From 925a11ad0d3a3591ccd4c1f99e085718267fe6ad Mon Sep 17 00:00:00 2001
From: Robert van Gent <rvangent@google.com>
Date: Fri, 16 Nov 2018 13:27:30 -0800
Subject: [PATCH] wire: add a test for using a function argument as a provider
 (google/go-cloud#724)

---
 internal/wire/parse.go                        |  2 +-
 .../wire/testdata/FuncArgProvider/foo/foo.go  | 36 +++++++++++++++++++
 .../wire/testdata/FuncArgProvider/foo/wire.go | 26 ++++++++++++++
 internal/wire/testdata/FuncArgProvider/pkg    |  1 +
 .../FuncArgProvider/want/wire_errs.txt        |  1 +
 5 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 internal/wire/testdata/FuncArgProvider/foo/foo.go
 create mode 100644 internal/wire/testdata/FuncArgProvider/foo/wire.go
 create mode 100644 internal/wire/testdata/FuncArgProvider/pkg
 create mode 100644 internal/wire/testdata/FuncArgProvider/want/wire_errs.txt

diff --git a/internal/wire/parse.go b/internal/wire/parse.go
index 558551e..8b57e28 100644
--- a/internal/wire/parse.go
+++ b/internal/wire/parse.go
@@ -455,7 +455,7 @@ func (oc *objectCache) get(obj types.Object) (val interface{}, errs []error) {
 	switch obj := obj.(type) {
 	case *types.Var:
 		spec := oc.varDecl(obj)
-		if len(spec.Values) == 0 {
+		if spec == nil || len(spec.Values) == 0 {
 			return nil, []error{fmt.Errorf("%v is not a provider or a provider set", obj)}
 		}
 		var i int
diff --git a/internal/wire/testdata/FuncArgProvider/foo/foo.go b/internal/wire/testdata/FuncArgProvider/foo/foo.go
new file mode 100644
index 0000000..e794e4c
--- /dev/null
+++ b/internal/wire/testdata/FuncArgProvider/foo/foo.go
@@ -0,0 +1,36 @@
+// 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() {
+	bar := injectBar(func() *Foo { return &Foo{42} })
+	fmt.Println(bar.Name)
+}
+
+type Foo struct {
+	Val int
+}
+
+type Bar struct {
+	Name string
+}
+
+func NewBar(f *Foo) *Bar {
+	return &Bar{Name: fmt.Sprintf("foo value %d", f.Val)}
+}
diff --git a/internal/wire/testdata/FuncArgProvider/foo/wire.go b/internal/wire/testdata/FuncArgProvider/foo/wire.go
new file mode 100644
index 0000000..b970f83
--- /dev/null
+++ b/internal/wire/testdata/FuncArgProvider/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 injectBar(fn func() *Foo) *Bar {
+	// fails because it doesn't identify fn as a Provider; see #723.
+	panic(wire.Build(fn, NewBar))
+}
diff --git a/internal/wire/testdata/FuncArgProvider/pkg b/internal/wire/testdata/FuncArgProvider/pkg
new file mode 100644
index 0000000..f7a5c8c
--- /dev/null
+++ b/internal/wire/testdata/FuncArgProvider/pkg
@@ -0,0 +1 @@
+example.com/foo
diff --git a/internal/wire/testdata/FuncArgProvider/want/wire_errs.txt b/internal/wire/testdata/FuncArgProvider/want/wire_errs.txt
new file mode 100644
index 0000000..7155e14
--- /dev/null
+++ b/internal/wire/testdata/FuncArgProvider/want/wire_errs.txt
@@ -0,0 +1 @@
+example.com/foo/wire.go:x:y: var fn func() *example.com/foo.Foo is not a provider or a provider set
\ No newline at end of file