[GN]: Support for loadable modules

tools/gn/functions_target.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 "tools/gn/functions.h"
 
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
@@ skipping 337 matching lines @@
 
 Value RunGroup(Scope* scope,
                const FunctionCallNode* function,
                const std::vector<Value>& args,
                BlockNode* block,
                Err* err) {
   return ExecuteGenericTarget(functions::kGroup, scope, function, args,
                               block, err);
 }
 
+// loadable_module -------------------------------------------------------------
+
+const char kLoadableModule[] = "loadable_module";
+const char kLoadableModule_HelpShort[] =
+    "loadable_module: Declare a loadable module target.";
+const char kLoadableModule_Help[] =
+    "loadable_module: Declare a loadable module target.\n"
+    "\n"
+    "  This target type allows you to create an object file that is (and can\n"
+    "  only be) loaded and unloaded at runtime.\n"
+    "\n"
+    "  A loadable module will be specified on the linker line for targets\n"
+    "  listing the loadable module in its \"deps\". If you don't want this\n"
+    "  (if you don't need to dynamically load the library at runtime), then\n"
+    "  you should use a \"shared_library\" target type instead.\n"
+    "\n"
+    "Variables\n"
+    "\n"
+    CONFIG_VALUES_VARS_HELP
+    DEPS_VARS
+    DEPENDENT_CONFIG_VARS
+    GENERAL_TARGET_VARS;
+
+Value RunLoadableModule(Scope* scope,
+                       const FunctionCallNode* function,
+                       const std::vector<Value>& args,
+                       BlockNode* block,
+                       Err* err) {
+  return ExecuteGenericTarget(functions::kLoadableModule, scope, function, args,
+                              block, err);
+}
+
 // shared_library --------------------------------------------------------------
 
 const char kSharedLibrary[] = "shared_library";
 const char kSharedLibrary_HelpShort[] =
     "shared_library: Declare a shared library target.";
 const char kSharedLibrary_Help[] =
     "shared_library: Declare a shared library target.\n"
     "\n"
     "  A shared library will be specified on the linker line for targets\n"
     "  listing the shared library in its \"deps\". If you don't want this\n"
     "  (say you dynamically load the library at runtime), then you should\n"
-    "  depend on the shared library via \"data_deps\" instead.\n"
+    "  depend on the shared library via \"data_deps\" or, on Darwin\n"
+    "  platforms, use a \"loadable_module\" target type instead.\n"
     "\n"
     "Variables\n"
     "\n"
     CONFIG_VALUES_VARS_HELP
     DEPS_VARS
     DEPENDENT_CONFIG_VARS
     GENERAL_TARGET_VARS;
 
 Value RunSharedLibrary(Scope* scope,
                        const FunctionCallNode* function,
@@ skipping 114 matching lines @@
     "\n"
     "  target(my_type, \"foo\") {\n"
     "    ...\n"
     "  }\n";
 Value RunTarget(Scope* scope,
                 const FunctionCallNode* function,
                 const std::vector<Value>& args,
                 BlockNode* block,
                 Err* err) {
   if (args.size() != 2) {
-    *err = Err(function, "Expected two arguments.",
-               "Dude, try \"gn help target\".");
+    *err = Err(function, "Expected two arguments.", "Try \"gn help target\".");
     return Value();
   }
 
   // The first argument must be a string (the target type). Don't type-check
   // the second argument since the target-specific function will do that.
   if (!args[0].VerifyTypeIs(Value::STRING, err))
     return Value();
   const std::string& target_type = args[0].string_value();
 
   // The rest of the args are passed to the function.
   std::vector<Value> sub_args(args.begin() + 1, args.end());
 
   // Run a template if it is one.
   const Template* templ = scope->GetTemplate(target_type);
   if (templ)
     return templ->Invoke(scope, function, sub_args, block, err);
 
   // Otherwise, assume the target is a built-in target type.
   return ExecuteGenericTarget(target_type.c_str(), scope, function, sub_args,
                               block, err);
 }
 
 }  // namespace functions