"go/ast"
"go/constant"
"go/token"
+ "internal/godebug"
+ "internal/goversion"
+ . "internal/types/errors"
)
+// nopos indicates an unknown position
+var nopos token.Pos
+
// debugging/development support
-const (
- debug = false // leave on during development
- trace = false // turn on for detailed type resolution traces
-)
+const debug = false // leave on during development
-// If forceStrict is set, the type-checker enforces additional
-// rules not specified by the Go 1 spec, but which will
-// catch guaranteed run-time errors if the respective
-// code is executed. In other words, programs passing in
-// strict mode are Go 1 compliant, but not all Go 1 programs
-// will pass in strict mode. The additional rules are:
-//
-// - A type assertion x.(T) where T is an interface type
-// is invalid if any (statically known) method that exists
-// for both x and T have different signatures.
-//
-const forceStrict = false
+// gotypesalias controls the use of Alias types
+var gotypesalias = godebug.New("gotypesalias")
// exprInfo stores information about an untyped expression.
type exprInfo struct {
val constant.Value // constant value; or nil (if not a constant)
}
-// A context represents the context within which an object is type-checked.
-type context struct {
+// An environment represents the environment within which an object is
+// type-checked.
+type environment struct {
decl *declInfo // package-level declaration whose init expression/function body is checked
scope *Scope // top-most scope for lookups
pos token.Pos // if valid, identifiers are looked up as if at position pos (used by Eval)
iota constant.Value // value of iota in a constant declaration; nil otherwise
errpos positioner // if set, identifier position of a constant with inherited initializer
+ inTParamList bool // set if inside a type parameter list
sig *Signature // function signature if inside a function; nil otherwise
isPanic map[*ast.CallExpr]bool // set of panic call expressions (used for termination check)
hasLabel bool // set if a function makes use of labels (only ~1% of functions); unused outside functions
hasCallOrRecv bool // set if an expression contains a function call or channel receive operation
}
-// lookup looks up name in the current context and returns the matching object, or nil.
-func (ctxt *context) lookup(name string) Object {
- _, obj := ctxt.scope.LookupParent(name, ctxt.pos)
+// lookup looks up name in the current environment and returns the matching object, or nil.
+func (env *environment) lookup(name string) Object {
+ _, obj := env.scope.LookupParent(name, env.pos)
return obj
}
// If debug is set, describef sets a printf-formatted description for action a.
// Otherwise, it is a no-op.
-func (a *action) describef(pos positioner, format string, args ...interface{}) {
+func (a *action) describef(pos positioner, format string, args ...any) {
if debug {
a.desc = &actionDesc{pos, format, args}
}
type actionDesc struct {
pos positioner
format string
- args []interface{}
+ args []any
}
// A Checker maintains the state of the type checker.
-// It must be created with NewChecker.
+// It must be created with [NewChecker].
type Checker struct {
// package information
// (initialized by NewChecker, valid for the life-time of checker)
+
+ // If EnableAlias is set, alias declarations produce an Alias type.
+ // Otherwise the alias information is only in the type name, which
+ // points directly to the actual (aliased) type.
+ enableAlias bool
+
conf *Config
+ ctxt *Context // context for de-duplicating instances
fset *token.FileSet
pkg *Package
*Info
version version // accepted language version
+ posVers map[token.Pos]version // maps file start positions to versions (may be nil)
nextID uint64 // unique Id for type parameters (first valid Id is 1)
objMap map[Object]*declInfo // maps package-level objects and (non-interface) methods to declaration info
impMap map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
+ valids instanceLookup // valid *Named (incl. instantiated) types per the validType check
// pkgPathMap maps package names to the set of distinct import paths we've
// seen for that name, anywhere in the import graph. It is used for
imports []*PkgName // list of imported packages
dotImportMap map[dotImportKey]*PkgName // maps dot-imported objects to the package they were dot-imported through
recvTParamMap map[*ast.Ident]*TypeParam // maps blank receiver type parameters to their type
+ brokenAliases map[*TypeName]bool // set of aliases with broken (not yet determined) types
+ unionTypeSets map[*Union]*_TypeSet // computed type sets for union types
mono monoGraph // graph for detecting non-monomorphizable instantiation loops
firstErr error // first error encountered
untyped map[ast.Expr]exprInfo // map of expressions without final type
delayed []action // stack of delayed action segments; segments are processed in FIFO order
objPath []Object // path of object dependencies during type inference (for cycle reporting)
- defTypes []*Named // defined types created during type checking, for final validation.
