pkg: remove .String() from some print arguments

I found these by adding a check to govet, but the check
produces far too many false positives to be useful.
Even so, these few seem worth cleaning up.

R=golang-dev, bradfitz, iant
CC=golang-dev
https://golang.org/cl/5311067

src/pkg/crypto/bcrypt/bcrypt_test.go

@@ -86,7 +86,7 @@ func TestInvalidHashErrors(t *testing.T) {
 			t.Errorf("%s: Should have returned an error", name)
 		}
 		if err != nil && err != expected {
-			t.Errorf("%s gave err %v but should have given %v", name, err.String(), expected.String())
+			t.Errorf("%s gave err %v but should have given %v", name, err, expected)
 		}
 	}
 	for _, iht := range invalidTests {

src/pkg/exp/gui/x11/conn.go

@@ -87,7 +87,7 @@ func (c *conn) writeSocket() {
 			setU32LE(c.flushBuf0[16:20], uint32(y<<16))
 			if _, err := c.w.Write(c.flushBuf0[:24]); err != nil {
 				if err != os.EOF {
-					log.Println("x11:", err.String())
+					log.Println("x11:", err)
 				}
 				return
 			}
@@ -106,7 +106,7 @@ func (c *conn) writeSocket() {
 				x += nx
 				if _, err := c.w.Write(c.flushBuf1[:nx]); err != nil {
 					if err != os.EOF {
-						log.Println("x11:", err.String())
+						log.Println("x11:", err)
 					}
 					return
 				}
@@ -114,7 +114,7 @@ func (c *conn) writeSocket() {
 		}
 		if err := c.w.Flush(); err != nil {
 			if err != os.EOF {
-				log.Println("x11:", err.String())
+				log.Println("x11:", err)
 			}
 			return
 		}

src/pkg/expvar/expvar.go

@@ -102,7 +102,7 @@ func (v *Map) String() string {
 		if !first {
 			fmt.Fprintf(b, ", ")
 		}
-		fmt.Fprintf(b, "\"%s\": %v", key, val.String())
+		fmt.Fprintf(b, "\"%s\": %v", key, val)
 		first = false
 	}
 	fmt.Fprintf(b, "}")

src/pkg/go/ast/print.go

@@ -149,7 +149,7 @@ func (p *printer) print(x reflect.Value) {
 		p.print(x.Elem())
 
 	case reflect.Map:
-		p.printf("%s (len = %d) {\n", x.Type().String(), x.Len())
+		p.printf("%s (len = %d) {\n", x.Type(), x.Len())
 		p.indent++
 		for _, key := range x.MapKeys() {
 			p.print(key)
@@ -178,7 +178,7 @@ func (p *printer) print(x reflect.Value) {
 			p.printf("%#q", s)
 			return
 		}
-		p.printf("%s (len = %d) {\n", x.Type().String(), x.Len())
+		p.printf("%s (len = %d) {\n", x.Type(), x.Len())
 		p.indent++
 		for i, n := 0, x.Len(); i < n; i++ {
 			p.printf("%d: ", i)
@@ -189,7 +189,7 @@ func (p *printer) print(x reflect.Value) {
 		p.printf("}")
 
 	case reflect.Struct:
-		p.printf("%s {\n", x.Type().String())
+		p.printf("%s {\n", x.Type())
 		p.indent++
 		t := x.Type()
 		for i, n := 0, t.NumField(); i < n; i++ {

src/pkg/go/scanner/errors.go

@@ -92,7 +92,7 @@ func (p ErrorList) String() string {
 	case 1:
 		return p[0].String()
 	}
-	return fmt.Sprintf("%s (and %d more errors)", p[0].String(), len(p)-1)
+	return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
 }
 
 // These constants control the construction of the ErrorList

src/pkg/go/scanner/scanner_test.go

@@ -237,7 +237,7 @@ func TestScan(t *testing.T) {
 		}
 		checkPos(t, lit, pos, epos)
 		if tok != e.tok {
-			t.Errorf("bad token for %q: got %s, expected %s", lit, tok.String(), e.tok.String())
+			t.Errorf("bad token for %q: got %s, expected %s", lit, tok, e.tok)
 		}
 		if e.tok.IsLiteral() && lit != e.lit {
 			t.Errorf("bad literal for %q: got %q, expected %q", lit, lit, e.lit)
@@ -286,7 +286,7 @@ func checkSemi(t *testing.T, line string, mode uint) {
 				}
 				checkPos(t, line, pos, semiPos)
 			} else {
-				t.Errorf("bad token for %q: got %s, expected ;", line, tok.String())
+				t.Errorf("bad token for %q: got %s, expected ;", line, tok)
 			}
 		} else if tok == token.SEMICOLON {
 			t.Errorf("bad token for %q: got ;, expected no ;", line)
@@ -509,7 +509,7 @@ func TestInit(t *testing.T) {
 	s.Scan()              // true
 	_, tok, _ := s.Scan() // {
 	if tok != token.LBRACE {
-		t.Errorf("bad token: got %s, expected %s", tok.String(), token.LBRACE)
+		t.Errorf("bad token: got %s, expected %s", tok, token.LBRACE)
 	}
 
