wire: wire.FieldsOf should not provide pointer to field type for non-pointer structs (#210)

internal/wire/testdata/FieldsOfStruct/foo/foo.go

@@ -26,5 +26,4 @@ func provideS() S {
 
 func main() {
 	fmt.Println(injectedMessage())
-	fmt.Println("pointer to " + *injectedMessagePtr())
 }

internal/wire/testdata/FieldsOfStruct/foo/wire.go

@@ -26,10 +26,3 @@ func injectedMessage() string {
 		wire.FieldsOf(new(S), "Foo"))
 	return ""
 }
-
-func injectedMessagePtr() *string {
-	wire.Build(
-		provideS,
-		wire.FieldsOf(new(S), "Foo"))
-	return nil
-}

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

@@ -1,2 +1 @@
 Hello, World!
-pointer to Hello, World!

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

@@ -12,9 +12,3 @@ func injectedMessage() string {
 	string2 := s.Foo
 	return string2
 }
-
-func injectedMessagePtr() *string {
-	s := provideS()
-	string2 := &s.Foo
-	return string2
-}

internal/wire/testdata/FieldsOfStructDoNotProvidePtrToField/foo/foo.go

@@ -0,0 +1,29 @@
+// Copyright 2019 The Wire 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"
+
+type S struct {
+	Foo string
+}
+
+func provideS() S {
+	return S{Foo: "Hello, World!"}
+}
+
+func main() {
+	fmt.Println("pointer to " + *injectedMessagePtr())
+}

internal/wire/testdata/FieldsOfStructDoNotProvidePtrToField/foo/wire.go

@@ -0,0 +1,32 @@
+// Copyright 2019 The Wire 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/wire"
+)
+
+func injectedMessagePtr() *string {
+	// This shouldn't work; FieldsOf provides a pointer to the
+	// field only when the struct type is a pointer to a struct.
+	// See FieldsOfStructPointer for a working example using
+	// a pointer to a struct.
+	wire.Build(
+		provideS,
+		wire.FieldsOf(new(S), "Foo"))
+	return nil
+}

internal/wire/testdata/FieldsOfStructDoNotProvidePtrToField/pkg

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

internal/wire/testdata/FieldsOfStructDoNotProvidePtrToField/want/wire_errs.txt

@@ -0,0 +1 @@
+example.com/foo/wire.go:x:y: inject injectedMessagePtr: no provider found for *string, output of injector

internal/wire/testdata/FieldsOfStructPointer/foo/foo.go

@@ -26,4 +26,5 @@ func provideS() *S {
 
 func main() {
 	fmt.Println(injectedMessage())
+	fmt.Println("pointer to " + *injectedMessagePtr())
 }

internal/wire/testdata/FieldsOfStructPointer/foo/wire.go

@@ -26,3 +26,10 @@ func injectedMessage() string {
 		wire.FieldsOf(new(*S), "Foo"))
 	return ""
 }
+
+func injectedMessagePtr() *string {
+	wire.Build(
+		provideS,
+		wire.FieldsOf(new(*S), "Foo"))
+	return nil
+}

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

@@ -1 +1,2 @@
 Hello, World!
+pointer to Hello, World!

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

@@ -12,3 +12,9 @@ func injectedMessage() string {
 	string2 := s.Foo
 	return string2
 }
+
+func injectedMessagePtr() *string {
+	s := provideS()
+	string2 := &s.Foo
+	return string2
+}