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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.
// Derived from go/internal/gcimporter/ureader.go
//go:build go1.18
// +build go1.18
package gcimporter
import (
"go/token"
"go/types"
"strings"
"golang.org/x/tools/internal/pkgbits"
)
// A pkgReader holds the shared state for reading a unified IR package
// description.
type pkgReader struct {
pkgbits.PkgDecoder
fake fakeFileSet
ctxt *types.Context
imports map[string]*types.Package // previously imported packages, indexed by path
// lazily initialized arrays corresponding to the unified IR
// PosBase, Pkg, and Type sections, respectively.
posBases []string // position bases (i.e., file names)
pkgs []*types.Package
typs []types.Type
// laterFns holds functions that need to be invoked at the end of
// import reading.
laterFns []func()
// laterFors is used in case of 'type A B' to ensure that B is processed before A.
laterFors map[types.Type]int
// ifaces holds a list of constructed Interfaces, which need to have
// Complete called after importing is done.
ifaces []*types.Interface
}
// later adds a function to be invoked at the end of import reading.
func (pr *pkgReader) later(fn func()) {
pr.laterFns = append(pr.laterFns, fn)
}
// See cmd/compile/internal/noder.derivedInfo.
type derivedInfo struct {
idx pkgbits.Index
needed bool
}
// See cmd/compile/internal/noder.typeInfo.
type typeInfo struct {
idx pkgbits.Index
derived bool
}
func UImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
s := string(data)
s = s[:strings.LastIndex(s, "\n$$\n")]
input := pkgbits.NewPkgDecoder(path, s)
pkg = readUnifiedPackage(fset, nil, imports, input)
return
}
// laterFor adds a function to be invoked at the end of import reading, and records the type that function is finishing.
func (pr *pkgReader) laterFor(t types.Type, fn func()) {
if pr.laterFors == nil {
pr.laterFors = make(map[types.Type]int)
}
pr.laterFors[t] = len(pr.laterFns)
pr.laterFns = append(pr.laterFns, fn)
}
// readUnifiedPackage reads a package description from the given
// unified IR export data decoder.
func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
pr := pkgReader{
PkgDecoder: input,
fake: fakeFileSet{
fset: fset,
files: make(map[string]*fileInfo),
},
ctxt: ctxt,
imports: imports,
posBases: make([]string, input.NumElems(pkgbits.RelocPosBase)),
pkgs: make([]*types.Package, input.NumElems(pkgbits.RelocPkg)),
typs: make([]types.Type, input.NumElems(pkgbits.RelocType)),
}
defer pr.fake.setLines()
r := pr.newReader(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)
pkg := r.pkg()
r.Bool() // has init
for i, n := 0, r.Len(); i < n; i++ {
// As if r.obj(), but avoiding the Scope.Lookup call,
// to avoid eager loading of imports.
r.Sync(pkgbits.SyncObject)
assert(!r.Bool())
r.p.objIdx(r.Reloc(pkgbits.RelocObj))
assert(r.Len() == 0)
}
r.Sync(pkgbits.SyncEOF)
for _, fn := range pr.laterFns {
fn()
}
for _, iface := range pr.ifaces {
iface.Complete()
}
pkg.MarkComplete()
return pkg
}
// A reader holds the state for reading a single unified IR element
// within a package.
type reader struct {
pkgbits.Decoder
p *pkgReader
dict *readerDict
}
// A readerDict holds the state for type parameters that parameterize
// the current unified IR element.
type readerDict struct {
// bounds is a slice of typeInfos corresponding to the underlying
// bounds of the element's type parameters.
bounds []typeInfo
// tparams is a slice of the constructed TypeParams for the element.
tparams []*types.TypeParam
// devived is a slice of types derived from tparams, which may be
// instantiated while reading the current element.
