add support for injecting build stamps with link options

examples/stamped_bin/BUILD

@@ -0,0 +1,19 @@
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+load("//go:def.bzl", "go_binary", "go_library")
+
+go_binary(
+    name = "stamped_bin",
+    srcs = ["main.go"],
+    linkstamp = "github.com/bazelbuild/rules_go/examples/stamped_bin/stamp",
+    deps = [
+        ":stamp",
+    ],
+)
+
+go_library(
+    name = "stamp",
+    srcs = ["stamp.go"],
+)

examples/stamped_bin/main.go

@@ -0,0 +1,30 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/bazelbuild/rules_go/examples/stamped_bin/stamp"
+)
+
+func main() {
+	fmt.Println(stamp.BUILD_TIMESTAMP)
+	if stamp.BUILD_TIMESTAMP == "fail" {
+		os.Exit(1)
+	}
+}

examples/stamped_bin/stamp.go

@@ -0,0 +1,18 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package stamp
+
+var BUILD_TIMESTAMP = "fail"

go/def.bzl

@@ -367,6 +367,7 @@ def emit_go_link_action(ctx, importmap, transitive_libs, cgo_deps, lib,
       ('../' * out_depth) + ctx.file.go_tool.path,
       "tool", "link", "-L", ".",
       "-o", _go_importpath(ctx),
+      '"${STAMP_XDEFS[@]}"',
   ]
 
   if x_defs:
@@ -389,9 +390,25 @@ def emit_go_link_action(ctx, importmap, transitive_libs, cgo_deps, lib,
   # Avoided -s on OSX but but it requires dsymutil to be on $PATH.
   # TODO(yugui) Remove this workaround once rules_go stops supporting XCode 7.2
   # or earlier.
-  cmds += ["export PATH=$PATH:/usr/bin"]
   cmds += [
+    "export PATH=$PATH:/usr/bin",
     "export GOROOT=$(pwd)/" + ctx.file.go_tool.dirname + "/..",
+    "declare -a STAMP_XDEFS",
+  ]
+
+  stamp_input = []
+  if ctx.attr.linkstamp:
+    stamp_input = [ctx.info_file, ctx.version_file]
+    for f in stamp_input:
+      cmds += [
+          "while read -r stamp || [[ -n $stamp ]]; do",
+          # reads workspace status file, converting "KEY value" lines to "-X KEY=$linkstamp.value" arguments to the go linker.
+          "if echo $stamp | grep -qe '^.*[[:space:]].*$'; then",
+          "STAMP_XDEFS+=(-X \"$(echo \"%s.${stamp}\" | tr ' ' '=')\");" % ctx.attr.linkstamp,
+          "fi",
+          "done < " + f.path,
+      ]
+  cmds += [
     "cd " + out_dir,
     ' '.join(link_cmd),
     "mv -f " + _go_importpath(ctx) + " " + ("../" * out_depth) + executable.path,
@@ -401,7 +418,7 @@ def emit_go_link_action(ctx, importmap, transitive_libs, cgo_deps, lib,
 
   ctx.action(
       inputs = (list(transitive_libs) + [lib] + list(cgo_deps) +
-                ctx.files.toolchain + ctx.files._crosstool),
+                ctx.files.toolchain + ctx.files._crosstool) + stamp_input,
       outputs = [executable],
       executable = f,
       mnemonic = "GoLink",
@@ -558,7 +575,7 @@ go_library = rule(
 go_binary = rule(
     go_binary_impl,
     attrs = go_library_attrs + _crosstool_attrs + {
-        "stamp": attr.bool(default = False),
+        "linkstamp": attr.string(default = ""),
         "x_defs": attr.string_dict(),
     },
     executable = True,
@@ -576,6 +593,7 @@ go_test = rule(
             ),
             cfg = "host",
         ),
+        "linkstamp": attr.string(default = ""),
         "x_defs": attr.string_dict(),
     },
     executable = True,