GN: Add symlink rules for dump_syms, symupload

build/symlink.gni

+# Copyright 2015 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.
+
+# Creates a symlink.
+# Args:
+#   source: Path to link to.
+#   output: Where to create the symlink.
+template("symlink") {
+  action(target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "deps",
+                             "testonly",
+                             "visibility",
+                           ])
+    outputs = [
+      invoker.output,
+    ]
+    script = "//build/symlink.py"
+    args = [
+      "-f",
+      rebase_path(invoker.source, get_path_info(invoker.output, "dir")),
+      rebase_path(invoker.output, root_build_dir),
+    ]
+  }
+}
+
+# Creates a symlink from root_build_dir/target_name to |binary_label|, which
+# can be convenient when target_toolchain != host_toolchain.
+# Note that for executables, using a copy (as opposed to a symlink) does not
+# work when is_component_build=true, since dependent libraries are found via
+# relative location.

[brettw, 2015/12/10 18:20:03]

I think it would be worth adding here how you will want to put such targets
inside a condition like:
  if (current_toolchain == default_toolchain) {
otherwise there will be multiple rules (one for each toolchain the file is
executed in) that generates the symlink.

[agrieve, 2015/12/11 10:37:01]

Done.

+# Args:
+#   binary_label: Target that builds the file to symlink to. e.g.:
+#       ":foo($host_toolchain)".
+#   output: Where to create the symlink (default="$root_out_dir/$target_name")
+template("host_binary_symlink") {

[brettw, 2015/12/10 18:20:03]

Since callers how have to specify the toolchain in the binary label, this should
probably be called "binary_symlink" instead.

[agrieve, 2015/12/11 10:37:01]

Done.

+  symlink(target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "output",
+                             "testonly",
+                             "visibility",
+                           ])
+    deps = [
+      invoker.binary_label,
+    ]
+
+    _out_dir = get_label_info(invoker.binary_label, "root_out_dir")
+    source = "$_out_dir/" + get_label_info(invoker.binary_label, "name")
+
+    if (!defined(output)) {
+      output = "$root_out_dir/${invoker.target_name}"
+    }
+  }
+}