strconv: include package and function name in error strings

Fixes #2548.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5484062

src/pkg/exp/sql/convert_test.go

@@ -55,10 +55,10 @@ var conversionTests = []conversionTest{
 
 	// Strings to integers
 	{s: "255", d: &scanuint8, wantuint: 255},
-	{s: "256", d: &scanuint8, wanterr: `converting string "256" to a uint8: parsing "256": value out of range`},
+	{s: "256", d: &scanuint8, wanterr: `converting string "256" to a uint8: strconv.ParseUint: parsing "256": value out of range`},
 	{s: "256", d: &scanuint16, wantuint: 256},
 	{s: "-1", d: &scanint, wantint: -1},
-	{s: "foo", d: &scanint, wanterr: `converting string "foo" to a int: parsing "foo": invalid syntax`},
+	{s: "foo", d: &scanint, wanterr: `converting string "foo" to a int: strconv.ParseInt: parsing "foo": invalid syntax`},
 
 	// True bools
 	{s: true, d: &scanbool, wantbool: true},

src/pkg/strconv/atob.go

@@ -14,7 +14,7 @@ func ParseBool(str string) (value bool, err error) {
 	case "0", "f", "F", "false", "FALSE", "False":
 		return false, nil
 	}
-	return false, &NumError{str, ErrSyntax}
+	return false, syntaxError("ParseBool", str)
 }
 
 // FormatBool returns "true" or "false" according to the value of b

src/pkg/strconv/atof.go

@@ -338,6 +338,8 @@ func (d *decimal) atof32() (f float32, ok bool) {
 	return
 }
 
+const fnParseFloat = "ParseFloat"
+
 func atof32(s string) (f float32, err error) {
 	if val, ok := special(s); ok {
 		return float32(val), nil
@@ -345,7 +347,7 @@ func atof32(s string) (f float32, err error) {
 
 	var d decimal
 	if !d.set(s) {
-		return 0, &NumError{s, ErrSyntax}
+		return 0, syntaxError(fnParseFloat, s)
 	}
 	if optimize {
 		if f, ok := d.atof32(); ok {
@@ -355,7 +357,7 @@ func atof32(s string) (f float32, err error) {
 	b, ovf := d.floatBits(&float32info)
 	f = math.Float32frombits(uint32(b))
 	if ovf {
-		err = &NumError{s, ErrRange}
+		err = rangeError(fnParseFloat, s)
 	}
 	return f, err
 }
@@ -367,7 +369,7 @@ func atof64(s string) (f float64, err error) {
 
 	var d decimal
 	if !d.set(s) {
-		return 0, &NumError{s, ErrSyntax}
+		return 0, syntaxError(fnParseFloat, s)
 	}
 	if optimize {
 		if f, ok := d.atof64(); ok {
@@ -377,7 +379,7 @@ func atof64(s string) (f float64, err error) {
 	b, ovf := d.floatBits(&float64info)
 	f = math.Float64frombits(b)
 	if ovf {
-		err = &NumError{s, ErrRange}
+		err = rangeError(fnParseFloat, s)
 	}
 	return f, err
 }

src/pkg/strconv/atof_test.go

@@ -119,7 +119,7 @@ func init() {
 	for i := range atoftests {
 		test := &atoftests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseFloat", test.in, test.err}
 		}
 	}
 }

src/pkg/strconv/atoi.go

@@ -14,11 +14,22 @@ var ErrSyntax = errors.New("invalid syntax")
 
 // A NumError records a failed conversion.
 type NumError struct {
-	Num string // the input
-	Err error  // the reason the conversion failed (ErrRange, ErrSyntax)
+	Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
+	Num  string // the input
+	Err  error  // the reason the conversion failed (ErrRange, ErrSyntax)
 }
 
-func (e *NumError) Error() string { return `parsing "` + e.Num + `": ` + e.Err.Error() }
+func (e *NumError) Error() string {
+	return "strconv." + e.Func + ": " + `parsing "` + e.Num + `": ` + e.Err.Error()
+}
+
+func syntaxError(fn, str string) *NumError {
+	return &NumError{fn, str, ErrSyntax}
+}
+
+func rangeError(fn, str string) *NumError {
+	return &NumError{fn, str, ErrRange}
+}
 
 const intSize = 32 << uint(^uint(0)>>63)
 
@@ -116,7 +127,7 @@ func ParseUint(s string, b int, bitSize int) (n uint64, err error) {
 	return n, nil
 
 Error:
-	return n, &NumError{s0, err}
+	return n, &NumError{"ParseUint", s0, err}
 }
 
 // ParseInt interprets a string s in the given base (2 to 36) and
@@ -134,13 +145,15 @@ Error:
 // to s cannot be represented by a signed integer of the
 // given size, err.Error = ErrRange.
 func ParseInt(s string, base int, bitSize int) (i int64, err error) {
+	const fnParseInt = "ParseInt"
+
 	if bitSize == 0 {
 		bitSize = int(IntSize)
 	}
 
 	// Empty string bad.
 	if len(s) == 0 {
-		return 0, &NumError{s, ErrSyntax}
+		return 0, syntaxError(fnParseInt, s)
 	}
 
 	// Pick off leading sign.
@@ -157,15 +170,16 @@ func ParseInt(s string, base int, bitSize int) (i int64, err error) {
 	var un uint64
 	un, err = ParseUint(s, base, bitSize)
 	if err != nil && err.(*NumError).Err != ErrRange {
+		err.(*NumError).Func = fnParseInt
 		err.(*NumError).Num = s0
 		return 0, err
 	}
 	cutoff := uint64(1 << uint(bitSize-1))
 	if !neg && un >= cutoff {
-		return int64(cutoff - 1), &NumError{s0, ErrRange}
+		return int64(cutoff - 1), rangeError(fnParseInt, s0)
 	}
 	if neg && un > cutoff {
-		return -int64(cutoff), &NumError{s0, ErrRange}
+		return -int64(cutoff), rangeError(fnParseInt, s0)
 	}
 	n := int64(un)
 	if neg {

src/pkg/strconv/atoi_test.go

@@ -152,37 +152,37 @@ func init() {
 	for i := range atoui64tests {
 		test := &atoui64tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseUint", test.in, test.err}
 		}
 	}
 	for i := range btoui64tests {
 		test := &btoui64tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseUint", test.in, test.err}
 		}
 	}
 	for i := range atoi64tests {
 		test := &atoi64tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseInt", test.in, test.err}
 		}
 	}
 	for i := range btoi64tests {
 		test := &btoi64tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseInt", test.in, test.err}
 		}
 	}
 	for i := range atoui32tests {
 		test := &atoui32tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseUint", test.in, test.err}
 		}
 	}
 	for i := range atoi32tests {
 		test := &atoi32tests[i]
 		if test.err != nil {
-			test.err = &NumError{test.in, test.err}
+			test.err = &NumError{"ParseInt", test.in, test.err}
 		}
 	}
 }