all: remove unnecessary type conversions

cmd and runtime were handled separately, and I'm intentionally skipped
syscall. This is the rest of the standard library.

CL generated mechanically with github.com/mdempsky/unconvert.

Change-Id: I9e0eff886974dedc37adb93f602064b83e469122
Reviewed-on: https://go-review.googlesource.com/22104
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

50 files changed, 120 insertions, 120 deletions

diff --git a/src/archive/tar/reader.go b/src/archive/tar/reader.go
index 741fe0152b..b924eeb568 100644
--- a/src/archive/tar/reader.go
+++ b/src/archive/tar/reader.go
@@ -306,7 +306,7 @@ func mergePAX(hdr *Header, headers map[string]string) error {
 			if err != nil {
 				return err
 			}
-			hdr.Size = int64(size)
+			hdr.Size = size
 		default:
 			if strings.HasPrefix(k, paxXattr) {
 				if hdr.Xattrs == nil {
@@ -346,7 +346,7 @@ func parsePAXTime(t string) (time.Time, error) {
 			// Right truncate
 			nano_buf = nano_buf[:maxNanoSecondIntSize]
 		}
-		nanoseconds, err = strconv.ParseInt(string(nano_buf), 10, 0)
+		nanoseconds, err = strconv.ParseInt(nano_buf, 10, 0)
 		if err != nil {
 			return time.Time{}, err
 		}
@@ -378,14 +378,14 @@ func parsePAX(r io.Reader) (map[string]string, error) {
 		}
 		sbuf = residual
 
-		keyStr := string(key)
+		keyStr := key
 		if keyStr == paxGNUSparseOffset || keyStr == paxGNUSparseNumBytes {
 			// GNU sparse format 0.0 special key. Write to sparseMap instead of using the headers map.
 			sparseMap.WriteString(value)
 			sparseMap.Write([]byte{','})
 		} else {
 			// Normal key. Set the value in the headers map.
-			headers[keyStr] = string(value)
+			headers[keyStr] = value
 		}
 	}
 	if sparseMap.Len() != 0 {
diff --git a/src/archive/tar/writer.go b/src/archive/tar/writer.go
index 600ee4be09..944b2d4952 100644
--- a/src/archive/tar/writer.go
+++ b/src/archive/tar/writer.go
@@ -278,7 +278,7 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 			return err
 		}
 	}
-	tw.nb = int64(hdr.Size)
+	tw.nb = hdr.Size
 	tw.pad = (blockSize - (tw.nb % blockSize)) % blockSize
 
 	_, tw.err = tw.w.Write(header)
diff --git a/src/bytes/reader.go b/src/bytes/reader.go
index 7aa30578b3..aa39890f3b 100644
--- a/src/bytes/reader.go
+++ b/src/bytes/reader.go
@@ -114,7 +114,7 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	case 0:
 		abs = offset
 	case 1:
-		abs = int64(r.i) + offset
+		abs = r.i + offset
 	case 2:
 		abs = int64(len(r.s)) + offset
 	default:
diff --git a/src/compress/bzip2/bzip2.go b/src/compress/bzip2/bzip2.go
index 90e9aebab6..42788443bc 100644
--- a/src/compress/bzip2/bzip2.go
+++ b/src/compress/bzip2/bzip2.go
@@ -75,7 +75,7 @@ func (bz2 *reader) setup(needMagic bool) error {
 	}
 
 	bz2.fileCRC = 0
-	bz2.blockSize = 100 * 1000 * (int(level) - '0')
+	bz2.blockSize = 100 * 1000 * (level - '0')
 	if bz2.blockSize > len(bz2.tt) {
 		bz2.tt = make([]uint32, bz2.blockSize)
 	}
@@ -293,7 +293,7 @@ func (bz2 *reader) readBlock() (err error) {
 		if c >= numHuffmanTrees {
 			return StructuralError("tree index too large")
 		}
-		treeIndexes[i] = uint8(mtfTreeDecoder.Decode(c))
+		treeIndexes[i] = mtfTreeDecoder.Decode(c)
 	}
 
 	// The list of symbols for the move-to-front transform is taken from
@@ -399,7 +399,7 @@ func (bz2 *reader) readBlock() (err error) {
 				return StructuralError("repeats past end of block")
 			}
 			for i := 0; i < repeat; i++ {
-				b := byte(mtf.First())
+				b := mtf.First()
 				bz2.tt[bufIndex] = uint32(b)
 				bz2.c[b]++
 				bufIndex++
@@ -420,7 +420,7 @@ func (bz2 *reader) readBlock() (err error) {
 		// it's always referenced with a run-length of 1. Thus 0
 		// doesn't need to be encoded and we have |v-1| in the next
 		// line.
-		b := byte(mtf.Decode(int(v - 1)))
+		b := mtf.Decode(int(v - 1))
 		if bufIndex >= bz2.blockSize {
 			return StructuralError("data exceeds block size")
 		}
diff --git a/src/compress/flate/huffman_bit_writer.go b/src/compress/flate/huffman_bit_writer.go
index 23f242f88e..d0206e59cf 100644
--- a/src/compress/flate/huffman_bit_writer.go
+++ b/src/compress/flate/huffman_bit_writer.go
@@ -436,7 +436,7 @@ func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
 	}
 	dynamicHeader := int64(3+5+5+4+(3*numCodegens)) +
 		w.codegenEncoding.bitLength(w.codegenFreq[:]) +
-		int64(extraBits) +
+		extraBits +
 		int64(w.codegenFreq[16]*2) +
 		int64(w.codegenFreq[17]*3) +
 		int64(w.codegenFreq[18]*7)
diff --git a/src/compress/flate/reverse_bits.go b/src/compress/flate/reverse_bits.go
index c1a02720d1..6b222900c1 100644
--- a/src/compress/flate/reverse_bits.go
+++ b/src/compress/flate/reverse_bits.go
@@ -44,5 +44,5 @@ func reverseUint16(v uint16) uint16 {
 }
 
