🚙 GN: Add write_runtime_deps variable

tools/gn/variables.cc

Index: tools/gn/variables.cc
diff --git a/tools/gn/variables.cc b/tools/gn/variables.cc
index 81bb7e3ee535c495ed80f318b5591eb6a3ea250b..b97e3c634ca032f239e1480b8e7c266a0c51577c 100644
--- a/tools/gn/variables.cc
+++ b/tools/gn/variables.cc
@@ -1516,6 +1516,21 @@ const char kVisibility_Help[] =
     "  any targets in \"//bar/\" and any subdirectory thereof.\n"
     "    visibility = [ \"./*\", \"//bar/*\" ]\n";
 
+const char kWriteRuntimeDeps[] = "write_runtime_deps";
+const char kWriteRuntimeDeps_HelpShort[] =
+    "write_runtime_deps: Writes the target's runtime_deps to the given path.";
+const char kWriteRuntimeDeps_Help[] =
+    "write_runtime_deps: Writes the target's runtime_deps to the given path.\n"
+    "\n"
+    "  Does not synchronously write the file, but rather schedules it\n"
+    "  to be written at the end of generation.\n"
+    "\n"
+    "  If the file exists and the contents are identical to that being\n"
+    "  written, the file will not be updated. This will prevent unnecessary\n"
+    "  rebuilds of targets that depend on this file.\n"
+    "\n"
+    "  Path must be within the output directory.\n";

[brettw, 2016/03/28 23:06:35]

Can you add here:

See "gn help runtime_deps" for how the runtime dependencies are computed. 

The format of this file will list one file per line with no escaping. The files
will be relative to the root_build_dir. The first line of the file will be the
main output file of the target itself. The file contents will be the same as
requesting the runtime deps be written on the command line (see "gn help
--runtime-deps-list-file").

[agrieve, 2016/03/29 16:14:01]

Done.

+
 // -----------------------------------------------------------------------------
 
 VariableInfo::VariableInfo()
@@ -1596,6 +1611,7 @@ const VariableInfoMap& GetTargetVariables() {
     INSERT_VARIABLE(Sources)
     INSERT_VARIABLE(Testonly)
     INSERT_VARIABLE(Visibility)
+    INSERT_VARIABLE(WriteRuntimeDeps)
   }
   return info_map;
 }