+ cleaners []cleaner // list of types that may need a final cleanup at the end of type-checking
- // context within which the current object is type-checked
- // (valid only for the duration of type-checking a specific object)
- context
+ // environment within which the current object is type-checked (valid only
+ // for the duration of type-checking a specific object)
+ environment
// debugging
indent int // indentation for tracing
from.addDep(to)
}
+// Note: The following three alias-related functions are only used
+// when Alias types are not enabled.
+
+// brokenAlias records that alias doesn't have a determined type yet.
+// It also sets alias.typ to Typ[Invalid].
+// Not used if check.enableAlias is set.
+func (check *Checker) brokenAlias(alias *TypeName) {
+ assert(!check.enableAlias)
+ if check.brokenAliases == nil {
+ check.brokenAliases = make(map[*TypeName]bool)
+ }
+ check.brokenAliases[alias] = true
+ alias.typ = Typ[Invalid]
+}
+
+// validAlias records that alias has the valid type typ (possibly Typ[Invalid]).
+func (check *Checker) validAlias(alias *TypeName, typ Type) {
+ assert(!check.enableAlias)
+ delete(check.brokenAliases, alias)
+ alias.typ = typ
+}
+
+// isBrokenAlias reports whether alias doesn't have a determined type yet.
+func (check *Checker) isBrokenAlias(alias *TypeName) bool {
+ assert(!check.enableAlias)
+ return check.brokenAliases[alias]
+}
+
func (check *Checker) rememberUntyped(e ast.Expr, lhs bool, mode operandMode, typ *Basic, val constant.Value) {
m := check.untyped
if m == nil {
return obj
}
-// NewChecker returns a new Checker instance for a given package.
-// Package files may be added incrementally via checker.Files.
+type cleaner interface {
+ cleanup()
+}
+
+// needsCleanup records objects/types that implement the cleanup method
+// which will be called at the end of type-checking.
+func (check *Checker) needsCleanup(c cleaner) {
+ check.cleaners = append(check.cleaners, c)
+}
+
+// NewChecker returns a new [Checker] instance for a given package.
+// [Package] files may be added incrementally via checker.Files.
func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker {
// make sure we have a configuration
if conf == nil {
conf = new(Config)
}
- // make sure we have a context
- if conf.Context == nil {
- conf.Context = NewContext()
- }
-
// make sure we have an info struct
if info == nil {
info = new(Info)
}
- version, err := parseGoVersion(conf.GoVersion)
- if err != nil {
- panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
- }
+ // Note: clients may call NewChecker with the Unsafe package, which is
+ // globally shared and must not be mutated. Therefore NewChecker must not
+ // mutate *pkg.
