fmt.Printf: fix bug in handling of %#v.

nice side effect: slices now obey their format verb. example:
	fmt.Printf("%q\n", []string{"a"})

R=rsc
CC=golang-dev
https://golang.org/cl/1729045

3 files changed, 68 insertions, 63 deletions

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index e48e874b15..7e59d4073e 100644
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -289,6 +289,14 @@ var fmttests = []fmtTest{
 	fmtTest{"%#v", make(chan int), "(chan int)(PTR)"},
 	fmtTest{"%#v", uint64(1<<64 - 1), "0xffffffffffffffff"},
 	fmtTest{"%#v", 1000000000, "1000000000"},
+	fmtTest{"%#v", map[string]int{"a": 1, "b": 2}, `map[string] int{"a":1, "b":2}`},
+	fmtTest{"%#v", map[string]B{"a": B{1, 2}, "b": B{3, 4}}, `map[string] fmt_test.B{"a":fmt_test.B{i:1, j:2}, "b":fmt_test.B{i:3, j:4}}`},
+	fmtTest{"%#v", []string{"a", "b"}, `[]string{"a", "b"}`},
+
+	// slices with other formats
+	fmtTest{"%#x", []int{1, 2, 15}, `[0x1 0x2 0xf]`},
+	fmtTest{"%x", []int{1, 2, 15}, `[1 2 f]`},
+	fmtTest{"%q", []string{"a", "b"}, `["a" "b"]`},
 
 	// renamings
 	fmtTest{"%v", renamedBool(true), "true"},
diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index 62fc9ff1c7..3ec1cf1394 100644
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -43,14 +43,13 @@ type fmt struct {
 	wid  int
 	prec int
 	// flags
-	widPresent    bool
-	precPresent   bool
-	minus         bool
-	plus          bool
-	sharp         bool
-	space         bool
-	zero          bool
-	preserveFlags bool // don't clear flags after this print; used to carry over in complex prints
+	widPresent  bool
+	precPresent bool
+	minus       bool
+	plus        bool
+	sharp       bool
+	space       bool
+	zero        bool
 }
 
 func (f *fmt) clearflags() {
@@ -120,9 +119,6 @@ func (f *fmt) pad(b []byte) {
 	if right > 0 {
 		f.writePadding(right, padding)
 	}
-	if !f.preserveFlags {
-		f.clearflags()
-	}
 }
 
 // append s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
@@ -140,9 +136,6 @@ func (f *fmt) padString(s string) {
 	if right > 0 {
 		f.writePadding(right, padding)
 	}
-	if !f.preserveFlags {
-		f.clearflags()
-	}
 }
 
 func putint(buf []byte, base, val uint64, digits string) int {
@@ -345,7 +338,6 @@ func (f *fmt) fmt_fb32(v float32) { f.padString(strconv.Ftoa32(v, 'b', 0)) }
 func (f *fmt) fmt_c64(v complex64, verb int) {
 	f.buf.WriteByte('(')
 	r := real(v)
-	f.preserveFlags = true
 	for i := 0; ; i++ {
 		switch verb {
 		case 'e':
@@ -359,7 +351,6 @@ func (f *fmt) fmt_c64(v complex64, verb int) {
 		case 'G':
 			f.fmt_G32(r)
 		}
-		f.preserveFlags = false
 		if i != 0 {
 			break
 		}
@@ -373,7 +364,6 @@ func (f *fmt) fmt_c64(v complex64, verb int) {
 func (f *fmt) fmt_c128(v complex128, verb int) {
 	f.buf.WriteByte('(')
 	r := real(v)
-	f.preserveFlags = true
 	for i := 0; ; i++ {
 		switch verb {
 		case 'e':
@@ -387,7 +377,6 @@ func (f *fmt) fmt_c128(v complex128, verb int) {
 		case 'G':
 			f.fmt_G64(r)
 		}
-		f.preserveFlags = false
 		if i != 0 {
 			break
 		}
diff --git a/src/pkg/fmt/print.go b/src/pkg/fmt/print.go
index bb2f08ea7b..20bfa9107f 100644
--- a/src/pkg/fmt/print.go
+++ b/src/pkg/fmt/print.go
@@ -443,7 +443,7 @@ func (p *pp) fmt0x64(v uint64) {
 	p.fmt.sharp = sharp
 }
 