 	// 2nd init
@@ -521,7 +521,7 @@ func TestInit(t *testing.T) {
 	}
 	_, tok, _ = s.Scan() // go
 	if tok != token.GO {
-		t.Errorf("bad token: got %s, expected %s", tok.String(), token.GO)
+		t.Errorf("bad token: got %s, expected %s", tok, token.GO)
 	}
 
 	if s.ErrorCount != 0 {

src/pkg/gob/decode.go

@@ -881,7 +881,7 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string, inProg
 		}
 	}
 	if op == nil {
-		errorf("decode can't handle type %s", rt.String())
+		errorf("decode can't handle type %s", rt)
 	}
 	return &op, indir
 }
@@ -1110,7 +1110,7 @@ func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEn
 		wireStruct = wire.StructT
 	}
 	if wireStruct == nil {
-		errorf("type mismatch in decoder: want struct type %s; got non-struct", rt.String())
+		errorf("type mismatch in decoder: want struct type %s; got non-struct", rt)
 	}
 	engine = new(decEngine)
 	engine.instr = make([]decInstr, len(wireStruct.Field))

src/pkg/gob/encode.go

@@ -610,7 +610,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp
 		}
 	}
 	if op == nil {
-		errorf("can't happen: encode type %s", rt.String())
+		errorf("can't happen: encode type %s", rt)
 	}
 	return &op, indir
 }

src/pkg/smtp/smtp_test.go

@@ -37,14 +37,14 @@ testLoop:
 			t.Errorf("#%d got response %s, expected %s", i, resp, test.responses[0])
 		}
 		if err != nil {
-			t.Errorf("#%d error: %s", i, err.String())
+			t.Errorf("#%d error: %s", i, err)
 		}
 		for j := range test.challenges {
 			challenge := []byte(test.challenges[j])
 			expected := []byte(test.responses[j+1])
 			resp, err := test.auth.Next(challenge, true)
 			if err != nil {
-				t.Errorf("#%d error: %s", i, err.String())
+				t.Errorf("#%d error: %s", i, err)
 				continue testLoop
 			}
 			if !bytes.Equal(resp, expected) {
@@ -74,13 +74,13 @@ func TestBasic(t *testing.T) {
 	c := &Client{Text: textproto.NewConn(fake)}
 
 	if err := c.helo(); err != nil {
-		t.Fatalf("HELO failed: %s", err.String())
+		t.Fatalf("HELO failed: %s", err)
 	}
 	if err := c.ehlo(); err == nil {
 		t.Fatalf("Expected first EHLO to fail")
 	}
 	if err := c.ehlo(); err != nil {
-		t.Fatalf("Second EHLO failed: %s", err.String())
+		t.Fatalf("Second EHLO failed: %s", err)
 	}
 
 	if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
@@ -105,14 +105,14 @@ func TestBasic(t *testing.T) {
 	c.tls = true
 	c.serverName = "smtp.google.com"
 	if err := c.Auth(PlainAuth("", "user", "pass", "smtp.google.com")); err != nil {
-		t.Fatalf("AUTH failed: %s", err.String())
+		t.Fatalf("AUTH failed: %s", err)
 	}
 
 	if err := c.Mail("user@gmail.com"); err != nil {
-		t.Fatalf("MAIL failed: %s", err.String())
+		t.Fatalf("MAIL failed: %s", err)
 	}
 	if err := c.Rcpt("golang-nuts@googlegroups.com"); err != nil {
-		t.Fatalf("RCPT failed: %s", err.String())
+		t.Fatalf("RCPT failed: %s", err)
 	}
 	msg := `From: user@gmail.com
 To: golang-nuts@googlegroups.com
@@ -123,17 +123,17 @@ Line 1
 Goodbye.`
 	w, err := c.Data()
 	if err != nil {
-		t.Fatalf("DATA failed: %s", err.String())
+		t.Fatalf("DATA failed: %s", err)
 	}
 	if _, err := w.Write([]byte(msg)); err != nil {
-		t.Fatalf("Data write failed: %s", err.String())
+		t.Fatalf("Data write failed: %s", err)
 	}
 	if err := w.Close(); err != nil {
-		t.Fatalf("Bad data response: %s", err.String())
+		t.Fatalf("Bad data response: %s", err)
 	}
 
 	if err := c.Quit(); err != nil {
-		t.Fatalf("QUIT failed: %s", err.String())
+		t.Fatalf("QUIT failed: %s", err)
 	}
 
 	bcmdbuf.Flush()

src/pkg/strconv/fp_test.go

@@ -96,7 +96,7 @@ func myatof32(s string) (f float32, ok bool) {
 func TestFp(t *testing.T) {
 	f, err := os.Open("testfp.txt")
 	if err != nil {
-		t.Fatal("testfp: open testfp.txt:", err.String())
+		t.Fatal("testfp: open testfp.txt:", err)
 	}
 	defer f.Close()