+ //
+ // (previously, pkg.goVersion was mutated here: go.dev/issue/61212)
return &Checker{
- conf: conf,
- fset: fset,
- pkg: pkg,
- Info: info,
- version: version,
- objMap: make(map[Object]*declInfo),
- impMap: make(map[importKey]*Package),
+ enableAlias: gotypesalias.Value() == "1",
+ conf: conf,
+ ctxt: conf.Context,
+ fset: fset,
+ pkg: pkg,
+ Info: info,
+ objMap: make(map[Object]*declInfo),
+ impMap: make(map[importKey]*Package),
}
}
check.methods = nil
check.untyped = nil
check.delayed = nil
+ check.objPath = nil
+ check.cleaners = nil
// determine package name and collect valid files
pkg := check.pkg
if name != "_" {
pkg.name = name
} else {
- check.errorf(file.Name, _BlankPkgName, "invalid package name _")
+ check.error(file.Name, BlankPkgName, "invalid package name _")
}
fallthrough
check.files = append(check.files, file)
default:
- check.errorf(atPos(file.Package), _MismatchedPkgName, "package %s; expected %s", name, pkg.name)
+ check.errorf(atPos(file.Package), MismatchedPkgName, "package %s; expected %s", name, pkg.name)
// ignore this file
}
}
+
+ // collect file versions
+ for _, file := range check.files {
+ check.recordFileVersion(file, check.conf.GoVersion) // record package version (possibly zero version)
+ if v, _ := parseGoVersion(file.GoVersion); v.major > 0 {
+ if v.equal(check.version) {
+ continue
+ }
+ // Go 1.21 introduced the feature of setting the go.mod
+ // go line to an early version of Go and allowing //go:build lines
+ // to “upgrade” the Go version in a given file.
+ // We can do that backwards compatibly.
+ // Go 1.21 also introduced the feature of allowing //go:build lines
+ // to “downgrade” the Go version in a given file.
+ // That can't be done compatibly in general, since before the
+ // build lines were ignored and code got the module's Go version.
+ // To work around this, downgrades are only allowed when the
+ // module's Go version is Go 1.21 or later.
+ // If there is no check.version, then we don't really know what Go version to apply.
+ // Legacy tools may do this, and they historically have accepted everything.
+ // Preserve that behavior by ignoring //go:build constraints entirely in that case.
+ if (v.before(check.version) && check.version.before(go1_21)) || check.version.equal(go0_0) {
+ continue
+ }
+ if check.posVers == nil {
+ check.posVers = make(map[token.Pos]version)
+ }
+ check.posVers[file.FileStart] = v
+ check.recordFileVersion(file, file.GoVersion) // overwrite package version
+ }
+ }
}
// A bailout panic is used for early termination.
var errBadCgo = errors.New("cannot use FakeImportC and go115UsesCgo together")
func (check *Checker) checkFiles(files []*ast.File) (err error) {
+ if check.pkg == Unsafe {
+ // Defensive handling for Unsafe, which cannot be type checked, and must
+ // not be mutated. See https://go.dev/issue/61212 for an example of where
+ // Unsafe is passed to NewChecker.
+ return nil
+ }
+
+ // Note: parseGoVersion and the subsequent checks should happen once,
+ // when we create a new Checker, not for each batch of files.
+ // We can't change it at this point because NewChecker doesn't
+ // return an error.
+ check.version, err = parseGoVersion(check.conf.GoVersion)
+ if err != nil {
+ return err
+ }
+ if check.version.after(version{1, goversion.Version}) {
+ return fmt.Errorf("package requires newer Go version %v", check.version)
+ }
if check.conf.FakeImportC && check.conf.go115UsesCgo {
return errBadCgo
}
defer check.handleBailout(&err)
+ print := func(msg string) {
+ if check.conf._Trace {
+ fmt.Println()
+ fmt.Println(msg)
+ }
+ }
+
+ print("== initFiles ==")
check.initFiles(files)
+ print("== collectObjects ==")
check.collectObjects()
+ print("== packageObjects ==")
check.packageObjects()
+ print("== processDelayed ==")
check.processDelayed(0) // incl. all functions
- check.expandDefTypes()
+ print("== cleanup ==")
+ check.cleanup()
+ print("== initOrder ==")
check.initOrder()
if !check.conf.DisableUnusedImportCheck {
+ print("== unusedImports ==")
check.unusedImports()
}
+ print("== recordUntyped ==")
check.recordUntyped()
if check.firstErr == nil {
check.monomorph()
}
+ check.pkg.goVersion = check.conf.GoVersion
check.pkg.complete = true
// no longer needed - release memory
check.pkgPathMap = nil
check.seenPkgMap = nil
check.recvTParamMap = nil
- check.defTypes = nil
+ check.brokenAliases = nil
+ check.unionTypeSets = nil
+ check.ctxt = nil
// TODO(rFindley) There's more memory we should release at this point.