-func (p *pp) fmtUint64(v uint64, verb int, sharp bool, value interface{}) {
+func (p *pp) fmtUint64(v uint64, verb int, goSyntax bool, value interface{}) {
 	switch verb {
 	case 'b':
 		p.fmt.integer(int64(v), 2, unsigned, ldigits)
@@ -452,7 +452,7 @@ func (p *pp) fmtUint64(v uint64, verb int, sharp bool, value interface{}) {
 	case 'd':
 		p.fmt.integer(int64(v), 10, unsigned, ldigits)
 	case 'v':
-		if sharp {
+		if goSyntax {
 			p.fmt0x64(v)
 		} else {
 			p.fmt.integer(int64(v), 10, unsigned, ldigits)
@@ -528,10 +528,10 @@ func (p *pp) fmtComplex128(v complex128, verb int, value interface{}) {
 	}
 }
 
-func (p *pp) fmtString(v string, verb int, sharp bool, value interface{}) {
+func (p *pp) fmtString(v string, verb int, goSyntax bool, value interface{}) {
 	switch verb {
 	case 'v':
-		if sharp {
+		if goSyntax {
 			p.fmt.fmt_q(v)
 		} else {
 			p.fmt.fmt_s(v)
@@ -549,24 +549,24 @@ func (p *pp) fmtString(v string, verb int, sharp bool, value interface{}) {
 	}
 }
 
-func (p *pp) fmtBytes(v []byte, verb int, sharp bool, depth int, value interface{}) {
+func (p *pp) fmtBytes(v []byte, verb int, goSyntax bool, depth int, value interface{}) {
 	if verb == 'v' {
-		if p.fmt.sharp {
+		if goSyntax {
 			p.buf.Write(bytesBytes)
 		} else {
 			p.buf.WriteByte('[')
 		}
 		for i, c := range v {
 			if i > 0 {
-				if p.fmt.sharp {
+				if goSyntax {
 					p.buf.Write(commaSpaceBytes)
 				} else {
 					p.buf.WriteByte(' ')
 				}
 			}
-			p.printField(c, 'v', p.fmt.plus, p.fmt.sharp, depth+1)
+			p.printField(c, 'v', p.fmt.plus, goSyntax, depth+1)
 		}
-		if sharp {
+		if goSyntax {
 			p.buf.WriteByte('}')
 		} else {
 			p.buf.WriteByte(']')
@@ -618,17 +618,17 @@ var (
 	uintptrBits = reflect.Typeof(uintptr(0)).Bits()
 )
 