 func reverseBits(number uint16, bitLength byte) uint16 {
-	return reverseUint16(number << uint8(16-bitLength))
+	return reverseUint16(number << (16 - bitLength))
 }
diff --git a/src/compress/lzw/writer.go b/src/compress/lzw/writer.go
index 7367c29651..6ddb335f31 100644
--- a/src/compress/lzw/writer.go
+++ b/src/compress/lzw/writer.go
@@ -119,7 +119,7 @@ func (e *encoder) incHi() error {
 		if err := e.write(e, clear); err != nil {
 			return err
 		}
-		e.width = uint(e.litWidth) + 1
+		e.width = e.litWidth + 1
 		e.hi = clear + 1
 		e.overflow = clear << 1
 		for i := range e.table {
diff --git a/src/crypto/des/block.go b/src/crypto/des/block.go
index 26355a22e7..99338d62a6 100644
--- a/src/crypto/des/block.go
+++ b/src/crypto/des/block.go
@@ -72,7 +72,7 @@ func init() {
 		for i := 0; i < 4; i++ {
 			for j := 0; j < 16; j++ {
 				f := uint64(sBoxes[s][i][j]) << (4 * (7 - uint(s)))
-				f = permuteBlock(uint64(f), permutationFunction[:])
+				f = permuteBlock(f, permutationFunction[:])
 				feistelBox[s][16*i+j] = uint32(f)
 			}
 		}
diff --git a/src/crypto/tls/handshake_messages.go b/src/crypto/tls/handshake_messages.go
index 13d013a594..3f9a63b110 100644
--- a/src/crypto/tls/handshake_messages.go
+++ b/src/crypto/tls/handshake_messages.go
@@ -214,7 +214,7 @@ func (m *clientHelloMsg) marshal() []byte {
 		z[4] = byte(l)
 		z = z[5:]
 		for _, pointFormat := range m.supportedPoints {
-			z[0] = byte(pointFormat)
+			z[0] = pointFormat
 			z = z[1:]
 		}
 	}
@@ -589,7 +589,7 @@ func (m *serverHelloMsg) marshal() []byte {
 	z := x[39+len(m.sessionId):]
 	z[0] = uint8(m.cipherSuite >> 8)
 	z[1] = uint8(m.cipherSuite)
-	z[2] = uint8(m.compressionMethod)
+	z[2] = m.compressionMethod
 
 	z = z[3:]
 	if numExtensions > 0 {
diff --git a/src/debug/dwarf/buf.go b/src/debug/dwarf/buf.go
index 7443043c11..24d266db10 100644
--- a/src/debug/dwarf/buf.go
+++ b/src/debug/dwarf/buf.go
@@ -157,7 +157,7 @@ func (b *buf) addr() uint64 {
 	case 4:
 		return uint64(b.uint32())
 	case 8:
-		return uint64(b.uint64())
+		return b.uint64()
 	}
 	b.error("unknown address size")
 	return 0
diff --git a/src/debug/dwarf/line.go b/src/debug/dwarf/line.go
index b3b91ade62..ed82feef92 100644
--- a/src/debug/dwarf/line.go
+++ b/src/debug/dwarf/line.go
@@ -361,7 +361,7 @@ func (r *LineReader) step(entry *LineEntry) bool {
 		// Special opcode [DWARF2 6.2.5.1, DWARF4 6.2.5.1]
 		adjustedOpcode := opcode - r.opcodeBase
 		r.advancePC(adjustedOpcode / r.lineRange)
-		lineDelta := r.lineBase + int(adjustedOpcode)%r.lineRange
+		lineDelta := r.lineBase + adjustedOpcode%r.lineRange
 		r.state.Line += lineDelta
 		goto emit
 	}
diff --git a/src/debug/dwarf/typeunit.go b/src/debug/dwarf/typeunit.go
index ed42547386..652e02d917 100644
--- a/src/debug/dwarf/typeunit.go
+++ b/src/debug/dwarf/typeunit.go
@@ -76,7 +76,7 @@ func (d *Data) parseTypes(name string, types []byte) error {
 				data:   b.bytes(int(n - (b.off - hdroff))),
 				atable: atable,
 				asize:  int(asize),
-				vers:   int(vers),
+				vers:   vers,
 				is64:   dwarf64,
 			},
 			toff: Offset(toff),
@@ -101,7 +101,7 @@ func (d *Data) sigToType(sig uint64) (Type, error) {
 
 	b := makeBuf(d, tu, tu.name, tu.off, tu.data)
 	r := &typeUnitReader{d: d, tu: tu, b: b}
-	t, err := d.readType(tu.name, r, Offset(tu.toff), make(map[Offset]Type), nil)
+	t, err := d.readType(tu.name, r, tu.toff, make(map[Offset]Type), nil)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/debug/elf/elf.go b/src/debug/elf/elf.go
index af881c2495..3f43d4d896 100644
--- a/src/debug/elf/elf.go
+++ b/src/debug/elf/elf.go
@@ -2060,8 +2060,8 @@ type Rela32 struct {
 	Addend int32  /* Addend. */
 }
 
