mirror of https://go.googlesource.com/go
333 lines
13 KiB
Go
333 lines
13 KiB
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 types
|
|
|
|
import (
|
|
"fmt"
|
|
"go/ast"
|
|
"go/token"
|
|
. "internal/types/errors"
|
|
)
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// API
|
|
|
|
// A Signature represents a (non-builtin) function or method type.
|
|
// The receiver is ignored when comparing signatures for identity.
|
|
type Signature struct {
|
|
// We need to keep the scope in Signature (rather than passing it around
|
|
// and store it in the Func Object) because when type-checking a function
|
|
// literal we call the general type checker which returns a general Type.
|
|
// We then unpack the *Signature and use the scope for the literal body.
|
|
rparams *TypeParamList // receiver type parameters from left to right, or nil
|
|
tparams *TypeParamList // type parameters from left to right, or nil
|
|
scope *Scope // function scope for package-local and non-instantiated signatures; nil otherwise
|
|
recv *Var // nil if not a method
|
|
params *Tuple // (incoming) parameters from left to right; or nil
|
|
results *Tuple // (outgoing) results from left to right; or nil
|
|
variadic bool // true if the last parameter's type is of the form ...T (or string, for append built-in only)
|
|
}
|
|
|
|
// NewSignature returns a new function type for the given receiver, parameters,
|
|
// and results, either of which may be nil. If variadic is set, the function
|
|
// is variadic, it must have at least one parameter, and the last parameter
|
|
// must be of unnamed slice type.
|
|
//
|
|
// Deprecated: Use [NewSignatureType] instead which allows for type parameters.
|
|
func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
|
|
return NewSignatureType(recv, nil, nil, params, results, variadic)
|
|
}
|
|
|
|
// NewSignatureType creates a new function type for the given receiver,
|
|
// receiver type parameters, type parameters, parameters, and results. If
|
|
// variadic is set, params must hold at least one parameter and the last
|
|
// parameter's core type must be of unnamed slice or bytestring type.
|
|
// If recv is non-nil, typeParams must be empty. If recvTypeParams is
|
|
// non-empty, recv must be non-nil.
|
|
func NewSignatureType(recv *Var, recvTypeParams, typeParams []*TypeParam, params, results *Tuple, variadic bool) *Signature {
|
|
if variadic {
|
|
n := params.Len()
|
|
if n == 0 {
|
|
panic("variadic function must have at least one parameter")
|
|
}
|
|
core := coreString(params.At(n - 1).typ)
|
|
if _, ok := core.(*Slice); !ok && !isString(core) {
|
|
panic(fmt.Sprintf("got %s, want variadic parameter with unnamed slice type or string as core type", core.String()))
|
|
}
|
|
}
|
|
sig := &Signature{recv: recv, params: params, results: results, variadic: variadic}
|
|
if len(recvTypeParams) != 0 {
|
|
if recv == nil {
|
|
panic("function with receiver type parameters must have a receiver")
|
|
}
|
|
sig.rparams = bindTParams(recvTypeParams)
|
|
}
|
|
if len(typeParams) != 0 {
|
|
if recv != nil {
|
|
panic("function with type parameters cannot have a receiver")
|
|
}
|
|
sig.tparams = bindTParams(typeParams)
|
|
}
|
|
return sig
|
|
}
|
|
|
|
// Recv returns the receiver of signature s (if a method), or nil if a
|
|
// function. It is ignored when comparing signatures for identity.
|
|
//
|
|
// For an abstract method, Recv returns the enclosing interface either
|
|
// as a *[Named] or an *[Interface]. Due to embedding, an interface may
|
|
// contain methods whose receiver type is a different interface.
|
|
func (s *Signature) Recv() *Var { return s.recv }
|
|
|
|
// TypeParams returns the type parameters of signature s, or nil.
|
|
func (s *Signature) TypeParams() *TypeParamList { return s.tparams }
|
|
|
|
// RecvTypeParams returns the receiver type parameters of signature s, or nil.
|
|
func (s *Signature) RecvTypeParams() *TypeParamList { return s.rparams }
|
|
|
|
// Params returns the parameters of signature s, or nil.
|
|
func (s *Signature) Params() *Tuple { return s.params }
|
|
|
|
// Results returns the results of signature s, or nil.
|
|
func (s *Signature) Results() *Tuple { return s.results }
|
|
|
|
// Variadic reports whether the signature s is variadic.
|
|
func (s *Signature) Variadic() bool { return s.variadic }
|
|
|
|
func (t *Signature) Underlying() Type { return t }
|
|
func (t *Signature) String() string { return TypeString(t, nil) }
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Implementation
|
|
|
|
// funcType type-checks a function or method type.