derived []derivedInfo
derivedTypes []types.Type // lazily instantiated from derived
}
func (pr *pkgReader) newReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
return &reader{
Decoder: pr.NewDecoder(k, idx, marker),
p: pr,
}
}
func (pr *pkgReader) tempReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
return &reader{
Decoder: pr.TempDecoder(k, idx, marker),
p: pr,
}
}
func (pr *pkgReader) retireReader(r *reader) {
pr.RetireDecoder(&r.Decoder)
}
// @@@ Positions
func (r *reader) pos() token.Pos {
r.Sync(pkgbits.SyncPos)
if !r.Bool() {
return token.NoPos
}
// TODO(mdempsky): Delta encoding.
posBase := r.posBase()
line := r.Uint()
col := r.Uint()
return r.p.fake.pos(posBase, int(line), int(col))
}
func (r *reader) posBase() string {
return r.p.posBaseIdx(r.Reloc(pkgbits.RelocPosBase))
}
func (pr *pkgReader) posBaseIdx(idx pkgbits.Index) string {
if b := pr.posBases[idx]; b != "" {
return b
}
var filename string
{
r := pr.tempReader(pkgbits.RelocPosBase, idx, pkgbits.SyncPosBase)
// Within types2, position bases have a lot more details (e.g.,
// keeping track of where //line directives appeared exactly).
//
// For go/types, we just track the file name.
filename = r.String()
if r.Bool() { // file base
// Was: "b = token.NewTrimmedFileBase(filename, true)"
} else { // line base
pos := r.pos()
line := r.Uint()
col := r.Uint()
// Was: "b = token.NewLineBase(pos, filename, true, line, col)"
_, _, _ = pos, line, col
}
pr.retireReader(r)
}
b := filename
pr.posBases[idx] = b
return b
}
// @@@ Packages
func (r *reader) pkg() *types.Package {
r.Sync(pkgbits.SyncPkg)
return r.p.pkgIdx(r.Reloc(pkgbits.RelocPkg))
}
func (pr *pkgReader) pkgIdx(idx pkgbits.Index) *types.Package {
// TODO(mdempsky): Consider using some non-nil pointer to indicate
// the universe scope, so we don't need to keep re-reading it.
if pkg := pr.pkgs[idx]; pkg != nil {
return pkg
}
pkg := pr.newReader(pkgbits.RelocPkg, idx, pkgbits.SyncPkgDef).doPkg()
pr.pkgs[idx] = pkg
return pkg
}
func (r *reader) doPkg() *types.Package {
path := r.String()
switch path {
case "":
path = r.p.PkgPath()
case "builtin":
return nil // universe
case "unsafe":
return types.Unsafe
}
if pkg := r.p.imports[path]; pkg != nil {
return pkg
}
name := r.String()
pkg := types.NewPackage(path, name)
r.p.imports[path] = pkg
imports := make([]*types.Package, r.Len())
for i := range imports {
imports[i] = r.pkg()
}
pkg.SetImports(flattenImports(imports))
return pkg
}
// flattenImports returns the transitive closure of all imported
// packages rooted from pkgs.
func flattenImports(pkgs []*types.Package) []*types.Package {
var res []*types.Package
seen := make(map[*types.Package]struct{})
for _, pkg := range pkgs {
if _, ok := seen[pkg]; ok {
continue
}
seen[pkg] = struct{}{}
res = append(res, pkg)
// pkg.Imports() is already flattened.
for _, pkg := range pkg.Imports() {
if _, ok := seen[pkg]; ok {
continue
}
seen[pkg] = struct{}{}
res = append(res, pkg)
}
}
return res
}
// @@@ Types
func (r *reader) typ() types.Type {
return r.p.typIdx(r.typInfo(), r.dict)
}
func (r *reader) typInfo() typeInfo {
r.Sync(pkgbits.SyncType)
if r.Bool() {
return typeInfo{idx: pkgbits.Index(r.Len()), derived: true}
}
return typeInfo{idx: r.Reloc(pkgbits.RelocType), derived: false}
}
func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) types.Type {
idx := info.idx
var where *types.Type
if info.derived {
where = &dict.derivedTypes[idx]
idx = dict.derived[idx].idx
} else {
where = &pr.typs[idx]
}
if typ := *where; typ != nil {
return typ
}
var typ types.Type
{
r := pr.tempReader(pkgbits.RelocType, idx, pkgbits.SyncTypeIdx)
r.dict = dict
typ = r.doTyp()
assert(typ != nil)
pr.retireReader(r)
}
// See comment in pkgReader.typIdx explaining how this happens.