// this is a sufficiently bounded process.
for i := top; i < len(check.delayed); i++ {
a := &check.delayed[i]
- if trace && a.desc != nil {
- fmt.Println()
- check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+ if check.conf._Trace {
+ if a.desc != nil {
+ check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+ } else {
+ check.trace(nopos, "-- delayed %p", a.f)
+ }
}
a.f() // may append to check.delayed
+ if check.conf._Trace {
+ fmt.Println()
+ }
}
assert(top <= len(check.delayed)) // stack must not have shrunk
check.delayed = check.delayed[:top]
}
-func (check *Checker) expandDefTypes() {
- // Ensure that every defined type created in the course of type-checking has
- // either non-*Named underlying, or is unresolved.
- //
- // This guarantees that we don't leak any types whose underlying is *Named,
- // because any unresolved instances will lazily compute their underlying by
- // substituting in the underlying of their origin. The origin must have
- // either been imported or type-checked and expanded here, and in either case
- // its underlying will be fully expanded.
- for i := 0; i < len(check.defTypes); i++ {
- n := check.defTypes[i]
- switch n.underlying.(type) {
- case nil:
- if n.resolver == nil {
- panic("nil underlying")
- }
- case *Named:
- n.under() // n.under may add entries to check.defTypes
- }
- n.check = nil
+// cleanup runs cleanup for all collected cleaners.
+func (check *Checker) cleanup() {
+ // Don't use a range clause since Named.cleanup may add more cleaners.
+ for i := 0; i < len(check.cleaners); i++ {
+ check.cleaners[i].cleanup()
}
+ check.cleaners = nil
}
func (check *Checker) record(x *operand) {
assert(val != nil)
// We check allBasic(typ, IsConstType) here as constant expressions may be
// recorded as type parameters.
- assert(typ == Typ[Invalid] || allBasic(typ, IsConstType))
+ assert(!isValid(typ) || allBasic(typ, IsConstType))
}
if m := check.Types; m != nil {
m[x] = TypeAndValue{mode, typ, val}
}
}
-func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
+// recordCommaOkTypes updates recorded types to reflect that x is used in a commaOk context
+// (and therefore has tuple type).
+func (check *Checker) recordCommaOkTypes(x ast.Expr, a []*operand) {
assert(x != nil)
- if a[0] == nil || a[1] == nil {
+ assert(len(a) == 2)
+ if a[0].mode == invalid {
return
}
- assert(isTyped(a[0]) && isTyped(a[1]) && (isBoolean(a[1]) || a[1] == universeError))
+ t0, t1 := a[0].typ, a[1].typ
+ assert(isTyped(t0) && isTyped(t1) && (isBoolean(t1) || t1 == universeError))
if m := check.Types; m != nil {
for {
tv := m[x]
assert(tv.Type != nil) // should have been recorded already
pos := x.Pos()
tv.Type = NewTuple(
- NewVar(pos, check.pkg, "", a[0]),
- NewVar(pos, check.pkg, "", a[1]),
+ NewVar(pos, check.pkg, "", t0),
+ NewVar(pos, check.pkg, "", t1),
)
m[x] = tv
// if x is a parenthesized expression (p.X), update p.X
assert(ident != nil)
assert(typ != nil)
if m := check.Instances; m != nil {
- m[ident] = Instance{NewTypeList(targs), typ}
+ m[ident] = Instance{newTypeList(targs), typ}
}
}
m[node] = scope
}
}
+
+func (check *Checker) recordFileVersion(file *ast.File, version string) {
+ if m := check.FileVersions; m != nil {
+ m[file] = version
+ }
+}