add tools.go to codify our tools in go.mod (#132)

go.mod

@@ -2,6 +2,10 @@ module google.golang.org/genproto
 
 require (
 	github.com/golang/protobuf v1.2.0
+	golang.org/x/exp v0.0.0-20190121172915-509febef88a4
+	golang.org/x/lint v0.0.0-20180702182130-06c8688daad7
 	golang.org/x/net v0.0.0-20181106065722-10aee1819953
+	golang.org/x/tools v0.0.0-20180828015842-6cd1fcedba52
 	google.golang.org/grpc v1.16.0
+	honnef.co/go/tools v0.0.0-20180728063816-88497007e858
 )

go.sum

@@ -6,7 +6,11 @@ github.com/golang/lint v0.0.0-20180702182130-06c8688daad7/go.mod h1:tluoj9z5200j
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/kisielk/gotool v1.0.0 h1:AV2c/EiW3KqPNT9ZKl07ehoAGi4C5/01Cfbblndcapg=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+golang.org/x/exp v0.0.0-20190121172915-509febef88a4 h1:c2HOrn5iMezYjSlGPncknSEr/8x5LELb/ilJbXi9DEA=
+golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
+golang.org/x/lint v0.0.0-20180702182130-06c8688daad7 h1:00BeQWmeaGazuOrq8Q5K5d3/cHaGuFrZzpaHBXfrsUA=
 golang.org/x/lint v0.0.0-20180702182130-06c8688daad7/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181106065722-10aee1819953 h1:LuZIitY8waaxUfNIdtajyE/YzA/zyf0YxXG27VpLrkg=
@@ -18,9 +22,11 @@ golang.org/x/sys v0.0.0-20180830151530-49385e6e1522 h1:Ve1ORMCxvRmSXBwJK+t3Oy+V2
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20180828015842-6cd1fcedba52 h1:JG/0uqcGdTNgq7FdU+61l5Pdmb8putNZlXb65bJBROs=
 golang.org/x/tools v0.0.0-20180828015842-6cd1fcedba52/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/grpc v1.16.0 h1:dz5IJGuC2BB7qXR5AyHNwAUBhZscK2xVez7mznh72sY=
 google.golang.org/grpc v1.16.0/go.mod h1:0JHn/cJsOMiMfNA9+DeHDlAU7KAAB5GDlYFpa9MZMio=
+honnef.co/go/tools v0.0.0-20180728063816-88497007e858 h1:wN+eVZ7U+gqdqkec6C6VXR1OFf9a5Ul9ETzeYsYv20g=
 honnef.co/go/tools v0.0.0-20180728063816-88497007e858/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

tools.go

+// +build tools
+
+// Copyright 2019 Google LLC
+//
+// 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.
+
+// This package exists to cause `go mod` and `go get` to believe these tools
+// are dependencies, even though they are not runtime dependencies of any
+// package (these are tools used by our CI builds). This means they will appear
+// in our `go.mod` file, but will not be a part of the build. Also, since the
+// build target is something non-existent, these should not be included in any
+// binaries.
+
+package genproto
+
+import (
+	_ "github.com/golang/protobuf/protoc-gen-go"
+	_ "golang.org/x/exp/cmd/apidiff"
+	_ "golang.org/x/lint/golint"
+	_ "golang.org/x/tools/cmd/goimports"
+	_ "honnef.co/go/tools/cmd/staticcheck"
+)