-func (p *pp) printField(field interface{}, verb int, plus, sharp bool, depth int) (was_string bool) {
+func (p *pp) printField(field interface{}, verb int, plus, goSyntax bool, depth int) (was_string bool) {
 	if field != nil {
 		switch {
 		default:
 			if stringer, ok := field.(Stringer); ok {
-				p.printField(stringer.String(), verb, plus, sharp, depth)
+				p.printField(stringer.String(), verb, plus, goSyntax, depth)
 				return false // this value is not a string
 			}
-		case sharp:
+		case goSyntax:
 			if stringer, ok := field.(GoStringer); ok {
-				p.printField(stringer.GoString(), verb, plus, sharp, depth)
+				p.printField(stringer.GoString(), verb, plus, goSyntax, depth)
 				return false // this value is not a string
 			}
 		}
@@ -681,28 +681,28 @@ func (p *pp) printField(field interface{}, verb int, plus, sharp bool, depth int
 		p.fmtInt64(f, verb, field)
 		return false
 	case uint:
-		p.fmtUint64(uint64(f), verb, sharp, field)
+		p.fmtUint64(uint64(f), verb, goSyntax, field)
 		return false
 	case uint8:
-		p.fmtUint64(uint64(f), verb, sharp, field)
+		p.fmtUint64(uint64(f), verb, goSyntax, field)
 		return false
 	case uint16:
-		p.fmtUint64(uint64(f), verb, sharp, field)
+		p.fmtUint64(uint64(f), verb, goSyntax, field)
 		return false
 	case uint32:
-		p.fmtUint64(uint64(f), verb, sharp, field)
+		p.fmtUint64(uint64(f), verb, goSyntax, field)
 		return false
 	case uint64:
-		p.fmtUint64(f, verb, sharp, field)
+		p.fmtUint64(f, verb, goSyntax, field)
 		return false
 	case uintptr:
-		p.fmtUint64(uint64(f), verb, sharp, field)
+		p.fmtUint64(uint64(f), verb, goSyntax, field)
 		return false
 	case string:
-		p.fmtString(f, verb, sharp, field)
+		p.fmtString(f, verb, goSyntax, field)
 		return verb == 's' || verb == 'v'
 	case []byte:
-		p.fmtBytes(f, verb, sharp, depth, field)
+		p.fmtBytes(f, verb, goSyntax, depth, field)
 		return verb == 's'
 	}
 
@@ -718,7 +718,7 @@ func (p *pp) printField(field interface{}, verb int, plus, sharp bool, depth int
 	value := reflect.NewValue(field)
 	// Need to use reflection
 	// Special case for reflection values that know how to print with %p.
-	if verb == 'p' && p.fmtUintptrGetter(field, value, verb, sharp) {
+	if verb == 'p' && p.fmtUintptrGetter(field, value, verb, goSyntax) { // TODO: is this goSyntax right?
 		return false
 	}
 
