wire: improve error message for provider set conflicts (google/go-cloud#500)

internal/wire/testdata/MultipleBindings/foo/foo.go

@@ -0,0 +1,45 @@
+// 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 (
+	"io"
+	"strings"
+
+	"github.com/google/go-cloud/wire"
+)
+
+type context struct{}
+
+func main() {}
+
+type Foo string
+type Bar io.Reader
+
+var Set = wire.NewSet(provideFoo)
+var SuperSet = wire.NewSet(Set)
+var SetWithDuplicateBindings = wire.NewSet(Set, SuperSet)
+
+func provideFoo() Foo {
+	return Foo("foo")
+}
+
+func provideFooAgain() Foo {
+	return Foo("foo foo")
+}
+
+func provideBar() Bar {
+	return io.Reader(strings.NewReader("hello"))
+}

internal/wire/testdata/MultipleBindings/foo/wire.go

@@ -0,0 +1,53 @@
+// 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 (
+	"strings"
+
+	"github.com/google/go-cloud/wire"
+)
+
+func inject() Foo {
+	// fail: provideFoo and provideFooAgain both provide Foo.
+	panic(wire.Build(provideFoo, provideFooAgain))
+}
+
+func injectFromSet() Foo {
+	// fail: provideFoo is also provided by Set.
+	panic(wire.Build(provideFoo, Set))
+}
+
+func injectFromNestedSet() Foo {
+	// fail: provideFoo is also provided by SuperSet, via Set.
+	panic(wire.Build(provideFoo, SuperSet))
+}
+
+func injectFromSetWithDuplicateBindings() Foo {
+	// fail: DuplicateBindingsSet has two providers for Foo.
+	panic(wire.Build(SetWithDuplicateBindings))
+}
+
+func injectDuplicateValues() Foo {
+	// fail: provideFoo and wire.Value both provide Foo.
+	panic(wire.Build(provideFoo, wire.Value(Foo("foo"))))
+}
+
+func injectDuplicateInterface() Bar {
+	// fail: provideBar and wire.Bind both provide Bar.
+	panic(wire.Build(provideBar, wire.Bind(new(Bar), strings.NewReader("hello"))))
+}

internal/wire/testdata/MultipleBindings/pkg

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

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

@@ -0,0 +1,6 @@
+/wire_gopath/src/example.com/foo/wire.go:27:8: wire.Build has multiple bindings for example.com/foo.Foo (current binding: provider "provideFooAgain" (/wire_gopath/src/example.com/foo/foo.go:39:6); previous binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6)
+/wire_gopath/src/example.com/foo/wire.go:32:8: wire.Build has multiple bindings for example.com/foo.Foo (current binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6); previous binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6) <- provider set "Set" (/wire_gopath/src/example.com/foo/foo.go:31:11)
+/wire_gopath/src/example.com/foo/wire.go:37:8: wire.Build has multiple bindings for example.com/foo.Foo (current binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6); previous binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6) <- provider set "Set" (/wire_gopath/src/example.com/foo/foo.go:31:11) <- provider set "SuperSet" (/wire_gopath/src/example.com/foo/foo.go:32:16)
+/wire_gopath/src/example.com/foo/foo.go:33:32: SetWithDuplicateBindings has multiple bindings for example.com/foo.Foo (current binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6) <- provider set "Set" (/wire_gopath/src/example.com/foo/foo.go:31:11) <- provider set "SuperSet" (/wire_gopath/src/example.com/foo/foo.go:32:16); previous binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6) <- provider set "Set" (/wire_gopath/src/example.com/foo/foo.go:31:11)
+/wire_gopath/src/example.com/foo/wire.go:47:8: wire.Build has multiple bindings for example.com/foo.Foo (current binding: wire.Value (/wire_gopath/src/example.com/foo/wire.go:47:42); previous binding: provider "provideFoo" (/wire_gopath/src/example.com/foo/foo.go:35:6)
+/wire_gopath/src/example.com/foo/wire.go:52:8: wire.Build has multiple bindings for example.com/foo.Bar (current binding: wire.Bind (/wire_gopath/src/example.com/foo/wire.go:52:31); previous binding: provider "provideBar" (/wire_gopath/src/example.com/foo/foo.go:43:6)