Add GN output prefix override and allow empty output extensions.

tools/gn/variables.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/variables.h"
 
 namespace variables {
 
 // Built-in variables ----------------------------------------------------------
 
@@ skipping 1074 matching lines @@
 const char kOutputExtension_HelpShort[] =
     "output_extension: [string] Value to use for the output's file extension.";
 const char kOutputExtension_Help[] =
     "output_extension: Value to use for the output's file extension.\n"
     "\n"
     "  Normally the file extension for a target is based on the target\n"
     "  type and the operating system, but in rare cases you will need to\n"
     "  override the name (for example to use \"libfreetype.so.6\" instead\n"
     "  of libfreetype.so on Linux).\n"
     "\n"
-    "  This value should not include a leading dot. If undefined or empty,\n"
-    "  the default_output_extension specified on the tool will be used.\n"
-    "  The output_extension will be used in the \"{{output_extension}}\"\n"
+    "  This value should not include a leading dot. If undefined, the default\n"
+    "  specified on the tool will be used. If set to the empty string, no\n"
+    "  output extension will be used.\n"
+    "\n"
+    "  The output_extension will be used to set the \"{{output_extension}}\"\n"
     "  expansion which the linker tool will generally use to specify the\n"
     "  output file name. See \"gn help tool\".\n"
     "\n"
     "Example\n"
     "\n"
     "  shared_library(\"freetype\") {\n"
     "    if (is_linux) {\n"
     "      # Call the output \"libfreetype.so.6\"\n"
     "      output_extension = \"so.6\"\n"
     "    }\n"
@@ skipping 30 matching lines @@
     "  to produce the file you want.\n"
     "\n"
     "  This variable is valid for all binary output target types.\n"
     "\n"
     "Example\n"
     "\n"
     "  static_library(\"doom_melon\") {\n"
     "    output_name = \"fluffy_bunny\"\n"
     "  }\n";
 
+const char kOutputPrefixOverride[] = "output_prefix_override";
+const char kOutputPrefixOverride_HelpShort[] =
+    "output_prefix_override: [boolean] Don't use prefix for output name.";
+const char kOutputPrefixOverride_Help[] =
+    "output_prefix_override: Don't use prefix for output name.\n"
+    "\n"
+    "  A boolean that overrides the output prefix for a target. Defaults to\n"
+    "  false.\n"
+    "\n"
+    "  Some systems use prefixes for the names of the final target output\n"
+    "  file. The normal example is \"libfoo.so\" on Linux for a target\n"
+    "  named \"foo\".\n"
+    "\n"
+    "  The output prefix for a given target type is specified on the linker\n"
+    "  tool (see \"gn help tool\"). Sometimes this prefix is undesired.\n"
+    "\n"
+    "  See also \"gn help output_extension\".\n"
+    "\n"
+    "Example\n"
+    "\n"
+    "  shared_library(\"doom_melon\") {\n"
+    "    # Normally this will produce \"libdoom_melon.so\" on Linux, setting\n"
+    "    # Setting this flag will produce \"doom_melon.so\".\n"
+    "    output_prefix_override = true\n"
+    "    ...\n"
+    "  }\n";
+
 const char kOutputs[] = "outputs";
 const char kOutputs_HelpShort[] =
     "outputs: [file list] Output files for actions and copy targets.";
 const char kOutputs_Help[] =
     "outputs: Output files for actions and copy targets.\n"
     "\n"
     "  Outputs is valid for \"copy\", \"action\", and \"action_foreach\"\n"
     "  target types and indicates the resulting files. Outputs must always\n"
     "  refer to files in the build directory.\n"
     "\n"
@@ skipping 444 matching lines @@
     INSERT_VARIABLE(Defines)
     INSERT_VARIABLE(Depfile)
     INSERT_VARIABLE(Deps)
     INSERT_VARIABLE(IncludeDirs)
     INSERT_VARIABLE(Inputs)
     INSERT_VARIABLE(Ldflags)
     INSERT_VARIABLE(Libs)
     INSERT_VARIABLE(LibDirs)
     INSERT_VARIABLE(OutputExtension)
     INSERT_VARIABLE(OutputName)
+    INSERT_VARIABLE(OutputPrefixOverride)
     INSERT_VARIABLE(Outputs)
     INSERT_VARIABLE(PrecompiledHeader)
     INSERT_VARIABLE(PrecompiledSource)
     INSERT_VARIABLE(Public)
     INSERT_VARIABLE(PublicConfigs)
     INSERT_VARIABLE(PublicDeps)
     INSERT_VARIABLE(ResponseFileContents)
     INSERT_VARIABLE(Script)
     INSERT_VARIABLE(Sources)
     INSERT_VARIABLE(Testonly)
     INSERT_VARIABLE(Visibility)
     INSERT_VARIABLE(WriteRuntimeDeps)
   }
   return info_map;
 }
 
 #undef INSERT_VARIABLE
 
 }  // namespace variables