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[dev.typeparams] go/types: move signature checking into separate file

This is a port of CL 321590 to go/types. Specifically, the same checker
methods were moved.

Change-Id: If4522d316f29c6b6f887580aa037e6b6dedbb6ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/324754
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley 2021-06-03 11:13:38 -04:00 committed by Robert Findley
parent c23294d6b3
commit 991dca0112
2 changed files with 274 additions and 262 deletions

274
src/go/types/signature.go Normal file
View File

@ -0,0 +1,274 @@
// 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/internal/typeparams"
"go/token"
)
// 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()
var recvTyp ast.Expr // rewritten receiver type; valid if != nil
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 {
// Blank identifiers don't get declared and regular type-checking of the instantiated
// parameterized receiver type expression fails in Checker.collectParams of receiver.
// Identify blank type parameters and substitute each with a unique new identifier named
// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
// name.
var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
for i, p := range rparams {
if p.Name == "_" {
new := *p
new.Name = fmt.Sprintf("%d_", i)
rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
if smap == nil {
smap = make(map[*ast.Ident]*ast.Ident)
}
smap[p] = &new
}
}
if smap != nil {
// blank identifiers were found => use rewritten receiver type
recvTyp = isubst(recvPar.List[0].Type, smap)
}
sig.rparams = check.declareTypeParams(nil, rparams)
// determine receiver type to get its type parameters
// and the respective type parameter bounds
var recvTParams []*TypeName
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, false)); recv != nil {
recvTParams = recv.tparams
}
}
// provide type parameter bounds
// - only do this if we have the right number (otherwise an error is reported elsewhere)
if len(sig.rparams) == len(recvTParams) {
// We have a list of *TypeNames but we need a list of Types.
list := make([]Type, len(sig.rparams))
for i, t := range sig.rparams {
list[i] = t.typ
}
smap := makeSubstMap(recvTParams, list)
for i, tname := range sig.rparams {
bound := recvTParams[i].typ.(*_TypeParam).bound
// bound is (possibly) parameterized in the context of the
// receiver type declaration. Substitute parameters for the
// current context.
// TODO(gri) should we assume now that bounds always exist?
// (no bound == empty interface)
if bound != nil {
bound = check.subst(tname.pos, bound, smap)
tname.typ.(*_TypeParam).bound = bound
}
}
}
}
}
if tparams := typeparams.Get(ftyp); tparams != nil {
sig.tparams = check.collectTypeParams(tparams)
// 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.errorf(tparams, _Todo, "methods cannot have type parameters")
}
}
// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
// declarations and then squash that scope into the parent scope (and report any redeclarations at
// that time).
scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
results, _ := check.collectParams(scope, ftyp.Results, nil, false)
scope.squash(func(obj, alt Object) {
check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
check.reportAltDecl(alt)
})
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(0, nil, "", Typ[Invalid]) // ignore recv below
default:
// more than one receiver
check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
fallthrough // continue with first receiver
case 1:
recv = recvList[0]
}
// TODO(gri) We should delay rtyp expansion to when we actually need the
// receiver; thus all checks here should be delayed to later.
rtyp, _ := deref(recv.typ)
rtyp = expand(rtyp)
// spec: "The receiver type must be of the form T or *T where T is a type name."
// (ignore invalid types - error was reported before)
if t := rtyp; t != Typ[Invalid] {
var err string
if T := asNamed(t); T != nil {
// 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."
if T.obj.pkg != check.pkg {
err = "type not defined in this package"
} else {
switch u := optype(T).(type) {
case *Basic:
// unsafe.Pointer is treated like a regular pointer
if u.kind == UnsafePointer {
err = "unsafe.Pointer"
}
case *Pointer, *Interface:
err = "pointer or interface type"
}
}
} else {
err = "basic or unnamed type"
}
if err != "" {
check.errorf(recv, _InvalidRecv, "invalid receiver %s (%s)", recv.typ, err)
// ok to continue
}
}
sig.recv = 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. If type0 != nil, it is used instead of the first type in list.
func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
if list == nil {
return
}
var named, anonymous bool
for i, field := range list.List {
ftype := field.Type
if i == 0 && type0 != nil {
ftype = type0
}
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.invalidAST(name, "anonymous parameter")
// ok to continue
}
par := NewParam(name.Pos(), check.pkg, name.Name, typ)
check.declare(scope, name, par, scope.pos)
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.invalidAST(list, "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
}
// isubst returns an x with identifiers substituted per the substitution map smap.
// isubst only handles the case of (valid) method receiver type expressions correctly.
func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
switch n := x.(type) {
case *ast.Ident:
if alt := smap[n]; alt != nil {
return alt
}
case *ast.StarExpr:
X := isubst(n.X, smap)
if X != n.X {
new := *n
new.X = X
return &new
}
case *ast.IndexExpr:
elems := typeparams.UnpackExpr(n.Index)
var newElems []ast.Expr
for i, elem := range elems {
new := isubst(elem, smap)
if new != elem {
if newElems == nil {
newElems = make([]ast.Expr, len(elems))
copy(newElems, elems)
}
newElems[i] = new
}
}
if newElems != nil {
index := typeparams.PackExpr(newElems)
new := *n
new.Index = index
return &new
}
case *ast.ParenExpr:
return isubst(n.X, smap) // no need to keep parentheses
default:
// Other receiver type expressions are invalid.
// It's fine to ignore those here as they will
// be checked elsewhere.
}
return x
}