-func R_SYM32(info uint32) uint32      { return uint32(info >> 8) }
-func R_TYPE32(info uint32) uint32     { return uint32(info & 0xff) }
+func R_SYM32(info uint32) uint32      { return info >> 8 }
+func R_TYPE32(info uint32) uint32     { return info & 0xff }
 func R_INFO32(sym, typ uint32) uint32 { return sym<<8 | typ }
 
 // ELF32 Symbol.
diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index 8fbf23fe5a..c173ea9331 100644
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -294,7 +294,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		}
 		f.Type = Type(hdr.Type)
 		f.Machine = Machine(hdr.Machine)
-		f.Entry = uint64(hdr.Entry)
+		f.Entry = hdr.Entry
 		if v := Version(hdr.Version); v != f.Version {
 			return nil, &FormatError{0, "mismatched ELF version", v}
 		}
@@ -341,12 +341,12 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			p.ProgHeader = ProgHeader{
 				Type:   ProgType(ph.Type),
 				Flags:  ProgFlag(ph.Flags),
-				Off:    uint64(ph.Off),
-				Vaddr:  uint64(ph.Vaddr),
-				Paddr:  uint64(ph.Paddr),
-				Filesz: uint64(ph.Filesz),
-				Memsz:  uint64(ph.Memsz),
-				Align:  uint64(ph.Align),
+				Off:    ph.Off,
+				Vaddr:  ph.Vaddr,
+				Paddr:  ph.Paddr,
+				Filesz: ph.Filesz,
+				Memsz:  ph.Memsz,
+				Align:  ph.Align,
 			}
 		}
 		p.sr = io.NewSectionReader(r, int64(p.Off), int64(p.Filesz))
@@ -374,8 +374,8 @@ func NewFile(r io.ReaderAt) (*File, error) {
 				Addr:      uint64(sh.Addr),
 				Offset:    uint64(sh.Off),
 				FileSize:  uint64(sh.Size),
-				Link:      uint32(sh.Link),
-				Info:      uint32(sh.Info),
+				Link:      sh.Link,
+				Info:      sh.Info,
 				Addralign: uint64(sh.Addralign),
 				Entsize:   uint64(sh.Entsize),
 			}
@@ -388,13 +388,13 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			s.SectionHeader = SectionHeader{
 				Type:      SectionType(sh.Type),
 				Flags:     SectionFlag(sh.Flags),
-				Offset:    uint64(sh.Off),
-				FileSize:  uint64(sh.Size),
-				Addr:      uint64(sh.Addr),
-				Link:      uint32(sh.Link),
-				Info:      uint32(sh.Info),
-				Addralign: uint64(sh.Addralign),
-				Entsize:   uint64(sh.Entsize),
+				Offset:    sh.Off,
+				FileSize:  sh.Size,
+				Addr:      sh.Addr,
+				Link:      sh.Link,
+				Info:      sh.Info,
+				Addralign: sh.Addralign,
+				Entsize:   sh.Entsize,
 			}
 		}
 		s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.FileSize))
diff --git a/src/debug/gosym/pclntab.go b/src/debug/gosym/pclntab.go
index 291f102262..e859d5aed5 100644
--- a/src/debug/gosym/pclntab.go
+++ b/src/debug/gosym/pclntab.go
@@ -207,8 +207,8 @@ func (t *LineTable) go12Funcs() []Func {
 	funcs := make([]Func, n)
 	for i := range funcs {
 		f := &funcs[i]
-		f.Entry = uint64(t.uintptr(t.functab[2*i*int(t.ptrsize):]))
-		f.End = uint64(t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):]))
+		f.Entry = t.uintptr(t.functab[2*i*int(t.ptrsize):])
+		f.End = t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):])
 		info := t.Data[t.uintptr(t.functab[(2*i+1)*int(t.ptrsize):]):]
 		f.LineTable = t
 		f.FrameSize = int(t.binary.Uint32(info[t.ptrsize+2*4:]))
diff --git a/src/debug/gosym/symtab.go b/src/debug/gosym/symtab.go
index 49e154fd8e..c8fa9a0b38 100644
--- a/src/debug/gosym/symtab.go
+++ b/src/debug/gosym/symtab.go
@@ -294,8 +294,8 @@ func NewTable(symtab []byte, pcln *LineTable) (*Table, error) {
 		t.Syms = t.Syms[0 : n+1]
 		ts := &t.Syms[n]
 		ts.Type = s.typ
-		ts.Value = uint64(s.value)
-		ts.GoType = uint64(s.gotype)
+		ts.Value = s.value
+		ts.GoType = s.gotype
 		switch s.typ {
 		default:
 			// rewrite name to use . instead of · (c2 b7)
diff --git a/src/encoding/asn1/marshal.go b/src/encoding/asn1/marshal.go
index 2b796c4e75..30797ef099 100644
--- a/src/encoding/asn1/marshal.go
+++ b/src/encoding/asn1/marshal.go
@@ -315,9 +315,9 @@ func marshalUTCTime(out *forkableWriter, t time.Time) (err error) {
 