if prev := *where; prev != nil {
return prev
}
*where = typ
return typ
}
func (r *reader) doTyp() (res types.Type) {
switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
default:
errorf("unhandled type tag: %v", tag)
panic("unreachable")
case pkgbits.TypeBasic:
return types.Typ[r.Len()]
case pkgbits.TypeNamed:
obj, targs := r.obj()
name := obj.(*types.TypeName)
if len(targs) != 0 {
t, _ := types.Instantiate(r.p.ctxt, name.Type(), targs, false)
return t
}
return name.Type()
case pkgbits.TypeTypeParam:
return r.dict.tparams[r.Len()]
case pkgbits.TypeArray:
len := int64(r.Uint64())
return types.NewArray(r.typ(), len)
case pkgbits.TypeChan:
dir := types.ChanDir(r.Len())
return types.NewChan(dir, r.typ())
case pkgbits.TypeMap:
return types.NewMap(r.typ(), r.typ())
case pkgbits.TypePointer:
return types.NewPointer(r.typ())
case pkgbits.TypeSignature:
return r.signature(nil, nil, nil)
case pkgbits.TypeSlice:
return types.NewSlice(r.typ())
case pkgbits.TypeStruct:
return r.structType()
case pkgbits.TypeInterface:
return r.interfaceType()
case pkgbits.TypeUnion:
return r.unionType()
}
}
func (r *reader) structType() *types.Struct {
fields := make([]*types.Var, r.Len())
var tags []string
for i := range fields {
pos := r.pos()
pkg, name := r.selector()
ftyp := r.typ()
tag := r.String()
embedded := r.Bool()
fields[i] = types.NewField(pos, pkg, name, ftyp, embedded)
if tag != "" {
for len(tags) < i {
tags = append(tags, "")
}
tags = append(tags, tag)
}
}
return types.NewStruct(fields, tags)
}
func (r *reader) unionType() *types.Union {
terms := make([]*types.Term, r.Len())
for i := range terms {
terms[i] = types.NewTerm(r.Bool(), r.typ())
}
return types.NewUnion(terms)
}
func (r *reader) interfaceType() *types.Interface {
methods := make([]*types.Func, r.Len())
embeddeds := make([]types.Type, r.Len())
implicit := len(methods) == 0 && len(embeddeds) == 1 && r.Bool()
for i := range methods {
pos := r.pos()
pkg, name := r.selector()
mtyp := r.signature(nil, nil, nil)
methods[i] = types.NewFunc(pos, pkg, name, mtyp)
}
for i := range embeddeds {
embeddeds[i] = r.typ()
}
iface := types.NewInterfaceType(methods, embeddeds)
if implicit {
iface.MarkImplicit()
}
// We need to call iface.Complete(), but if there are any embedded
// defined types, then we may not have set their underlying
// interface type yet. So we need to defer calling Complete until
// after we've called SetUnderlying everywhere.
//
// TODO(mdempsky): After CL 424876 lands, it should be safe to call
// iface.Complete() immediately.
r.p.ifaces = append(r.p.ifaces, iface)
return iface
}
func (r *reader) signature(recv *types.Var, rtparams, tparams []*types.TypeParam) *types.Signature {
r.Sync(pkgbits.SyncSignature)
params := r.params()
results := r.params()
variadic := r.Bool()
return types.NewSignatureType(recv, rtparams, tparams, params, results, variadic)
}
func (r *reader) params() *types.Tuple {
r.Sync(pkgbits.SyncParams)
params := make([]*types.Var, r.Len())
for i := range params {
params[i] = r.param()
}
return types.NewTuple(params...)
