wire: allow wire.Value to use values with no parent (i.e., struct fields) (google/go-cloud#596)

README.md

@@ -327,9 +327,13 @@ The generated injector would look like this:
 
 ```go
 func injectFoo() Foo {
-    foo := Foo{X: 42}
+    foo := _wireFooValue
     return foo
 }
+
+var (
+    _wireFooValue = Foo{X: 42}
+)
 ```
 
 It's important to note that the expression will be copied to the injector's

internal/wire/testdata/UnexportedStruct/bar/bar.go

@@ -0,0 +1,21 @@
+// 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 bar
+
+var foo struct {
+	X int
+}
+
+

internal/wire/testdata/UnexportedStruct/foo/foo.go

@@ -0,0 +1,21 @@
+// 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() {
+	fmt.Printf("%v\n", injectedBar())
+}

internal/wire/testdata/UnexportedStruct/foo/wire.go

@@ -0,0 +1,28 @@
+// 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 (
+	"example.com/bar"
+	"github.com/google/go-cloud/wire"
+)
+
+func injectedBar() string {
+	// Fails because bar.foo is unexported.
+	wire.Build(bar.foo.X)
+	return ""
+}

internal/wire/testdata/UnexportedStruct/pkg

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

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

@@ -0,0 +1 @@
+/wire_gopath/src/example.com/foo/wire.go:x:y: foo not exported by package bar

internal/wire/testdata/UnexportedValue/foo/wire.go

@@ -22,6 +22,7 @@ import (
 )
 
 func injectedMessage() string {
+	// Fails because bar.Value references unexported bar.privateMsg.
 	wire.Build(bar.Value)
 	return ""
 }

internal/wire/testdata/ValueIsStruct/foo/foo.go

@@ -0,0 +1,28 @@
+// 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() {
+	f := injectFoo()
+	fmt.Printf("%d\n", f.X)
+}
+
+type Foo struct {
+	X int
+}

internal/wire/testdata/ValueIsStruct/foo/wire.go

@@ -0,0 +1,26 @@
+// 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"
+)
+
+func injectFoo() Foo {
+	wire.Build(wire.Value(Foo{X: 42}))
+	return Foo{}
+}

internal/wire/testdata/ValueIsStruct/pkg

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

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

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

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

@@ -0,0 +1,17 @@
+// Code generated by Wire. DO NOT EDIT.
+
+//go:generate wire
+//+build !wireinject
+
+package main
+
+// Injectors from wire.go:
+
+func injectFoo() Foo {
+	foo := _wireFooValue
+	return foo
+}
+
+var (
+	_wireFooValue = Foo{X: 42}
+)

internal/wire/wire.go

@@ -845,7 +845,7 @@ func accessibleFrom(info *types.Info, node ast.Node, wantPkg string) error {
 				unexportError = fmt.Errorf("uses unexported identifier %s", obj.Name())
 				return false
 			}
-			if obj.Parent() != pkg.Scope() {
+			if obj.Parent() != nil && obj.Parent() != pkg.Scope() {
 				unexportError = fmt.Errorf("%s is not declared in package scope", obj.Name())
 				return false
 			}