all: simplify and clarify some expressions (google/go-cloud#260)

internal/wire/parse.go

@@ -716,19 +716,17 @@ func processValue(fset *token.FileSet, info *types.Info, call *ast.CallExpr) (*V
 	}
 	ok := true
 	ast.Inspect(call.Args[0], func(node ast.Node) bool {
-		switch node.(type) {
+		switch expr := node.(type) {
 		case nil, *ast.ArrayType, *ast.BasicLit, *ast.BinaryExpr, *ast.ChanType, *ast.CompositeLit, *ast.FuncType, *ast.Ident, *ast.IndexExpr, *ast.InterfaceType, *ast.KeyValueExpr, *ast.MapType, *ast.ParenExpr, *ast.SelectorExpr, *ast.SliceExpr, *ast.StarExpr, *ast.StructType, *ast.TypeAssertExpr:
 			// Good!
 		case *ast.UnaryExpr:
-			expr := node.(*ast.UnaryExpr)
 			if expr.Op == token.ARROW {
 				ok = false
 				return false
 			}
 		case *ast.CallExpr:
 			// Only acceptable if it's a type conversion.
-			call := node.(*ast.CallExpr)
-			if _, isFunc := info.TypeOf(call.Fun).(*types.Signature); isFunc {
+			if _, isFunc := info.TypeOf(expr.Fun).(*types.Signature); isFunc {
 				ok = false
 				return false
 			}

internal/wire/wire.go

@@ -366,7 +366,7 @@ func (g *gen) rewritePkgRefs(info *types.Info, node ast.Node) ast.Node {
 			if len(scopeStack) > 0 {
 				// Avoid picking a name that conflicts with other names in the
 				// current scope.
-				_, obj := scopeStack[len(scopeStack)-1].LookupParent(n, 0)
+				_, obj := scopeStack[len(scopeStack)-1].LookupParent(n, token.NoPos)
 				if obj != nil {
 					return true
 				}
@@ -436,7 +436,7 @@ func (g *gen) nameInFileScope(name string) bool {
 			return true
 		}
 	}
-	_, obj := g.prog.Package(g.currPackage).Pkg.Scope().LookupParent(name, 0)
+	_, obj := g.prog.Package(g.currPackage).Pkg.Scope().LookupParent(name, token.NoPos)
 	return obj != nil
 }
 
@@ -481,13 +481,14 @@ func injectPass(name string, params *types.Tuple, injectSig outputSignature, cal
 		ig.p("%s %s", ig.paramNames[i], types.TypeString(pi.Type(), ig.g.qualifyPkg))
 	}
 	outTypeString := types.TypeString(injectSig.out, ig.g.qualifyPkg)
-	if injectSig.cleanup && injectSig.err {
+	switch {
+	case injectSig.cleanup && injectSig.err:
 		ig.p(") (%s, func(), error) {\n", outTypeString)
-	} else if injectSig.cleanup {
+	case injectSig.cleanup:
 		ig.p(") (%s, func()) {\n", outTypeString)
-	} else if injectSig.err {
+	case injectSig.err:
 		ig.p(") (%s, error) {\n", outTypeString)
-	} else {
+	default:
 		ig.p(") %s {\n", outTypeString)
 	}
 	for i := range calls {

internal/wire/wire_test.go

@@ -513,7 +513,7 @@ type dirInfo struct {
 
 func (d dirInfo) Name() string       { return d.name }
 func (d dirInfo) Size() int64        { return 0 }
-func (d dirInfo) Mode() os.FileMode  { return os.ModeDir | 0777 }
+func (d dirInfo) Mode() os.FileMode  { return os.ModeDir | os.ModePerm }
 func (d dirInfo) ModTime() time.Time { return time.Unix(0, 0) }
 func (d dirInfo) IsDir() bool        { return true }
 func (d dirInfo) Sys() interface{}   { return nil }