all: excise some warts found by vet -shadow

These are not erroneous, just poor or confusing.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/10448043

src/cmd/go/get.go

@@ -286,7 +286,7 @@ func downloadPackage(p *Package) error {
 		}
 		// Some version control tools require the parent of the target to exist.
 		parent, _ := filepath.Split(root)
-		if err := os.MkdirAll(parent, 0777); err != nil {
+		if err = os.MkdirAll(parent, 0777); err != nil {
 			return err
 		}
 		if err = vcs.create(root, repo); err != nil {

src/pkg/encoding/asn1/marshal.go

@@ -441,11 +441,11 @@ func marshalBody(out *forkableWriter, value reflect.Value, params fieldParameter
 			return
 		}
 
-		var params fieldParameters
+		var fp fieldParameters
 		for i := 0; i < v.Len(); i++ {
 			var pre *forkableWriter
 			pre, out = out.fork()
-			err = marshalField(pre, v.Index(i), params)
+			err = marshalField(pre, v.Index(i), fp)
 			if err != nil {
 				return
 			}

src/pkg/encoding/gob/encode.go

@@ -575,21 +575,21 @@ func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp
 				break
 			}
 			// Slices have a header; we decode it to find the underlying array.
-			elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
+			elemOp, elemIndir := enc.encOpFor(t.Elem(), inProgress)
 			op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
 				slice := (*reflect.SliceHeader)(p)
 				if !state.sendZero && slice.Len == 0 {
 					return
 				}
 				state.update(i)
-				state.enc.encodeArray(state.b, unsafe.Pointer(slice.Data), *elemOp, t.Elem().Size(), indir, int(slice.Len))
+				state.enc.encodeArray(state.b, unsafe.Pointer(slice.Data), *elemOp, t.Elem().Size(), elemIndir, int(slice.Len))
 			}
 		case reflect.Array:
 			// True arrays have size in the type.
-			elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
+			elemOp, elemIndir := enc.encOpFor(t.Elem(), inProgress)
 			op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
 				state.update(i)
-				state.enc.encodeArray(state.b, p, *elemOp, t.Elem().Size(), indir, t.Len())
+				state.enc.encodeArray(state.b, p, *elemOp, t.Elem().Size(), elemIndir, t.Len())
 			}
 		case reflect.Map:
 			keyOp, keyIndir := enc.encOpFor(t.Key(), inProgress)

src/pkg/fmt/print.go

@@ -811,8 +811,8 @@ func (p *pp) printArg(arg interface{}, verb rune, plus, goSyntax bool, depth int
 		p.fmt.plus = oldPlus
 		p.fmt.sharp = oldSharp
 		// If the type is not simple, it might have methods.
-		if wasString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
+		if isString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
-			return wasString
+			return isString
 		}
 		// Need to use reflection
 		return p.printReflectValue(reflect.ValueOf(arg), verb, plus, goSyntax, depth)
@@ -849,8 +849,8 @@ func (p *pp) printValue(value reflect.Value, verb rune, plus, goSyntax bool, dep
 	if value.CanInterface() {
 		p.arg = value.Interface()
 	}
-	if wasString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
+	if isString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
-		return wasString
+		return isString
 	}
 
 	return p.printReflectValue(value, verb, plus, goSyntax, depth)

src/pkg/fmt/scan.go

@@ -781,7 +781,7 @@ func (s *ss) convertFloat(str string, n int) float64 {
 			}
 			s.error(err)
 		}
-		n, err := strconv.Atoi(str[p+1:])
+		m, err := strconv.Atoi(str[p+1:])
 		if err != nil {
 			// Put full string into error.
 			if e, ok := err.(*strconv.NumError); ok {
@@ -789,7 +789,7 @@ func (s *ss) convertFloat(str string, n int) float64 {
 			}
 			s.error(err)
 		}
-		return math.Ldexp(f, n)
+		return math.Ldexp(f, m)
 	}
 	f, err := strconv.ParseFloat(str, n)
 	if err != nil {
@@ -858,8 +858,7 @@ func (s *ss) quotedString() string {
 				// In a legal backslash escape, no matter how long, only the character
 				// immediately after the escape can itself be a backslash or quote.
 				// Thus we only need to protect the first character after the backslash.
-				r := s.mustReadRune()
+				s.buf.WriteRune(s.mustReadRune())
-				s.buf.WriteRune(r)
 			} else if r == '"' {
 				break
 			}

src/pkg/net/dial_test.go

@@ -381,7 +381,6 @@ func TestDialer(t *testing.T) {
 	defer ln.Close()
 	ch := make(chan error, 1)
 	go func() {
-		var err error
 		c, err := ln.Accept()
 		if err != nil {
 			ch <- fmt.Errorf("Accept failed: %v", err)

src/pkg/net/unix_test.go

@@ -212,7 +212,6 @@ func TestUnixgramConnLocalAndRemoteNames(t *testing.T) {
 
 		var la *UnixAddr
 		if laddr != "" {
-			var err error
 			if la, err = ResolveUnixAddr("unixgram", laddr); err != nil {
 				t.Fatalf("ResolveUnixAddr failed: %v", err)
 			}

src/pkg/os/path_test.go

@@ -91,7 +91,7 @@ func TestRemoveAll(t *testing.T) {
 	if err = RemoveAll(path); err != nil {
 		t.Fatalf("RemoveAll %q (first): %s", path, err)
 	}
-	if _, err := Lstat(path); err == nil {
+	if _, err = Lstat(path); err == nil {
 		t.Fatalf("Lstat %q succeeded after RemoveAll (first)", path)
 	}
 
@@ -153,7 +153,7 @@ func TestRemoveAll(t *testing.T) {
 		Chmod(dpath, 0777)
 
 		for _, s := range []string{fpath, path + "/zzz"} {
-			if _, err := Lstat(s); err == nil {
+			if _, err = Lstat(s); err == nil {
 				t.Fatalf("Lstat %q succeeded after partial RemoveAll", s)
 			}
 		}
@@ -161,7 +161,7 @@ func TestRemoveAll(t *testing.T) {
 	if err = RemoveAll(path); err != nil {
 		t.Fatalf("RemoveAll %q after partial RemoveAll: %s", path, err)
 	}
-	if _, err := Lstat(path); err == nil {
+	if _, err = Lstat(path); err == nil {
 		t.Fatalf("Lstat %q succeeded after RemoveAll (final)", path)
 	}
 }

src/pkg/syscall/syscall_bsd.go

@@ -532,10 +532,9 @@ func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
 	var ptr uintptr
 	var salen _Socklen
 	if to != nil {
-		var err error
 		ptr, salen, err = to.sockaddr()
 		if err != nil {
-			return err
+			return
 		}
 	}
 	var msg Msghdr

src/pkg/time/format.go

@@ -780,7 +780,7 @@ func parse(layout, value string, defaultLocation, local *Location) (Time, error)
 			// Special case: do we have a fractional second but no
 			// fractional second in the format?
 			if len(value) >= 2 && value[0] == '.' && isDigit(value, 1) {
-				_, std, _ := nextStdChunk(layout)
+				_, std, _ = nextStdChunk(layout)
 				std &= stdMask
 				if std == stdFracSecond0 || std == stdFracSecond9 {
 					// Fractional second in the layout; proceed normally