mirror of
https://github.com/golang/go
synced 2024-11-23 20:40:07 -07:00
ceb849dd97
This CL introduces compiler support for the new binary and octal integer
literals, hexadecimal floats, and digit separators for all number literals.
The new Go 2 number literal scanner accepts the following liberal format:
number = [ prefix ] digits [ "." digits ] [ exponent ] [ "i" ] .
prefix = "0" [ "b" |"B" | "o" | "O" | "x" | "X" ] .
digits = { digit | "_" } .
exponent = ( "e" | "E" | "p" | "P" ) [ "+" | "-" ] digits .
If the number starts with "0x" or "0X", digit is any hexadecimal digit;
otherwise, digit is any decimal digit. If the accepted number is not valid,
errors are reported accordingly.
See the new test cases in scanner_test.go for a selection of valid and
invalid numbers and the respective error messages.
R=Go1.13
Updates #12711.
Updates #19308.
Updates #28493.
Updates #29008.
Change-Id: Ic8febc7bd4dc5186b16a8c8897691e81125cf0ca
Reviewed-on: https://go-review.googlesource.com/c/157677
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
32 lines
775 B
Go
32 lines
775 B
Go
// errorcheck
|
|
|
|
// Copyright 2015 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Expects to see error messages on 'p' exponents
|
|
// for non-hexadecimal floats.
|
|
|
|
package main
|
|
|
|
import "fmt"
|
|
|
|
const (
|
|
x1 = 1.1 // float
|
|
x2 = 1e10 // float
|
|
x3 = 0x1e10 // integer (e is a hex digit)
|
|
)
|
|
|
|
const x4 = 0x1p10 // valid hexadecimal float
|
|
const x5 = 1p10 // ERROR "'p' exponent requires hexadecimal mantissa"
|
|
const x6 = 0P0 // ERROR "'P' exponent requires hexadecimal mantissa"
|
|
|
|
func main() {
|
|
fmt.Printf("%g %T\n", x1, x1)
|
|
fmt.Printf("%g %T\n", x2, x2)
|
|
fmt.Printf("%g %T\n", x3, x3)
|
|
fmt.Printf("%g %T\n", x4, x4)
|
|
fmt.Printf("%g %T\n", x5, x5)
|
|
fmt.Printf("%g %T\n", x6, x6)
|
|
}
|