 	switch {
 	case 1950 <= year && year < 2000:
-		err = marshalTwoDigits(out, int(year-1900))
+		err = marshalTwoDigits(out, year-1900)
 	case 2000 <= year && year < 2050:
-		err = marshalTwoDigits(out, int(year-2000))
+		err = marshalTwoDigits(out, year-2000)
 	default:
 		return StructuralError{"cannot represent time as UTCTime"}
 	}
@@ -435,7 +435,7 @@ func marshalBody(out *forkableWriter, value reflect.Value, params fieldParameter
 			return out.WriteByte(0)
 		}
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return marshalInt64(out, int64(v.Int()))
+		return marshalInt64(out, v.Int())
 	case reflect.Struct:
 		t := v.Type()
 
diff --git a/src/encoding/binary/binary.go b/src/encoding/binary/binary.go
index ada5768695..46c6add062 100644
--- a/src/encoding/binary/binary.go
+++ b/src/encoding/binary/binary.go
@@ -269,7 +269,7 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
 		case *uint8:
 			b[0] = *v
 		case uint8:
-			b[0] = byte(v)
+			b[0] = v
 		case []uint8:
 			bs = v
 		case *int16:
diff --git a/src/encoding/gob/encode.go b/src/encoding/gob/encode.go
index 2b3a556eac..50cd6adb46 100644
--- a/src/encoding/gob/encode.go
+++ b/src/encoding/gob/encode.go
@@ -127,7 +127,7 @@ func (state *encoderState) encodeInt(i int64) {
 	} else {
 		x = uint64(i << 1)
 	}
-	state.encodeUint(uint64(x))
+	state.encodeUint(x)
 }
 
 // encOp is the signature of an encoding operator for a given type.
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 5ab4283826..cca2d48bbd 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -99,7 +99,7 @@ func (g *CommentGroup) Text() string {
 	}
 	comments := make([]string, len(g.List))
 	for i, c := range g.List {
-		comments[i] = string(c.Text)
+		comments[i] = c.Text
 	}
 
 	lines := make([]string, 0, 10) // most comments are less than 10 lines
diff --git a/src/image/color/ycbcr.go b/src/image/color/ycbcr.go
index d2c5b569a7..2e985fece1 100644
--- a/src/image/color/ycbcr.go
+++ b/src/image/color/ycbcr.go
@@ -237,10 +237,10 @@ func RGBToCMYK(r, g, b uint8) (uint8, uint8, uint8, uint8) {
 
 // CMYKToRGB converts a CMYK quadruple to an RGB triple.
 func CMYKToRGB(c, m, y, k uint8) (uint8, uint8, uint8) {
-	w := uint32(0xffff - uint32(k)*0x101)
-	r := uint32(0xffff-uint32(c)*0x101) * w / 0xffff
-	g := uint32(0xffff-uint32(m)*0x101) * w / 0xffff
-	b := uint32(0xffff-uint32(y)*0x101) * w / 0xffff
+	w := 0xffff - uint32(k)*0x101
+	r := (0xffff - uint32(c)*0x101) * w / 0xffff
+	g := (0xffff - uint32(m)*0x101) * w / 0xffff
+	b := (0xffff - uint32(y)*0x101) * w / 0xffff
 	return uint8(r >> 8), uint8(g >> 8), uint8(b >> 8)
 }
 
@@ -256,11 +256,11 @@ func (c CMYK) RGBA() (uint32, uint32, uint32, uint32) {
 	// This code is a copy of the CMYKToRGB function above, except that it
 	// returns values in the range [0, 0xffff] instead of [0, 0xff].
 
-	w := uint32(0xffff - uint32(c.K)*0x101)
-	r := uint32(0xffff-uint32(c.C)*0x101) * w / 0xffff
-	g := uint32(0xffff-uint32(c.M)*0x101) * w / 0xffff
-	b := uint32(0xffff-uint32(c.Y)*0x101) * w / 0xffff
-	return uint32(r), uint32(g), uint32(b), 0xffff
+	w := 0xffff - uint32(c.K)*0x101
+	r := (0xffff - uint32(c.C)*0x101) * w / 0xffff
+	g := (0xffff - uint32(c.M)*0x101) * w / 0xffff
+	b := (0xffff - uint32(c.Y)*0x101) * w / 0xffff
+	return r, g, b, 0xffff
 }
 
 // CMYKModel is the Model for CMYK colors.
diff --git a/src/image/draw/draw.go b/src/image/draw/draw.go
index 94e3575663..6a16cd39cf 100644
--- a/src/image/draw/draw.go
+++ b/src/image/draw/draw.go
@@ -634,10 +634,10 @@ func drawPaletted(dst Image, r image.Rectangle, src image.Image, sp image.Point,
 				if !floydSteinberg {
 					continue
 				}
-				er -= int32(palette[bestIndex][0])
-				eg -= int32(palette[bestIndex][1])
-				eb -= int32(palette[bestIndex][2])
-				ea -= int32(palette[bestIndex][3])
+				er -= palette[bestIndex][0]
+				eg -= palette[bestIndex][1]
+				eb -= palette[bestIndex][2]
+				ea -= palette[bestIndex][3]
 
 			} else {
 				out.R = uint16(er)
diff --git a/src/math/big/float.go b/src/math/big/float.go
index 4b8ad388d3..7a9c2b3dfb 100644
--- a/src/math/big/float.go
+++ b/src/math/big/float.go
@@ -1008,9 +1008,9 @@ func (x *Float) Float64() (float64, Accuracy) {
 		if r.form == inf || e > emax {
 			// overflow
 			if x.neg {
-				return float64(math.Inf(-1)), Below
+				return math.Inf(-1), Below
 			}
-			return float64(math.Inf(+1)), Above
+			return math.Inf(+1), Above
 		}
 		// e <= emax
 
diff --git a/src/math/big/natconv.go b/src/math/big/natconv.go
index d2ce667fb6..e216bd288c 100644
--- a/src/math/big/natconv.go
+++ b/src/math/big/natconv.go
@@ -302,7 +302,7 @@ func (x nat) itoa(neg bool, base int) []byte {
 		}
 