View File

@ -192,205 +192,6 @@ func (check *Checker) genericType(e ast.Expr, reportErr bool) Type {
return typ
}
// isubst returns an x with identifiers substituted per the substitution map smap.
// isubst only handles the case of (valid) method receiver type expressions correctly.
func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
switch n := x.(type) {
case *ast.Ident:
if alt := smap[n]; alt != nil {
return alt
}
case *ast.StarExpr:
X := isubst(n.X, smap)
if X != n.X {
new := *n
new.X = X
return &new
}
case *ast.IndexExpr:
elems := typeparams.UnpackExpr(n.Index)
var newElems []ast.Expr
for i, elem := range elems {
new := isubst(elem, smap)
if new != elem {
if newElems == nil {
newElems = make([]ast.Expr, len(elems))
copy(newElems, elems)
}
newElems[i] = new
}
}
if newElems != nil {
index := typeparams.PackExpr(newElems)
new := *n
new.Index = index
return &new
}
case *ast.ParenExpr:
return isubst(n.X, smap) // no need to keep parentheses
default:
// Other receiver type expressions are invalid.
// It's fine to ignore those here as they will
// be checked elsewhere.
}
return x
}
// 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()
var recvTyp ast.Expr // rewritten receiver type; valid if != nil
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 {
// Blank identifiers don't get declared and regular type-checking of the instantiated
// parameterized receiver type expression fails in Checker.collectParams of receiver.
// Identify blank type parameters and substitute each with a unique new identifier named
// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
// name.
var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
for i, p := range rparams {
if p.Name == "_" {
new := *p
new.Name = fmt.Sprintf("%d_", i)
rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
if smap == nil {
smap = make(map[*ast.Ident]*ast.Ident)
}
smap[p] = &new
}
}
if smap != nil {
// blank identifiers were found => use rewritten receiver type
recvTyp = isubst(recvPar.List[0].Type, smap)
}
sig.rparams = check.declareTypeParams(nil, rparams)
// determine receiver type to get its type parameters
// and the respective type parameter bounds
var recvTParams []*TypeName
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, false)); recv != nil {
recvTParams = recv.tparams
}
}
// provide type parameter bounds
// - only do this if we have the right number (otherwise an error is reported elsewhere)
if len(sig.rparams) == len(recvTParams) {
// We have a list of *TypeNames but we need a list of Types.
list := make([]Type, len(sig.rparams))
for i, t := range sig.rparams {
list[i] = t.typ
}
smap := makeSubstMap(recvTParams, list)
for i, tname := range sig.rparams {
bound := recvTParams[i].typ.(*_TypeParam).bound
// bound is (possibly) parameterized in the context of the
// receiver type declaration. Substitute parameters for the
// current context.
// TODO(gri) should we assume now that bounds always exist?
// (no bound == empty interface)
if bound != nil {
bound = check.subst(tname.pos, bound, smap)
tname.typ.(*_TypeParam).bound = bound
}
}
}
}
}
if tparams := typeparams.Get(ftyp); tparams != nil {
sig.tparams = check.collectTypeParams(tparams)
// 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.errorf(tparams, _Todo, "methods cannot have type parameters")
}
}
// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
// declarations and then squash that scope into the parent scope (and report any redeclarations at
// that time).
scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
results, _ := check.collectParams(scope, ftyp.Results, nil, false)
scope.squash(func(obj, alt Object) {
check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
check.reportAltDecl(alt)
})
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(0, nil, "", Typ[Invalid]) // ignore recv below
default:
// more than one receiver
check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
fallthrough // continue with first receiver
case 1:
recv = recvList[0]
}
// TODO(gri) We should delay rtyp expansion to when we actually need the
// receiver; thus all checks here should be delayed to later.
rtyp, _ := deref(recv.typ)
rtyp = expand(rtyp)
// spec: "The receiver type must be of the form T or *T where T is a type name."
// (ignore invalid types - error was reported before)
if t := rtyp; t != Typ[Invalid] {
var err string
if T := asNamed(t); T != nil {
// 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."
if T.obj.pkg != check.pkg {
err = "type not defined in this package"
} else {
switch u := optype(T).(type) {
case *Basic:
// unsafe.Pointer is treated like a regular pointer
if u.kind == UnsafePointer {
err = "unsafe.Pointer"
}
case *Pointer, *Interface:
err = "pointer or interface type"
}
}
} else {
err = "basic or unnamed type"
}
if err != "" {
check.errorf(recv, _InvalidRecv, "invalid receiver %s (%s)", recv.typ, err)
// ok to continue
}
}
sig.recv = recv
}
sig.params = NewTuple(params...)
sig.results = NewTuple(results...)
sig.variadic = variadic
}
// goTypeName returns the Go type name for typ and
// removes any occurrences of "types." from that name.
func goTypeName(typ Type) string {
@ -683,66 +484,3 @@ func (check *Checker) typeList(list []ast.Expr) []Type {
}
return res
}
// collectParams declares the parameters of list in scope and returns the corresponding
// variable list. If type0 != nil, it is used instead of the first type in list.
func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
if list == nil {
return
}
var named, anonymous bool
for i, field := range list.List {
ftype := field.Type
if i == 0 && type0 != nil {
ftype = type0
}
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.invalidAST(name, "anonymous parameter")
// ok to continue
}
par := NewParam(name.Pos(), check.pkg, name.Name, typ)
check.declare(scope, name, par, scope.pos)
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.invalidAST(list, "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
}