From: Shenghou Ma <minux.ma@gmail.com>
Date: Tue, 14 Feb 2012 16:24:41 +0000 (-0500)
Subject: cmd/vet: give warning for construct 'Println(os.Stderr, ...)'
X-Git-Tag: weekly.2012-02-14~28
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=60e4d5668e80457023a3432752b2889fb73b89bf;p=gostls13.git

cmd/vet: give warning for construct 'Println(os.Stderr, ...)'
        also fixes this bug in net/http/httptest.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5654083
---

diff --git a/src/cmd/vet/print.go b/src/cmd/vet/print.go
index fe94137a7e..e0717f8e8e 100644
--- a/src/cmd/vet/print.go
+++ b/src/cmd/vet/print.go
@@ -207,7 +207,18 @@ func (f *File) checkPrintfVerb(call *ast.CallExpr, verb rune, flags []byte) {
 // call.Args[skip] is the first argument to be printed.
 func (f *File) checkPrint(call *ast.CallExpr, name string, skip int) {
 	isLn := strings.HasSuffix(name, "ln")
+	isF := strings.HasPrefix(name, "F")
 	args := call.Args
+	// check for Println(os.Stderr, ...)
+	if skip == 0 && !isF && len(args) > 0 {
+		if sel, ok := args[0].(*ast.SelectorExpr); ok {
+			if x, ok := sel.X.(*ast.Ident); ok {
+				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
+					f.Warnf(call.Pos(), "first argument to %s is %s.%s", name, x.Name, sel.Sel.Name)
+				}
+			}
+		}
+	}
 	if len(args) <= skip {
 		if *verbose && !isLn {
 			f.Badf(call.Pos(), "no args in %s call", name)
diff --git a/src/pkg/net/http/httptest/server.go b/src/pkg/net/http/httptest/server.go
index ace1bf3828..8d911f7575 100644
--- a/src/pkg/net/http/httptest/server.go
+++ b/src/pkg/net/http/httptest/server.go
@@ -95,7 +95,7 @@ func (s *Server) Start() {
 	s.URL = "http://" + s.Listener.Addr().String()
 	go s.Config.Serve(s.Listener)
 	if *serve != "" {
-		fmt.Println(os.Stderr, "httptest: serving on", s.URL)
+		fmt.Fprintln(os.Stderr, "httptest: serving on", s.URL)
 		select {}
 	}
 }