 	} else {
-		bb, ndigits := maxPow(Word(b))
+		bb, ndigits := maxPow(b)
 
 		// construct table of successive squares of bb*leafSize to use in subdivisions
 		// result (table != nil) <=> (len(x) > leafSize > 0)
diff --git a/src/math/big/ratconv.go b/src/math/big/ratconv.go
index 57df124e88..7c127f8585 100644
--- a/src/math/big/ratconv.go
+++ b/src/math/big/ratconv.go
@@ -178,7 +178,7 @@ func scanExponent(r io.ByteScanner, binExpOk bool) (exp int64, base int, err err
 			}
 			break // i > 0
 		}
-		digits = append(digits, byte(ch))
+		digits = append(digits, ch)
 	}
 	// i > 0 => we have at least one digit
 
diff --git a/src/net/interface_bsd.go b/src/net/interface_bsd.go
index b173fbcefc..17c6dd3dcd 100644
--- a/src/net/interface_bsd.go
+++ b/src/net/interface_bsd.go
@@ -61,13 +61,13 @@ func newLink(m *syscall.InterfaceMessage) (*Interface, error) {
 		m.Data = m.Data[unsafe.Offsetof(sa.Data):]
 		var name [syscall.IFNAMSIZ]byte
 		for i := 0; i < int(sa.Nlen); i++ {
-			name[i] = byte(m.Data[i])
+			name[i] = m.Data[i]
 		}
 		ifi.Name = string(name[:sa.Nlen])
 		ifi.MTU = int(m.Header.Data.Mtu)
 		addr := make([]byte, sa.Alen)
 		for i := 0; i < int(sa.Alen); i++ {
-			addr[i] = byte(m.Data[int(sa.Nlen)+i])
+			addr[i] = m.Data[int(sa.Nlen)+i]
 		}
 		ifi.HardwareAddr = addr[:sa.Alen]
 	}
diff --git a/src/net/mail/message.go b/src/net/mail/message.go
index 9e3a103a4f..b40a314e33 100644
--- a/src/net/mail/message.go
+++ b/src/net/mail/message.go
@@ -477,7 +477,7 @@ func (p *addrParser) consumeAtom(dot bool, permissive bool) (atom string, err er
 	if i < p.len() && p.s[i] > 127 {
 		return "", errNonASCII
 	}
-	atom, p.s = string(p.s[:i]), p.s[i:]
+	atom, p.s = p.s[:i], p.s[i:]
 	if !permissive {
 		if strings.HasPrefix(atom, ".") {
 			return "", errors.New("mail: leading dot in atom")
diff --git a/src/net/parse.go b/src/net/parse.go
index eaaa1edf30..ed82a7769b 100644
--- a/src/net/parse.go
+++ b/src/net/parse.go
@@ -105,14 +105,14 @@ func splitAtBytes(s string, t string) []string {
 	for i := 0; i < len(s); i++ {
 		if byteIndex(t, s[i]) >= 0 {
 			if last < i {
-				a[n] = string(s[last:i])
+				a[n] = s[last:i]
 				n++
 			}
 			last = i + 1
 		}
 	}
 	if last < len(s) {
-		a[n] = string(s[last:])
+		a[n] = s[last:]
 		n++
 	}
 	return a[0:n]
diff --git a/src/os/exec_windows.go b/src/os/exec_windows.go
index 3264271b2e..72b5a93199 100644
--- a/src/os/exec_windows.go
+++ b/src/os/exec_windows.go
@@ -104,7 +104,7 @@ func init() {
 	defer syscall.LocalFree(syscall.Handle(uintptr(unsafe.Pointer(argv))))
 	Args = make([]string, argc)
 	for i, v := range (*argv)[:argc] {
-		Args[i] = string(syscall.UTF16ToString((*v)[:]))
+		Args[i] = syscall.UTF16ToString((*v)[:])
 	}
 }
 