@@ -729,7 +729,7 @@ BigSwitch:
 	case *reflect.IntValue:
 		p.fmtInt64(f.Get(), verb, field)
 	case *reflect.UintValue:
-		p.fmtUint64(uint64(f.Get()), verb, sharp, field)
+		p.fmtUint64(uint64(f.Get()), verb, goSyntax, field)
 	case *reflect.FloatValue:
 		if f.Type().Size() == 4 {
 			p.fmtFloat32(float32(f.Get()), verb, field)
@@ -743,9 +743,9 @@ BigSwitch:
 			p.fmtComplex128(complex128(f.Get()), verb, field)
 		}
 	case *reflect.StringValue:
-		p.fmtString(f.Get(), verb, sharp, field)
+		p.fmtString(f.Get(), verb, goSyntax, field)
 	case *reflect.MapValue:
-		if sharp {
+		if goSyntax {
 			p.buf.WriteString(f.Type().String())
 			p.buf.WriteByte('{')
 		} else {
@@ -754,60 +754,59 @@ BigSwitch:
 		keys := f.Keys()
 		for i, key := range keys {
 			if i > 0 {
-				if sharp {
+				if goSyntax {
 					p.buf.Write(commaSpaceBytes)
 				} else {
 					p.buf.WriteByte(' ')
 				}
 			}
-			p.printField(key.Interface(), verb, plus, sharp, depth+1)
+			p.printField(key.Interface(), verb, plus, goSyntax, depth+1)
 			p.buf.WriteByte(':')
-			p.printField(f.Elem(key).Interface(), verb, plus, sharp, depth+1)
+			p.printField(f.Elem(key).Interface(), verb, plus, goSyntax, depth+1)
 		}
-		if sharp {
+		if goSyntax {
 			p.buf.WriteByte('}')
 		} else {
 			p.buf.WriteByte(']')
 		}
 	case *reflect.StructValue:
-		if sharp {
+		if goSyntax {
 			p.buf.WriteString(reflect.Typeof(field).String())
 		}
 		p.add('{')
 		v := f
 		t := v.Type().(*reflect.StructType)
-		p.fmt.clearflags() // clear flags for p.printField
 		for i := 0; i < v.NumField(); i++ {
 			if i > 0 {
-				if sharp {
+				if goSyntax {
 					p.buf.Write(commaSpaceBytes)
 				} else {
 					p.buf.WriteByte(' ')
 				}
 			}
-			if plus || sharp {
+			if plus || goSyntax {
 				if f := t.Field(i); f.Name != "" {
 					p.buf.WriteString(f.Name)
 					p.buf.WriteByte(':')
 				}
 			}
-			p.printField(getField(v, i).Interface(), verb, plus, sharp, depth+1)
+			p.printField(getField(v, i).Interface(), verb, plus, goSyntax, depth+1)
 		}
 		p.buf.WriteByte('}')
 	case *reflect.InterfaceValue:
 		value := f.Elem()
 		if value == nil {
-			if sharp {
+			if goSyntax {
 				p.buf.WriteString(reflect.Typeof(field).String())
 				p.buf.Write(nilParenBytes)
 			} else {
 				p.buf.Write(nilAngleBytes)
 			}
 		} else {
-			return p.printField(value.Interface(), verb, plus, sharp, depth+1)
+			return p.printField(value.Interface(), verb, plus, goSyntax, depth+1)
 		}
 	case reflect.ArrayOrSliceValue:
-		if sharp {
+		if goSyntax {
 			p.buf.WriteString(reflect.Typeof(field).String())
 			p.buf.WriteByte('{')
 		} else {
@@ -815,15 +814,15 @@ BigSwitch:
 		}
 		for i := 0; i < f.Len(); i++ {
 			if i > 0 {
-				if sharp {
+				if goSyntax {
 					p.buf.Write(commaSpaceBytes)
 				} else {
 					p.buf.WriteByte(' ')
 				}
 			}
-			p.printField(f.Elem(i).Interface(), verb, plus, sharp, depth+1)
+			p.printField(f.Elem(i).Interface(), verb, plus, goSyntax, depth+1)
 		}
-		if sharp {
+		if goSyntax {
 			p.buf.WriteByte('}')
 		} else {
 			p.buf.WriteByte(']')
@@ -836,15 +835,15 @@ BigSwitch:
 			switch a := f.Elem().(type) {
 			case reflect.ArrayOrSliceValue:
 				p.buf.WriteByte('&')
-				p.printField(a.Interface(), verb, plus, sharp, depth+1)
+				p.printField(a.Interface(), verb, plus, goSyntax, depth+1)
 				break BigSwitch
 			case *reflect.StructValue:
 				p.buf.WriteByte('&')
-				p.printField(a.Interface(), verb, plus, sharp, depth+1)
+				p.printField(a.Interface(), verb, plus, goSyntax, depth+1)
 				break BigSwitch
 			}
 		}
-		if sharp {
+		if goSyntax {
 			p.buf.WriteByte('(')
 			p.buf.WriteString(reflect.Typeof(field).String())
 			p.buf.WriteByte(')')
@@ -863,7 +862,7 @@ BigSwitch:
 		}
 		p.fmt0x64(uint64(v))
 	case uintptrGetter:
-		if p.fmtUintptrGetter(field, value, verb, sharp) {
+		if p.fmtUintptrGetter(field, value, verb, goSyntax) {
 			break
 		}
 		p.unknownType(f)
@@ -948,7 +947,15 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 			}
 		}
 
-		p.printField(field, c, p.fmt.plus, p.fmt.sharp, 0)
+		goSyntax := c == 'v' && p.fmt.sharp
+		if goSyntax {
+			p.fmt.sharp = false
+		}
+		plus := c == 'v' && p.fmt.plus
+		if plus {
+			p.fmt.plus = false
+		}
+		p.printField(field, c, plus, goSyntax, 0)
 	}
 
 	if fieldnum < len(a) {
@@ -971,6 +978,7 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 func (p *pp) doPrint(a []interface{}, addspace, addnewline bool) {
 	prev_string := false
 	for fieldnum := 0; fieldnum < len(a); fieldnum++ {
+		p.fmt.clearflags()
 		// always add spaces if we're doing println
 		field := a[fieldnum]
 		if fieldnum > 0 {