}
func (r *reader) param() *types.Var {
r.Sync(pkgbits.SyncParam)
pos := r.pos()
pkg, name := r.localIdent()
typ := r.typ()
return types.NewParam(pos, pkg, name, typ)
}
// @@@ Objects
func (r *reader) obj() (types.Object, []types.Type) {
r.Sync(pkgbits.SyncObject)
assert(!r.Bool())
pkg, name := r.p.objIdx(r.Reloc(pkgbits.RelocObj))
obj := pkgScope(pkg).Lookup(name)
targs := make([]types.Type, r.Len())
for i := range targs {
targs[i] = r.typ()
}
return obj, targs
}
func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types.Package, string) {
var objPkg *types.Package
var objName string
var tag pkgbits.CodeObj
{
rname := pr.tempReader(pkgbits.RelocName, idx, pkgbits.SyncObject1)
objPkg, objName = rname.qualifiedIdent()
assert(objName != "")
tag = pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
pr.retireReader(rname)
}
if tag == pkgbits.ObjStub {
assert(objPkg == nil || objPkg == types.Unsafe)
return objPkg, objName
}
// Ignore local types promoted to global scope (#55110).
if _, suffix := splitVargenSuffix(objName); suffix != "" {
return objPkg, objName
}
if objPkg.Scope().Lookup(objName) == nil {
dict := pr.objDictIdx(idx)
r := pr.newReader(pkgbits.RelocObj, idx, pkgbits.SyncObject1)
r.dict = dict
declare := func(obj types.Object) {
objPkg.Scope().Insert(obj)
}
switch tag {
default:
panic("weird")
case pkgbits.ObjAlias:
pos := r.pos()
typ := r.typ()
declare(types.NewTypeName(pos, objPkg, objName, typ))
case pkgbits.ObjConst:
pos := r.pos()
typ := r.typ()
val := r.Value()
declare(types.NewConst(pos, objPkg, objName, typ, val))
case pkgbits.ObjFunc:
pos := r.pos()
tparams := r.typeParamNames()
sig := r.signature(nil, nil, tparams)
declare(types.NewFunc(pos, objPkg, objName, sig))
case pkgbits.ObjType:
pos := r.pos()
obj := types.NewTypeName(pos, objPkg, objName, nil)
named := types.NewNamed(obj, nil, nil)
declare(obj)
named.SetTypeParams(r.typeParamNames())
setUnderlying := func(underlying types.Type) {
// If the underlying type is an interface, we need to
// duplicate its methods so we can replace the receiver
// parameter's type (#49906).
if iface, ok := underlying.(*types.Interface); ok && iface.NumExplicitMethods() != 0 {
methods := make([]*types.Func, iface.NumExplicitMethods())
for i := range methods {
fn := iface.ExplicitMethod(i)
sig := fn.Type().(*types.Signature)
recv := types.NewVar(fn.Pos(), fn.Pkg(), "", named)
methods[i] = types.NewFunc(fn.Pos(), fn.Pkg(), fn.Name(), types.NewSignature(recv, sig.Params(), sig.Results(), sig.Variadic()))
}
embeds := make([]types.Type, iface.NumEmbeddeds())
for i := range embeds {
embeds[i] = iface.EmbeddedType(i)
}
newIface := types.NewInterfaceType(methods, embeds)
r.p.ifaces = append(r.p.ifaces, newIface)
underlying = newIface
}
named.SetUnderlying(underlying)
}
// Since go.dev/cl/455279, we can assume rhs.Underlying() will
// always be non-nil. However, to temporarily support users of
// older snapshot releases, we continue to fallback to the old
// behavior for now.
//
// TODO(mdempsky): Remove fallback code and simplify after
// allowing time for snapshot users to upgrade.
rhs := r.typ()
if underlying := rhs.Underlying(); underlying != nil {
setUnderlying(underlying)
} else {
pk := r.p
pk.laterFor(named, func() {
// First be sure that the rhs is initialized, if it needs to be initialized.
delete(pk.laterFors, named) // prevent cycles
if i, ok := pk.laterFors[rhs]; ok {
f := pk.laterFns[i]
pk.laterFns[i] = func() {} // function is running now, so replace it with a no-op
f() // initialize RHS
}
setUnderlying(rhs.Underlying())
})
}
for i, n := 0, r.Len(); i < n; i++ {
named.AddMethod(r.method())
}
case pkgbits.ObjVar:
pos := r.pos()
typ := r.typ()
declare(types.NewVar(pos, objPkg, objName, typ))
}
}
return objPkg, objName
}
func (pr *pkgReader) objDictIdx(idx pkgbits.Index) *readerDict {
var dict readerDict
{
r := pr.tempReader(pkgbits.RelocObjDict, idx, pkgbits.SyncObject1)
if implicits := r.Len(); implicits != 0 {
errorf("unexpected object with %v implicit type parameter(s)", implicits)
}
dict.bounds = make([]typeInfo, r.Len())
for i := range dict.bounds {
dict.bounds[i] = r.typInfo()
}
dict.derived = make([]derivedInfo, r.Len())
dict.derivedTypes = make([]types.Type, len(dict.derived))
for i := range dict.derived {
dict.derived[i] = derivedInfo{r.Reloc(pkgbits.RelocType), r.Bool()}
}
pr.retireReader(r)
}
// function references follow, but reader doesn't need those
return &dict
}
func (r *reader) typeParamNames() []*types.TypeParam {
r.Sync(pkgbits.SyncTypeParamNames)
// Note: This code assumes it only processes objects without
// implement type parameters. This is currently fine, because
// reader is only used to read in exported declarations, which are
// always package scoped.
if len(r.dict.bounds) == 0 {
return nil
}
// Careful: Type parameter lists may have cycles. To allow for this,
// we construct the type parameter list in two passes: first we
// create all the TypeNames and TypeParams, then we construct and
// set the bound type.
r.dict.tparams = make([]*types.TypeParam, len(r.dict.bounds))
for i := range r.dict.bounds {
pos := r.pos()
pkg, name := r.localIdent()
tname := types.NewTypeName(pos, pkg, name, nil)
r.dict.tparams[i] = types.NewTypeParam(tname, nil)
}
typs := make([]types.Type, len(r.dict.bounds))
for i, bound := range r.dict.bounds {
typs[i] = r.p.typIdx(bound, r.dict)
}
// TODO(mdempsky): This is subtle, elaborate further.
//
// We have to save tparams outside of the closure, because
// typeParamNames() can be called multiple times with the same
// dictionary instance.
//
// Also, this needs to happen later to make sure SetUnderlying has
// been called.
//
// TODO(mdempsky): Is it safe to have a single "later" slice or do
// we need to have multiple passes? See comments on CL 386002 and
// go.dev/issue/52104.
tparams := r.dict.tparams
r.p.later(func() {
for i, typ := range typs {
tparams[i].SetConstraint(typ)
}
})
return r.dict.tparams
}
func (r *reader) method() *types.Func {
r.Sync(pkgbits.SyncMethod)
pos := r.pos()
pkg, name := r.selector()
rparams := r.typeParamNames()
sig := r.signature(r.param(), rparams, nil)
_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
return types.NewFunc(pos, pkg, name, sig)
}
func (r *reader) qualifiedIdent() (*types.Package, string) { return r.ident(pkgbits.SyncSym) }
func (r *reader) localIdent() (*types.Package, string) { return r.ident(pkgbits.SyncLocalIdent) }
func (r *reader) selector() (*types.Package, string) { return r.ident(pkgbits.SyncSelector) }
func (r *reader) ident(marker pkgbits.SyncMarker) (*types.Package, string) {
r.Sync(marker)
return r.pkg(), r.String()
}
// pkgScope returns pkg.Scope().
// If pkg is nil, it returns types.Universe instead.
//
// TODO(mdempsky): Remove after x/tools can depend on Go 1.19.
func pkgScope(pkg *types.Package) *types.Scope {
if pkg != nil {
return pkg.Scope()
}
return types.Universe
}