diff --git a/src/os/file_windows.go b/src/os/file_windows.go
index 7d04477d42..137f24a0a9 100644
--- a/src/os/file_windows.go
+++ b/src/os/file_windows.go
@@ -181,9 +181,9 @@ func (file *file) close() error {
 	}
 	var e error
 	if file.isdir() {
-		e = syscall.FindClose(syscall.Handle(file.fd))
+		e = syscall.FindClose(file.fd)
 	} else {
-		e = syscall.CloseHandle(syscall.Handle(file.fd))
+		e = syscall.CloseHandle(file.fd)
 	}
 	var err error
 	if e != nil {
@@ -216,7 +216,7 @@ func (file *File) readdir(n int) (fi []FileInfo, err error) {
 	d := &file.dirinfo.data
 	for n != 0 && !file.dirinfo.isempty {
 		if file.dirinfo.needdata {
-			e := syscall.FindNextFile(syscall.Handle(file.fd), d)
+			e := syscall.FindNextFile(file.fd, d)
 			if e != nil {
 				if e == syscall.ERROR_NO_MORE_FILES {
 					break
@@ -230,7 +230,7 @@ func (file *File) readdir(n int) (fi []FileInfo, err error) {
 			}
 		}
 		file.dirinfo.needdata = true
-		name := string(syscall.UTF16ToString(d.FileName[0:]))
+		name := syscall.UTF16ToString(d.FileName[0:])
 		if name == "." || name == ".." { // Useless names
 			continue
 		}
@@ -288,7 +288,7 @@ func (f *File) readConsole(b []byte) (n int, err error) {
 			}
 			wchars := make([]uint16, nwc)
 			pwc := &wchars[0]
-			nwc, err = windows.MultiByteToWideChar(acp, 2, pmb, int32(nmb), pwc, int32(nwc))
+			nwc, err = windows.MultiByteToWideChar(acp, 2, pmb, int32(nmb), pwc, nwc)
 			if err != nil {
 				return 0, err
 			}
@@ -335,7 +335,7 @@ func (f *File) pread(b []byte, off int64) (n int, err error) {
 		Offset:     uint32(off),
 	}
 	var done uint32
-	e = syscall.ReadFile(syscall.Handle(f.fd), b, &done, &o)
+	e = syscall.ReadFile(f.fd, b, &done, &o)
 	if e != nil {
 		if e == syscall.ERROR_HANDLE_EOF {
 			// end of file
@@ -415,7 +415,7 @@ func (f *File) pwrite(b []byte, off int64) (n int, err error) {
 		Offset:     uint32(off),
 	}
 	var done uint32
-	e = syscall.WriteFile(syscall.Handle(f.fd), b, &done, &o)
+	e = syscall.WriteFile(f.fd, b, &done, &o)
 	if e != nil {
 		return 0, e
 	}
diff --git a/src/os/stat_darwin.go b/src/os/stat_darwin.go
index 9dc7a99fb7..74214cefa4 100644
--- a/src/os/stat_darwin.go
+++ b/src/os/stat_darwin.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtimespec)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
diff --git a/src/os/stat_dragonfly.go b/src/os/stat_dragonfly.go
index 69e63230eb..217bc6726d 100644
--- a/src/os/stat_dragonfly.go
+++ b/src/os/stat_dragonfly.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtim)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
@@ -42,7 +42,7 @@ func fillFileStatFromSys(fs *fileStat, name string) {
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
-	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
+	return time.Unix(ts.Sec, ts.Nsec)
 }
 
 // For testing.
diff --git a/src/os/stat_freebsd.go b/src/os/stat_freebsd.go
index e9d38aa722..bab4ffa798 100644
--- a/src/os/stat_freebsd.go
+++ b/src/os/stat_freebsd.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtimespec)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
diff --git a/src/os/stat_linux.go b/src/os/stat_linux.go
index 69e63230eb..d36afa9ffd 100644
--- a/src/os/stat_linux.go
+++ b/src/os/stat_linux.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtim)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
diff --git a/src/os/stat_nacl.go b/src/os/stat_nacl.go
index d3bed14e43..0c53f2faa4 100644
--- a/src/os/stat_nacl.go
+++ b/src/os/stat_nacl.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtime, fs.sys.MtimeNsec)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
diff --git a/src/os/stat_netbsd.go b/src/os/stat_netbsd.go
index e9d38aa722..11ebcacab8 100644
--- a/src/os/stat_netbsd.go
+++ b/src/os/stat_netbsd.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtimespec)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
@@ -42,7 +42,7 @@ func fillFileStatFromSys(fs *fileStat, name string) {
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
-	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
+	return time.Unix(ts.Sec, int64(ts.Nsec))
 }
 
 // For testing.
diff --git a/src/os/stat_openbsd.go b/src/os/stat_openbsd.go
index 69e63230eb..9df2d7f773 100644
--- a/src/os/stat_openbsd.go
+++ b/src/os/stat_openbsd.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtim)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
@@ -42,7 +42,7 @@ func fillFileStatFromSys(fs *fileStat, name string) {
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
-	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
+	return time.Unix(ts.Sec, int64(ts.Nsec))
 }
 
 // For testing.
diff --git a/src/os/stat_plan9.go b/src/os/stat_plan9.go
index a2df5fe139..96f056c111 100644
--- a/src/os/stat_plan9.go
+++ b/src/os/stat_plan9.go
@@ -20,7 +20,7 @@ func sameFile(fs1, fs2 *fileStat) bool {
 func fileInfoFromStat(d *syscall.Dir) FileInfo {
 	fs := &fileStat{
 		name:    d.Name,
-		size:    int64(d.Length),
+		size:    d.Length,
 		modTime: time.Unix(int64(d.Mtime), 0),
 		sys:     d,
 	}
diff --git a/src/os/stat_solaris.go b/src/os/stat_solaris.go
index 69e63230eb..217bc6726d 100644
--- a/src/os/stat_solaris.go
+++ b/src/os/stat_solaris.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtim)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
@@ -42,7 +42,7 @@ func fillFileStatFromSys(fs *fileStat, name string) {
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
-	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
+	return time.Unix(ts.Sec, ts.Nsec)
 }
 