|
|
func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
|
|
check.openScope(ftyp, "function")
|
|
check.scope.isFunc = true
|
|
check.recordScope(ftyp, check.scope)
|
|
sig.scope = check.scope
|
|
defer check.closeScope()
|
|
|
|
if recvPar != nil && len(recvPar.List) > 0 {
|
|
// collect generic receiver type parameters, if any
|
|
// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
|
|
// - the receiver specification acts as local declaration for its type parameters, which may be blank
|
|
_, rname, rparams := check.unpackRecv(recvPar.List[0].Type, true)
|
|
if len(rparams) > 0 {
|
|
// The scope of the type parameter T in "func (r T[T]) f()"
|
|
// starts after f, not at "r"; see #52038.
|
|
scopePos := ftyp.Params.Pos()
|
|
tparams := check.declareTypeParams(nil, rparams, scopePos)
|
|
sig.rparams = bindTParams(tparams)
|
|
// Blank identifiers don't get declared, so naive type-checking of the
|
|
// receiver type expression would fail in Checker.collectParams below,
|
|
// when Checker.ident cannot resolve the _ to a type.
|
|
//
|
|
// Checker.recvTParamMap maps these blank identifiers to their type parameter
|
|
// types, so that they may be resolved in Checker.ident when they fail
|
|
// lookup in the scope.
|
|
for i, p := range rparams {
|
|
if p.Name == "_" {
|
|
if check.recvTParamMap == nil {
|
|
check.recvTParamMap = make(map[*ast.Ident]*TypeParam)
|
|
}
|
|
check.recvTParamMap[p] = tparams[i]
|
|
}
|
|
}
|
|
// determine receiver type to get its type parameters
|
|
// and the respective type parameter bounds
|
|
var recvTParams []*TypeParam
|
|
if rname != nil {
|
|
// recv should be a Named type (otherwise an error is reported elsewhere)
|
|
// Also: Don't report an error via genericType since it will be reported
|
|
// again when we type-check the signature.
|
|
// TODO(gri) maybe the receiver should be marked as invalid instead?
|
|
if recv := asNamed(check.genericType(rname, nil)); recv != nil {
|
|
recvTParams = recv.TypeParams().list()
|
|
}
|
|
}
|
|
// provide type parameter bounds
|
|
if len(tparams) == len(recvTParams) {
|
|
smap := makeRenameMap(recvTParams, tparams)
|
|
for i, tpar := range tparams {
|
|
recvTPar := recvTParams[i]
|
|
check.mono.recordCanon(tpar, recvTPar)
|
|
// recvTPar.bound is (possibly) parameterized in the context of the
|
|
// receiver type declaration. Substitute parameters for the current
|
|
// context.
|
|
tpar.bound = check.subst(tpar.obj.pos, recvTPar.bound, smap, nil, check.context())
|
|
}
|
|
} else if len(tparams) < len(recvTParams) {
|
|
// Reporting an error here is a stop-gap measure to avoid crashes in the
|
|
// compiler when a type parameter/argument cannot be inferred later. It
|
|
// may lead to follow-on errors (see issues go.dev/issue/51339, go.dev/issue/51343).
|
|
// TODO(gri) find a better solution
|
|
got := measure(len(tparams), "type parameter")
|
|
check.errorf(recvPar, BadRecv, "got %s, but receiver base type declares %d", got, len(recvTParams))
|
|
}
|
|
}
|
|
}
|
|
|
|
if ftyp.TypeParams != nil {
|
|
check.collectTypeParams(&sig.tparams, ftyp.TypeParams)
|
|
// Always type-check method type parameters but complain that they are not allowed.
|
|
// (A separate check is needed when type-checking interface method signatures because
|
|
// they don't have a receiver specification.)
|
|
if recvPar != nil {
|
|
check.error(ftyp.TypeParams, InvalidMethodTypeParams, "methods cannot have type parameters")
|
|
}
|
|
}
|
|
|
|
// Use a temporary scope for all parameter declarations and then
|
|
// squash that scope into the parent scope (and report any
|
|
// redeclarations at that time).
|
|
//
|
|
// TODO(adonovan): now that each declaration has the correct
|
|
// scopePos, there should be no need for scope squashing.
|
|
// Audit to ensure all lookups honor scopePos and simplify.
|
|
scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)")
|
|
scopePos := ftyp.End() // all parameters' scopes start after the signature
|
|
recvList, _ := check.collectParams(scope, recvPar, false, scopePos)
|
|
params, variadic := check.collectParams(scope, ftyp.Params, true, scopePos)
|
|
results, _ := check.collectParams(scope, ftyp.Results, false, scopePos)
|
|
scope.squash(func(obj, alt Object) {
|
|
err := check.newError(DuplicateDecl)
|
|
err.addf(obj, "%s redeclared in this block", obj.Name())
|
|
err.addAltDecl(alt)
|
|
err.report()
|
|
})
|
|
|
|
if recvPar != nil {
|
|
// recv parameter list present (may be empty)
|
|
// spec: "The receiver is specified via an extra parameter section preceding the
|
|
// method name. That parameter section must declare a single parameter, the receiver."
|
|
var recv *Var
|
|
switch len(recvList) {
|
|
case 0:
|
|
// error reported by resolver
|
|
recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below
|
|
default:
|
|
// more than one receiver
|
|
check.error(recvList[len(recvList)-1], InvalidRecv, "method has multiple receivers")
|
|
fallthrough // continue with first receiver
|
|
case 1:
|
|
recv = recvList[0]
|
|
}
|
|
sig.recv = recv
|
|
|
|
// Delay validation of receiver type as it may cause premature expansion
|
|
// of types the receiver type is dependent on (see issues go.dev/issue/51232, go.dev/issue/51233).
|
|
check.later(func() {
|
|
// spec: "The receiver type must be of the form T or *T where T is a type name."
|
|
rtyp, _ := deref(recv.typ)
|
|
atyp := Unalias(rtyp)
|
|
if !isValid(atyp) {
|
|
return // error was reported before
|
|
}
|
|
// spec: "The type denoted by T is called the receiver base type; it must not
|
|
// be a pointer or interface type and it must be declared in the same package
|
|
// as the method."
|
|
switch T := atyp.(type) {
|
|
case *Named:
|
|
// The receiver type may be an instantiated type referred to
|
|
// by an alias (which cannot have receiver parameters for now).
|
|
if T.TypeArgs() != nil && sig.RecvTypeParams() == nil {
|
|
check.errorf(recv, InvalidRecv, "cannot define new methods on instantiated type %s", rtyp)
|
|
break
|
|
}
|
|
if T.obj.pkg != check.pkg {
|
|
check.errorf(recv, InvalidRecv, "cannot define new methods on non-local type %s", rtyp)
|
|
break
|
|
}
|
|
var cause string
|
|
switch u := T.under().(type) {
|
|
case *Basic:
|
|
// unsafe.Pointer is treated like a regular pointer
|
|
if u.kind == UnsafePointer {
|
|
cause = "unsafe.Pointer"
|
|
}
|
|
case *Pointer, *Interface:
|
|
cause = "pointer or interface type"
|
|
case *TypeParam:
|
|
// The underlying type of a receiver base type cannot be a
|
|
// type parameter: "type T[P any] P" is not a valid declaration.
|
|
panic("unreachable")
|
|
}
|
|
if cause != "" {
|
|
check.errorf(recv, InvalidRecv, "invalid receiver type %s (%s)", rtyp, cause)
|
|
}
|
|
case *Basic:
|
|
check.errorf(recv, InvalidRecv, "cannot define new methods on non-local type %s", rtyp)
|
|
default:
|
|
check.errorf(recv, InvalidRecv, "invalid receiver type %s", recv.typ)
|
|
}
|
|
}).describef(recv, "validate receiver %s", recv)
|
|
}
|
|
|
|
sig.params = NewTuple(params...)
|
|
sig.results = NewTuple(results...)
|
|
sig.variadic = variadic
|
|
}
|
|
|
|
// collectParams declares the parameters of list in scope and returns the corresponding
|
|
// variable list.
|
|
func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, variadicOk bool, scopePos token.Pos) (params []*Var, variadic bool) {
|
|
if list == nil {
|
|
return
|
|
}
|
|
|
|
var named, anonymous bool
|
|
for i, field := range list.List {
|
|
ftype := field.Type
|
|
if t, _ := ftype.(*ast.Ellipsis); t != nil {
|
|
ftype = t.Elt
|
|
if variadicOk && i == len(list.List)-1 && len(field.Names) <= 1 {
|
|
variadic = true
|
|
} else {
|
|
check.softErrorf(t, MisplacedDotDotDot, "can only use ... with final parameter in list")
|
|
// ignore ... and continue
|
|
}
|
|
}
|
|
typ := check.varType(ftype)
|
|
// The parser ensures that f.Tag is nil and we don't
|
|
// care if a constructed AST contains a non-nil tag.
|
|
if len(field.Names) > 0 {
|
|
// named parameter
|
|
for _, name := range field.Names {
|
|
if name.Name == "" {
|
|
check.error(name, InvalidSyntaxTree, "anonymous parameter")
|
|
// ok to continue
|
|
}
|
|
par := NewParam(name.Pos(), check.pkg, name.Name, typ)
|
|
check.declare(scope, name, par, scopePos)
|
|
params = append(params, par)
|
|
}
|
|
named = true
|
|
} else {
|
|
// anonymous parameter
|
|
par := NewParam(ftype.Pos(), check.pkg, "", typ)
|
|
check.recordImplicit(field, par)
|
|
params = append(params, par)
|
|
anonymous = true
|
|
}
|
|
}
|
|
|
|
if named && anonymous {
|
|
check.error(list, InvalidSyntaxTree, "list contains both named and anonymous parameters")
|
|
// ok to continue
|
|
}
|
|
|
|
// For a variadic function, change the last parameter's type from T to []T.
|
|
// Since we type-checked T rather than ...T, we also need to retro-actively
|
|
// record the type for ...T.
|
|
if variadic {
|
|
last := params[len(params)-1]
|
|
last.typ = &Slice{elem: last.typ}
|
|
check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
|
|
}
|
|
|
|
return
|
|
}
|