exp/sql: simplify some string conversions.

R=bradfitz
CC=golang-dev
https://golang.org/cl/5451112

src/pkg/exp/sql/convert.go

@@ -95,35 +95,26 @@ func convertAssign(dest, src interface{}) error {
 	switch dv.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		s := asString(src)
-		i64, err := strconv.ParseInt(s, 10, 64)
+		i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
-		if dv.OverflowInt(i64) {
-			return fmt.Errorf("string %q overflows %s", s, dv.Kind())
-		}
 		dv.SetInt(i64)
 		return nil
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		s := asString(src)
-		u64, err := strconv.ParseUint(s, 10, 64)
+		u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
-		if dv.OverflowUint(u64) {
-			return fmt.Errorf("string %q overflows %s", s, dv.Kind())
-		}
 		dv.SetUint(u64)
 		return nil
 	case reflect.Float32, reflect.Float64:
 		s := asString(src)
-		f64, err := strconv.ParseFloat(s, 64)
+		f64, err := strconv.ParseFloat(s, dv.Type().Bits())
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
-		if dv.OverflowFloat(f64) {
-			return fmt.Errorf("value %q overflows %s", s, dv.Kind())
-		}
 		dv.SetFloat(f64)
 		return nil
 	}

src/pkg/exp/sql/convert_test.go

@@ -55,7 +55,7 @@ var conversionTests = []conversionTest{
 
 	// Strings to integers
 	{s: "255", d: &scanuint8, wantuint: 255},
-	{s: "256", d: &scanuint8, wanterr: `string "256" overflows uint8`},
+	{s: "256", d: &scanuint8, wanterr: `converting string "256" to a uint8: 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`},