 // For testing.
diff --git a/src/os/stat_windows.go b/src/os/stat_windows.go
index b8f97ad60a..e55eeb0fdd 100644
--- a/src/os/stat_windows.go
+++ b/src/os/stat_windows.go
@@ -35,7 +35,7 @@ func (file *File) Stat() (FileInfo, error) {
 	}
 
 	var d syscall.ByHandleFileInformation
-	err = syscall.GetFileInformationByHandle(syscall.Handle(file.fd), &d)
+	err = syscall.GetFileInformationByHandle(file.fd, &d)
 	if err != nil {
 		return nil, &PathError{"GetFileInformationByHandle", file.name, err}
 	}
diff --git a/src/os/types_windows.go b/src/os/types_windows.go
index 900d444b0e..ad4e863fcb 100644
--- a/src/os/types_windows.go
+++ b/src/os/types_windows.go
@@ -73,7 +73,7 @@ func (fs *fileStat) loadFileId() error {
 	}
 	defer syscall.CloseHandle(h)
 	var i syscall.ByHandleFileInformation
-	err = syscall.GetFileInformationByHandle(syscall.Handle(h), &i)
+	err = syscall.GetFileInformationByHandle(h, &i)
 	if err != nil {
 		return err
 	}
diff --git a/src/reflect/type.go b/src/reflect/type.go
index 3c7affcd7f..b8c778cc2b 100644
--- a/src/reflect/type.go
+++ b/src/reflect/type.go
@@ -967,7 +967,7 @@ func (t *rtype) Out(i int) Type {
 }
 
 func (t *funcType) in() []*rtype {
-	uadd := uintptr(unsafe.Sizeof(*t))
+	uadd := unsafe.Sizeof(*t)
 	if t.tflag&tflagUncommon != 0 {
 		uadd += unsafe.Sizeof(uncommonType{})
 	}
@@ -975,7 +975,7 @@ func (t *funcType) in() []*rtype {
 }
 
 func (t *funcType) out() []*rtype {
-	uadd := uintptr(unsafe.Sizeof(*t))
+	uadd := unsafe.Sizeof(*t)
 	if t.tflag&tflagUncommon != 0 {
 		uadd += unsafe.Sizeof(uncommonType{})
 	}
diff --git a/src/reflect/value.go b/src/reflect/value.go
index d72c14e9e1..d4d317436a 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -666,7 +666,7 @@ func (v Value) Cap() int {
 	case Array:
 		return v.typ.Len()
 	case Chan:
-		return int(chancap(v.pointer()))
+		return chancap(v.pointer())
 	case Slice:
 		// Slice is always bigger than a word; assume flagIndir.
 		return (*sliceHeader)(v.ptr).Cap
@@ -885,7 +885,7 @@ func (v Value) Int() int64 {
 	case Int32:
 		return int64(*(*int32)(p))
 	case Int64:
-		return int64(*(*int64)(p))
+		return *(*int64)(p)
 	}
 	panic(&ValueError{"reflect.Value.Int", v.kind()})
 }
@@ -1436,7 +1436,7 @@ func (v Value) SetCap(n int) {
 	v.mustBeAssignable()
 	v.mustBe(Slice)
 	s := (*sliceHeader)(v.ptr)
-	if n < int(s.Len) || n > int(s.Cap) {
+	if n < s.Len || n > s.Cap {
 		panic("reflect: slice capacity out of range in SetCap")
 	}
 	s.Cap = n
@@ -1538,7 +1538,7 @@ func (v Value) Slice(i, j int) Value {
 	case Slice:
 		typ = (*sliceType)(unsafe.Pointer(v.typ))
 		s := (*sliceHeader)(v.ptr)
-		base = unsafe.Pointer(s.Data)
+		base = s.Data
 		cap = s.Cap
 
 	case String:
@@ -1710,7 +1710,7 @@ func (v Value) Uint() uint64 {
 	case Uint32:
 		return uint64(*(*uint32)(p))
 	case Uint64:
-		return uint64(*(*uint64)(p))
+		return *(*uint64)(p)
 	case Uintptr:
 		return uint64(*(*uintptr)(p))
 	}
@@ -2267,13 +2267,13 @@ func makeInt(f flag, bits uint64, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 1:
-		*(*uint8)(unsafe.Pointer(ptr)) = uint8(bits)
+		*(*uint8)(ptr) = uint8(bits)
 	case 2:
-		*(*uint16)(unsafe.Pointer(ptr)) = uint16(bits)
+		*(*uint16)(ptr) = uint16(bits)
 	case 4:
-		*(*uint32)(unsafe.Pointer(ptr)) = uint32(bits)
+		*(*uint32)(ptr) = uint32(bits)
 	case 8:
-		*(*uint64)(unsafe.Pointer(ptr)) = bits
+		*(*uint64)(ptr) = bits
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
@@ -2285,9 +2285,9 @@ func makeFloat(f flag, v float64, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 4:
-		*(*float32)(unsafe.Pointer(ptr)) = float32(v)
+		*(*float32)(ptr) = float32(v)
 	case 8:
-		*(*float64)(unsafe.Pointer(ptr)) = v
+		*(*float64)(ptr) = v
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
@@ -2299,9 +2299,9 @@ func makeComplex(f flag, v complex128, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 8:
-		*(*complex64)(unsafe.Pointer(ptr)) = complex64(v)
+		*(*complex64)(ptr) = complex64(v)
 	case 16:
-		*(*complex128)(unsafe.Pointer(ptr)) = v
+		*(*complex128)(ptr) = v
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
diff --git a/src/regexp/onepass.go b/src/regexp/onepass.go
index 5b82f9666e..4991954820 100644
--- a/src/regexp/onepass.go
+++ b/src/regexp/onepass.go
@@ -450,7 +450,7 @@ func makeOnePass(p *onePassProg) *onePassProg {
 	for !instQueue.empty() {
 		visitQueue.clear()
 		pc := instQueue.next()
-		if !check(uint32(pc), m) {
+		if !check(pc, m) {
 			p = notOnePass
 			break
 		}
diff --git a/src/strconv/extfloat.go b/src/strconv/extfloat.go
index 019b4eebdc..7033e96c39 100644
--- a/src/strconv/extfloat.go
+++ b/src/strconv/extfloat.go
@@ -311,9 +311,9 @@ func (f *extFloat) AssignDecimal(mantissa uint64, exp10 int, neg bool, trunc boo
 	var extrabits uint
 	if f.exp <= denormalExp {
 		// f.mant * 2^f.exp is smaller than 2^(flt.bias+1).
-		extrabits = uint(63 - flt.mantbits + 1 + uint(denormalExp-f.exp))
+		extrabits = 63 - flt.mantbits + 1 + uint(denormalExp-f.exp)
 	} else {
-		extrabits = uint(63 - flt.mantbits)
+		extrabits = 63 - flt.mantbits
 	}
 
