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// Copyright 2009 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 types
import (
"fmt"
"internal/goversion"
"log"
"regexp"
"strconv"
"cmd/compile/internal/base"
)
// A lang is a language version broken into major and minor numbers.
type lang struct {
major, minor int
}
// langWant is the desired language version set by the -lang flag.
// If the -lang flag is not set, this is the zero value, meaning that
// any language version is supported.
var langWant lang
// AllowsGoVersion reports whether a particular package
// is allowed to use Go version major.minor.
// We assume the imported packages have all been checked,
// so we only have to check the local package against the -lang flag.
func AllowsGoVersion(pkg *Pkg, major, minor int) bool {
if pkg == nil {
// TODO(mdempsky): Set Pkg for local types earlier.
pkg = LocalPkg
}
if pkg != LocalPkg {
// Assume imported packages passed type-checking.
return true
}
if langWant.major == 0 && langWant.minor == 0 {
return true
}
return langWant.major > major || (langWant.major == major && langWant.minor >= minor)
}
// ParseLangFlag verifies that the -lang flag holds a valid value, and
// exits if not. It initializes data used by langSupported.
func ParseLangFlag() {
if base.Flag.Lang == "" {
return
}
var err error
langWant, err = parseLang(base.Flag.Lang)
if err != nil {
log.Fatalf("invalid value %q for -lang: %v", base.Flag.Lang, err)
}
if def := currentLang(); base.Flag.Lang != def {
defVers, err := parseLang(def)
if err != nil {
log.Fatalf("internal error parsing default lang %q: %v", def, err)
}
if langWant.major > defVers.major || (langWant.major == defVers.major && langWant.minor > defVers.minor) {
log.Fatalf("invalid value %q for -lang: max known version is %q", base.Flag.Lang, def)
}
}
}
// parseLang parses a -lang option into a langVer.
func parseLang(s string) (lang, error) {
matches := goVersionRE.FindStringSubmatch(s)
if matches == nil {
return lang{}, fmt.Errorf(`should be something like "go1.12"`)
}
major, err := strconv.Atoi(matches[1])
if err != nil {
return lang{}, err
}
minor, err := strconv.Atoi(matches[2])
if err != nil {
return lang{}, err
}
return lang{major: major, minor: minor}, nil
}
// currentLang returns the current language version.
func currentLang() string {
return fmt.Sprintf("go1.%d", goversion.Version)
}
// goVersionRE is a regular expression that matches the valid
// arguments to the -lang flag.
var goVersionRE = regexp.MustCompile(`^go([1-9][0-9]*)\.(0|[1-9][0-9]*)$`)
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