }
-      if (defined(invoker.public_deps)) {
-        public_deps = invoker.public_deps
-      }
-      if (defined(invoker.sources)) {
-        sources = invoker.sources
-      }
-      if (defined(invoker.testonly)) {
-        testonly = invoker.testonly
-      }
-      if (defined(invoker.visibility)) {
-        visibility = invoker.visibility
-      }
-    }
-  } else {
-    source_set(target_name) {
-      # See above.
-      configs = []  # Prevent list overwriting warning.
-      configs = invoker.configs
-
-      # See above call.
-      set_sources_assignment_filter([])
-
-      if (defined(invoker.all_dependent_configs)) {
-        all_dependent_configs = invoker.all_dependent_configs
-      }
-      if (defined(invoker.allow_circular_includes_from)) {
-        allow_circular_includes_from = invoker.allow_circular_includes_from
-      }
-      if (defined(invoker.cflags)) {
-        cflags = invoker.cflags
-      }
-      if (defined(invoker.cflags_c)) {
-        cflags_c = invoker.cflags_c
-      }
-      if (defined(invoker.cflags_cc)) {
-        cflags_cc = invoker.cflags_cc
-      }
-      if (defined(invoker.cflags_objc)) {
-        cflags_objc = invoker.cflags_objc
-      }
-      if (defined(invoker.cflags_objcc)) {
-        cflags_objcc = invoker.cflags_objcc
-      }
-      if (defined(invoker.check_includes)) {
-        check_includes = invoker.check_includes
-      }
-      if (defined(invoker.data)) {
-        data = invoker.data
-      }
-      if (defined(invoker.data_deps)) {
-        data_deps = invoker.data_deps
-      }
-      if (defined(invoker.datadeps)) {
-        datadeps = invoker.datadeps
-      }
-      if (defined(invoker.defines)) {
-        defines = invoker.defines
-      }
-      if (defined(invoker.deps)) {
-        deps = invoker.deps
-      }
-      if (defined(invoker.forward_dependent_configs_from)) {
-        forward_dependent_configs_from = invoker.forward_dependent_configs_from
-      }
-      if (defined(invoker.include_dirs)) {
-        include_dirs = invoker.include_dirs
-      }
-      if (defined(invoker.ldflags)) {
-        ldflags = invoker.ldflags
-      }
-      if (defined(invoker.lib_dirs)) {
-        lib_dirs = invoker.lib_dirs
-      }
-      if (defined(invoker.libs)) {
-        libs = invoker.libs
-      }
-      if (defined(invoker.output_extension)) {
-        output_extension = invoker.output_extension
-      }
-      if (defined(invoker.output_name)) {
-        output_name = invoker.output_name
-      }
-      if (defined(invoker.public)) {
-        public = invoker.public
-      }
-      if (defined(invoker.public_configs)) {
-        public_configs = invoker.public_configs
-      }
-      if (defined(invoker.public_deps)) {
-        public_deps = invoker.public_deps
-      }
-      if (defined(invoker.sources)) {
-        sources = invoker.sources
-      }
-      if (defined(invoker.testonly)) {
-        testonly = invoker.testonly
-      }
-      if (defined(invoker.visibility)) {
-        visibility = invoker.visibility
-      }
+  target(component_mode, target_name) {
+    forward_variables_from(invoker, "*")
+
+    # All shared libraries must have the sanitizer deps to properly link in
+    # asan mode (this target will be empty in other cases).
+    if (!defined(deps)) {
+      deps = []
     }
+    deps += [ "//build/config/sanitizers:deps" ]
   }
 }