--- /dev/null
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fillreturns
+
+import (
+ "errors"
+ "go/ast"
+ ast2 "go/ast"
+ "io"
+ "net/http"
+ . "net/http"
+ "net/url"
+ "strconv"
+)
+
+type T struct{}
+type T1 = T
+type I interface{}
+type I1 = I
+type z func(string, http.Handler) error
+
+func x() error {
+ return errors.New("foo")
+}
+
+func b() (string, int, error) {
+ return "", errors.New("foo") // want "wrong number of return values \\(want 3, got 2\\)"
+}
+
+func c() (string, int, error) {
+ return 7, errors.New("foo") // want "wrong number of return values \\(want 3, got 2\\)"
+}
+
+func d() (string, int, error) {
+ return "", 7 // want "wrong number of return values \\(want 3, got 2\\)"
+}
+
+func e() (T, error, *bool) {
+ return (z(http.ListenAndServe))("", nil) // want "wrong number of return values \\(want 3, got 1\\)"
+}
+
+func preserveLeft() (int, int, error) {
+ return 1, errors.New("foo") // want "wrong number of return values \\(want 3, got 2\\)"
+}
+
+func matchValues() (int, error, string) {
+ return errors.New("foo"), 3 // want "wrong number of return values \\(want 3, got 2\\)"
+}
+
+func preventDataOverwrite() (int, string) {
+ return errors.New("foo") // want "wrong number of return values \\(want 2, got 1\\)"
+}
+
+func closure() (string, error) {
+ _ = func() (int, error) {
+ return // want "wrong number of return values \\(want 2, got 0\\)"
+ }
+ return // want "wrong number of return values \\(want 2, got 0\\)"
+}
+
+func basic() (uint8, uint16, uint32, uint64, int8, int16, int32, int64, float32, float64, complex64, complex128, byte, rune, uint, int, uintptr, string, bool, error) {
+ return // want "wrong number of return values \\(want 20, got 0\\)"
+}
+
+func complex() (*int, []int, [2]int, map[int]int) {
+ return // want "wrong number of return values \\(want 4, got 0\\)"
+}
+
+func structsAndInterfaces() (T, url.URL, T1, I, I1, io.Reader, Client, ast2.Stmt) {
+ return // want "wrong number of return values \\(want 8, got 0\\)"
+}
+
+func m() (int, error) {
+ if 1 == 2 {
+ return // want "wrong number of return values \\(want 2, got 0\\)"
+ } else if 1 == 3 {
+ return errors.New("foo") // want "wrong number of return values \\(want 2, got 1\\)"
+ } else {
+ return 1 // want "wrong number of return values \\(want 2, got 1\\)"
+ }
+ return // want "wrong number of return values \\(want 2, got 0\\)"
+}
+
+func convertibleTypes() (ast2.Expr, int) {
+ return &ast2.ArrayType{} // want "wrong number of return values \\(want 2, got 1\\)"
+}
+
+func assignableTypes() (map[string]int, int) {
+ type X map[string]int
+ var x X
+ return x // want "wrong number of return values \\(want 2, got 1\\)"
+}
+
+func interfaceAndError() (I, int) {
+ return errors.New("foo") // want "wrong number of return values \\(want 2, got 1\\)"
+}
+
+func funcOneReturn() (string, error) {
+ return strconv.Itoa(1) // want "wrong number of return values \\(want 2, got 1\\)"
+}
+
+func funcMultipleReturn() (int, error, string) {
+ return strconv.Atoi("1")
+}
+
+func localFuncMultipleReturn() (string, int, error, string) {
+ return b()
+}
+
+func multipleUnused() (int, string, string, string) {
+ return 3, 4, 5 // want "wrong number of return values \\(want 4, got 3\\)"
+}
+
+func gotTooMany() int {
+ if true {
+ return 0, "" // want "wrong number of return values \\(want 1, got 2\\)"
+ } else {
+ return 1, 0, nil // want "wrong number of return values \\(want 1, got 3\\)"
+ }
+ return 0, 5, false // want "wrong number of return values \\(want 1, got 3\\)"
+}
+
+func fillVars() (int, string, ast.Node, bool, error) {
+ eint := 0
+ s := "a"
+ var t bool
+ if true {
+ err := errors.New("fail")
+ return // want "wrong number of return values \\(want 5, got 0\\)"
+ }
+ n := ast.NewIdent("ident")
+ int := 3
+ var b bool
+ return "" // want "wrong number of return values \\(want 5, got 1\\)"
+}