 	halfway := uint64(1) << (extrabits - 1)
diff --git a/src/strings/reader.go b/src/strings/reader.go
index 737873c099..74eed4d574 100644
--- a/src/strings/reader.go
+++ b/src/strings/reader.go
@@ -113,7 +113,7 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	case 0:
 		abs = offset
 	case 1:
-		abs = int64(r.i) + offset
+		abs = r.i + offset
 	case 2:
 		abs = int64(len(r.s)) + offset
 	default:
diff --git a/src/sync/pool.go b/src/sync/pool.go
index 4fb1a1af9d..2acf505f3c 100644
--- a/src/sync/pool.go
+++ b/src/sync/pool.go
@@ -179,8 +179,8 @@ func (p *Pool) pinSlow() *poolLocal {
 	// If GOMAXPROCS changes between GCs, we re-allocate the array and lose the old one.
 	size := runtime.GOMAXPROCS(0)
 	local := make([]poolLocal, size)
-	atomic.StorePointer((*unsafe.Pointer)(&p.local), unsafe.Pointer(&local[0])) // store-release
-	atomic.StoreUintptr(&p.localSize, uintptr(size))                            // store-release
+	atomic.StorePointer(&p.local, unsafe.Pointer(&local[0])) // store-release
+	atomic.StoreUintptr(&p.localSize, uintptr(size))         // store-release
 	return &local[pid]
 }
 
diff --git a/src/time/time.go b/src/time/time.go
index 4b9a0db730..92d635eec5 100644
--- a/src/time/time.go
+++ b/src/time/time.go
@@ -606,7 +606,7 @@ func (d Duration) Hours() float64 {
 // Add returns the time t+d.
 func (t Time) Add(d Duration) Time {
 	t.sec += int64(d / 1e9)
-	nsec := int32(t.nsec) + int32(d%1e9)
+	nsec := t.nsec + int32(d%1e9)
 	if nsec >= 1e9 {
 		t.sec++
 		nsec -= 1e9
@@ -623,7 +623,7 @@ func (t Time) Add(d Duration) Time {
 // will be returned.
 // To compute t-d for a duration d, use t.Add(-d).
 func (t Time) Sub(u Time) Duration {
-	d := Duration(t.sec-u.sec)*Second + Duration(int32(t.nsec)-int32(u.nsec))
+	d := Duration(t.sec-u.sec)*Second + Duration(t.nsec-u.nsec)
 	// Check for overflow or underflow.
 	switch {
 	case u.Add(d).Equal(t):
@@ -1125,7 +1125,7 @@ func (t Time) Round(d Duration) Time {
 // but it's still here in case we change our minds.
 func div(t Time, d Duration) (qmod2 int, r Duration) {
 	neg := false
-	nsec := int32(t.nsec)
+	nsec := t.nsec
 	if t.sec < 0 {
 		// Operate on absolute value.
 		neg = true
@@ -1159,7 +1159,7 @@ func div(t Time, d Duration) (qmod2 int, r Duration) {
 		tmp := (sec >> 32) * 1e9
 		u1 := tmp >> 32
 		u0 := tmp << 32
-		tmp = uint64(sec&0xFFFFFFFF) * 1e9
+		tmp = (sec & 0xFFFFFFFF) * 1e9
 		u0x, u0 := u0, u0+tmp
 		if u0 < u0x {
 			u1++
diff --git a/src/time/zoneinfo_windows.go b/src/time/zoneinfo_windows.go
index bcb8ccd563..c753119d5d 100644
--- a/src/time/zoneinfo_windows.go
+++ b/src/time/zoneinfo_windows.go
@@ -83,7 +83,7 @@ func extractCAPS(desc string) string {
 	var short []rune
 	for _, c := range desc {
 		if 'A' <= c && c <= 'Z' {
-			short = append(short, rune(c))
+			short = append(short, c)
 		}
 	}
 	return string(short)
diff --git a/src/unicode/letter.go b/src/unicode/letter.go
index 8443ee51a2..ffa083eb57 100644
--- a/src/unicode/letter.go
+++ b/src/unicode/letter.go
@@ -217,7 +217,7 @@ func to(_case int, r rune, caseRange []CaseRange) rune {
 		m := lo + (hi-lo)/2
 		cr := caseRange[m]
 		if rune(cr.Lo) <= r && r <= rune(cr.Hi) {
-			delta := rune(cr.Delta[_case])
+			delta := cr.Delta[_case]
 			if delta > MaxRune {
 				// In an Upper-Lower sequence, which always starts with
 				// an UpperCase letter, the real deltas always look like: