go version 源码
golang version 代码
文件路径：/src/cmd/compile/internal/types2/version.go
// Copyright 2021 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.
package types2
import (
"cmd/compile/internal/syntax"
"fmt"
"regexp"
"strconv"
"strings"
)
// langCompat reports an error if the representation of a numeric
// literal is not compatible with the current language version.
func (check *Checker) langCompat(lit *syntax.BasicLit) {
s := lit.Value
if len(s) <= 2 || check.allowVersion(check.pkg, 1, 13) {
return
}
// len(s) > 2
if strings.Contains(s, "_") {
check.versionErrorf(lit, "go1.13", "underscores in numeric literals")
return
}
if s[0] != '0' {
return
}
radix := s[1]
if radix == 'b' || radix == 'B' {
check.versionErrorf(lit, "go1.13", "binary literals")
return
}
if radix == 'o' || radix == 'O' {
check.versionErrorf(lit, "go1.13", "0o/0O-style octal literals")
return
}
if lit.Kind != syntax.IntLit && (radix == 'x' || radix == 'X') {
check.versionErrorf(lit, "go1.13", "hexadecimal floating-point literals")
}
}
// allowVersion reports whether the given package
// is allowed to use version major.minor.
func (check *Checker) allowVersion(pkg *Package, major, minor int) bool {
// We assume that imported packages have all been checked,
// so we only have to check for the local package.
if pkg != check.pkg {
return true
}
ma, mi := check.version.major, check.version.minor
return ma == 0 && mi == 0 || ma > major || ma == major && mi >= minor
}
type version struct {
major, minor int
}
// parseGoVersion parses a Go version string (such as "go1.12")
// and returns the version, or an error. If s is the empty
// string, the version is 0.0.
func parseGoVersion(s string) (v version, err error) {
if s == "" {
return
}
matches := goVersionRx.FindStringSubmatch(s)
if matches == nil {
err = fmt.Errorf(`should be something like "go1.12"`)
return
}
v.major, err = strconv.Atoi(matches[1])
if err != nil {
return
}
v.minor, err = strconv.Atoi(matches[2])
return
}
// goVersionRx matches a Go version string, e.g. "go1.12".
var goVersionRx = regexp.MustCompile(`^go([1-9][0-9]*)\.(0|[1-9][0-9]*)$`)
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