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// 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 types
import (
"fmt"
"go/ast"
"go/token"
"go/version"
"internal/goversion"
"strings"
)
// A goVersion is a Go language version string of the form "go1.%d"
// where d is the minor version number. goVersion strings don't
// contain release numbers ("go1.20.1" is not a valid goVersion).
type goVersion string
// asGoVersion returns v as a goVersion (e.g., "go1.20.1" becomes "go1.20").
// If v is not a valid Go version, the result is the empty string.
func asGoVersion(v string) goVersion {
return goVersion(version.Lang(v))
}
// isValid reports whether v is a valid Go version.
func (v goVersion) isValid() bool {
return v != ""
}
// cmp returns -1, 0, or +1 depending on whether x < y, x == y, or x > y,
// interpreted as Go versions.
func (x goVersion) cmp(y goVersion) int {
return version.Compare(string(x), string(y))
}
var (
// Go versions that introduced language changes
go1_9 = asGoVersion("go1.9")
go1_13 = asGoVersion("go1.13")
go1_14 = asGoVersion("go1.14")
go1_17 = asGoVersion("go1.17")
go1_18 = asGoVersion("go1.18")
go1_20 = asGoVersion("go1.20")
go1_21 = asGoVersion("go1.21")
go1_22 = asGoVersion("go1.22")
// current (deployed) Go version
go_current = asGoVersion(fmt.Sprintf("go1.%d", goversion.Version))
)
// langCompat reports an error if the representation of a numeric
// literal is not compatible with the current language version.
func (check *Checker) langCompat(lit *ast.BasicLit) {
s := lit.Value
if len(s) <= 2 || check.allowVersion(check.pkg, lit, go1_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 != token.INT && (radix == 'x' || radix == 'X') {
check.versionErrorf(lit, go1_13, "hexadecimal floating-point literals")
}
}
// allowVersion reports whether the given package is allowed to use version v.
func (check *Checker) allowVersion(pkg *Package, at positioner, v goVersion) 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
}
// If no explicit file version is specified,
// fileVersion corresponds to the module version.
var fileVersion goVersion
if pos := at.Pos(); pos.IsValid() {
// We need version.Lang below because file versions
// can be (unaltered) Config.GoVersion strings that
// may contain dot-release information.
fileVersion = asGoVersion(check.versions[check.fileFor(pos)])
}
return !fileVersion.isValid() || fileVersion.cmp(v) >= 0
}
// verifyVersionf is like allowVersion but also accepts a format string and arguments
// which are used to report a version error if allowVersion returns false. It uses the
// current package.
func (check *Checker) verifyVersionf(at positioner, v goVersion, format string, args ...interface{}) bool {
if !check.allowVersion(check.pkg, at, v) {
check.versionErrorf(at, v, format, args...)
return false
}
return true
}
// TODO(gri) Consider a more direct (position-independent) mechanism
// to identify which file we're in so that version checks
// work correctly in the absence of correct position info.
// fileFor returns the *ast.File which contains the position pos.
// If there are no files, the result is nil.
// The position must be valid.
func (check *Checker) fileFor(pos token.Pos) *ast.File {
assert(pos.IsValid())
// Eval and CheckExpr tests may not have any source files.
if len(check.files) == 0 {
return nil
}
for _, file := range check.files {
if file.FileStart <= pos && pos < file.FileEnd {
return file
}
}
panic(check.sprintf("file not found for pos = %d (%s)", int(pos), check.fset.Position(pos)))
}
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