gofix: httpserver - rewrite rw.SetHeader to rw.Header.Set

R=rsc
CC=golang-dev
https://golang.org/cl/4271048

src/cmd/gofix/httpserver.go

@@ -51,7 +51,7 @@ func httpserver(f *ast.File) bool {
 
 			// Look for w.UsingTLS() and w.Remoteaddr().
 			call, ok := n.(*ast.CallExpr)
-			if !ok || len(call.Args) != 0 {
+			if !ok || (len(call.Args) != 0 && len(call.Args) != 2) {
 				return
 			}
 			sel, ok := call.Fun.(*ast.SelectorExpr)
@@ -102,6 +102,21 @@ func httpserver(f *ast.File) bool {
 					Sel: ast.NewIdent("RemoteAddr"),
 				}
 				fixed = true
+			case "SetHeader":
+				// replace w.SetHeader with w.Header().Set
+				// or w.Header().Del if second argument is ""
+				sel.X = &ast.CallExpr{
+					Fun: &ast.SelectorExpr{
+						X:   ast.NewIdent(w.String()),
+						Sel: ast.NewIdent("Header"),
+					},
+				}
+				sel.Sel = ast.NewIdent("Set")
+				if len(call.Args) == 2 && isEmptyString(call.Args[1]) {
+					sel.Sel = ast.NewIdent("Del")
+					call.Args = call.Args[:1]
+				}
+				fixed = true
 			}
 		})
 	}

src/cmd/gofix/httpserver_test.go

@@ -16,6 +16,8 @@ var httpserverTests = []testCase{
 import "http"
 
 func f(xyz http.ResponseWriter, abc *http.Request, b string) {
+	xyz.SetHeader("foo", "bar")
+	xyz.SetHeader("baz", "")
 	xyz.Hijack()
 	xyz.Flush()
 	go xyz.Hijack()
@@ -33,6 +35,8 @@ func f(xyz http.ResponseWriter, abc *http.Request, b string) {
 import "http"
 
 func f(xyz http.ResponseWriter, abc *http.Request, b string) {
+	xyz.Header().Set("foo", "bar")
+	xyz.Header().Del("baz")
 	xyz.(http.Hijacker).Hijack()
 	xyz.(http.Flusher).Flush()
 	go xyz.(http.Hijacker).Hijack()