wire: avoid making variable names that are Go reserved keywords (google/go-cloud#486)

internal/wire/testdata/ReservedKeywords/foo/foo.go

@@ -0,0 +1,35 @@
+// Copyright 2018 The Go Cloud Authors
+//
+// 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
+//
+//     https://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"
+)
+
+func main() {
+	i := injectInterface()
+	fmt.Println(i)
+}
+
+type Interface int
+type Select int
+
+func provideInterface(s Select) Interface {
+	return Interface(int(s) + 1)
+}
+
+func provideSelect() Select {
+	return Select(41)
+}

internal/wire/testdata/ReservedKeywords/foo/wire.go

@@ -0,0 +1,32 @@
+// Copyright 2018 The Go Cloud Authors
+//
+// 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
+//
+//     https://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.
+
+//+build wireinject
+
+package main
+
+import (
+	"github.com/google/go-cloud/wire"
+)
+
+// Wire tries to disambiguate the variable "select" by prepending
+// the package name; this package-scoped variable conflicts with that
+// and forces a different name.
+var mainSelect = 0
+
+func injectInterface() Interface {
+	// interface and select are Go reserved words, so
+	// Wire should avoid using them as variable names.
+	panic(wire.Build(provideInterface, provideSelect))
+}

internal/wire/testdata/ReservedKeywords/pkg

@@ -0,0 +1 @@
+example.com/foo

internal/wire/testdata/ReservedKeywords/want/program_out.txt

@@ -0,0 +1 @@
+42

internal/wire/testdata/ReservedKeywords/want/wire_gen.go

@@ -0,0 +1,18 @@
+// Code generated by Wire. DO NOT EDIT.
+
+//go:generate wire
+//+build !wireinject
+
+package main
+
+// Injectors from wire.go:
+
+func injectInterface() Interface {
+	select2 := provideSelect()
+	mainInterface := provideInterface(select2)
+	return mainInterface
+}
+
+// wire.go:
+
+var mainSelect = 0

internal/wire/wire.go

@@ -709,7 +709,7 @@ func typeVariableName(t types.Type, defaultName string, transform func(string) s
 
 	// See if there's an unambiguous name; if so, use it.
 	for _, name := range names {
-		if !collides(name) {
+		if !reservedKeyword[name] && !collides(name) {
 			return name
 		}
 	}
@@ -767,9 +767,40 @@ func export(name string) string {
 	return sbuf.String()
 }
 
+// reservedKeyword is a set of Go's reserved keywords:
+// https://golang.org/ref/spec#Keywords
+var reservedKeyword = map[string]bool{
+	"break":       true,
+	"case":        true,
+	"chan":        true,
+	"const":       true,
+	"continue":    true,
+	"default":     true,
+	"defer":       true,
+	"else":        true,
+	"fallthrough": true,
+	"for":         true,
+	"func":        true,
+	"go":          true,
+	"goto":        true,
+	"if":          true,
+	"import":      true,
+	"interface":   true,
+	"map":         true,
+	"package":     true,
+	"range":       true,
+	"return":      true,
+	"select":      true,
+	"struct":      true,
+	"switch":      true,
+	"type":        true,
+	"var":         true,
+}
+
 // disambiguate picks a unique name, preferring name if it is already unique.
+// It also disambiguates against Go's reserved keywords.
 func disambiguate(name string, collides func(string) bool) string {
-	if !collides(name) {
+	if !reservedKeyword[name] && !collides(name) {
 		return name
 	}
 	buf := []byte(name)
@@ -780,7 +811,7 @@ func disambiguate(name string, collides func(string) bool) string {
 	for n := 2; ; n++ {
 		buf = strconv.AppendInt(buf[:base], int64(n), 10)
 		sbuf := string(buf)
-		if !collides(sbuf) {
+		if !reservedKeyword[sbuf] && !collides(sbuf) {
 			return sbuf
 		}
 	}

internal/wire/wire_test.go

@@ -303,6 +303,8 @@ func TestDisambiguate(t *testing.T) {
 		{"foo1", "foo1_2", map[string]bool{"foo": true, "foo1": true, "foo2": true}},
 		{"foo\u0661", "foo\u0661", map[string]bool{"foo": true, "foo1": true, "foo2": true}},
 		{"foo\u0661", "foo\u06612", map[string]bool{"foo": true, "foo1": true, "foo2": true, "foo\u0661": true}},
+		{"select", "select2", nil},
+		{"var", "var2", nil},
 	}
 	for _, test := range tests {
 		t.Run(fmt.Sprintf("disambiguate(%q, %v)", test.name, test.collides), func(t *testing.T) {