--- /dev/null
+// 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 types2
+
+import (
+ "cmd/compile/internal/syntax"
+ "fmt"
+)
+
+// Disabled by default, but enabled when running tests (via types_test.go).
+var acceptMethodTypeParams bool
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
+ check.openScope(ftyp, "function")
+ check.scope.isFunc = true
+ check.recordScope(ftyp, check.scope)
+ sig.scope = check.scope
+ defer check.closeScope()
+
+ var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
+ if recvPar != nil {
+ // 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.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[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
+ for i, p := range rparams {
+ if p.Value == "_" {
+ new := *p
+ new.Value = fmt.Sprintf("%d_", i)
+ rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
+ if smap == nil {
+ smap = make(map[*syntax.Name]*syntax.Name)
+ }
+ smap[p] = &new
+ }
+ }
+ if smap != nil {
+ // blank identifiers were found => use rewritten receiver type
+ recvTyp = isubst(recvPar.Type, smap)
+ }
+ // TODO(gri) rework declareTypeParams
+ sig.rparams = nil
+ for _, rparam := range rparams {
+ sig.rparams = check.declareTypeParam(sig.rparams, rparam)
+ }
+ // 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 != nil {
+ sig.tparams = check.collectTypeParams(tparams)
+ // Always type-check method type parameters but complain if they are not enabled.
+ // (A separate check is needed when type-checking interface method signatures because
+ // they don't have a receiver specification.)
+ if recvPar != nil && !acceptMethodTypeParams {
+ check.error(ftyp, "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, nopos, nopos, "function body (temp. scope)")
+ var recvList []*Var // TODO(gri) remove the need for making a list here
+ if recvPar != nil {
+ recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
+ }
+ params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
+ results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
+ scope.Squash(func(obj, alt Object) {
+ var err error_
+ err.errorf(obj, "%s redeclared in this block", obj.Name())
+ err.recordAltDecl(alt)
+ check.report(&err)
+ })
+
+ 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].Pos(), "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"
+ if check.conf.CompilerErrorMessages {
+ check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+ err = ""
+ }
+ } 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 if T := asBasic(t); T != nil {
+ err = "basic or unnamed type"
+ if check.conf.CompilerErrorMessages {
+ check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+ err = ""
+ }
+ } else {
+ check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
+ }
+ if err != "" {
+ check.errorf(recv.pos, "invalid receiver type %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 []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
+ if list == nil {
+ return
+ }
+
+ var named, anonymous bool
+
+ var typ Type
+ var prev syntax.Expr
+ for i, field := range list {
+ ftype := field.Type
+ // type-check type of grouped fields only once
+ if ftype != prev {
+ prev = ftype
+ if i == 0 && type0 != nil {
+ ftype = type0
+ }
+ if t, _ := ftype.(*syntax.DotsType); t != nil {
+ ftype = t.Elem
+ if variadicOk && i == len(list)-1 {
+ variadic = true
+ } else {
+ check.softErrorf(t, "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 field.Name != nil {
+ // named parameter
+ name := field.Name.Value
+ if name == "" {
+ check.error(field.Name, invalidAST+"anonymous parameter")
+ // ok to continue
+ }
+ par := NewParam(field.Name.Pos(), check.pkg, name, typ)
+ check.declare(scope, field.Name, par, scope.pos)
+ params = append(params, par)
+ named = true
+ } else {
+ // anonymous parameter
+ par := NewParam(field.Pos(), check.pkg, "", typ)
+ check.recordImplicit(field, par)
+ params = append(params, par)
+ anonymous = true
+ }
+ }
+
+ if named && anonymous {
+ check.error(list[0], invalidAST+"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[len(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 syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
+ switch n := x.(type) {
+ case *syntax.Name:
+ if alt := smap[n]; alt != nil {
+ return alt
+ }
+ // case *syntax.StarExpr:
+ // X := isubst(n.X, smap)
+ // if X != n.X {
+ // new := *n
+ // new.X = X
+ // return &new
+ // }
+ case *syntax.Operation:
+ if n.Op == syntax.Mul && n.Y == nil {
+ X := isubst(n.X, smap)
+ if X != n.X {
+ new := *n
+ new.X = X
+ return &new
+ }
+ }
+ case *syntax.IndexExpr:
+ Index := isubst(n.Index, smap)
+ if Index != n.Index {
+ new := *n
+ new.Index = Index
+ return &new
+ }
+ case *syntax.ListExpr:
+ var elems []syntax.Expr
+ for i, elem := range n.ElemList {
+ new := isubst(elem, smap)
+ if new != elem {
+ if elems == nil {
+ elems = make([]syntax.Expr, len(n.ElemList))
+ copy(elems, n.ElemList)
+ }
+ elems[i] = new
+ }
+ }
+ if elems != nil {
+ new := *n
+ new.ElemList = elems
+ return &new
+ }
+ case *syntax.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
+}
"strings"
)
-// Disabled by default, but enabled when running tests (via types_test.go).
-var acceptMethodTypeParams bool
-
// ident type-checks identifier e and initializes x with the value or type of e.
// If an error occurred, x.mode is set to invalid.
// For the meaning of def, see Checker.definedType, below.
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 syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
- switch n := x.(type) {
- case *syntax.Name:
- if alt := smap[n]; alt != nil {
- return alt
- }
- // case *syntax.StarExpr:
- // X := isubst(n.X, smap)
- // if X != n.X {
- // new := *n
- // new.X = X
- // return &new
- // }
- case *syntax.Operation:
- if n.Op == syntax.Mul && n.Y == nil {
- X := isubst(n.X, smap)
- if X != n.X {
- new := *n
- new.X = X
- return &new
- }
- }
- case *syntax.IndexExpr:
- Index := isubst(n.Index, smap)
- if Index != n.Index {
- new := *n
- new.Index = Index
- return &new
- }
- case *syntax.ListExpr:
- var elems []syntax.Expr
- for i, elem := range n.ElemList {
- new := isubst(elem, smap)
- if new != elem {
- if elems == nil {
- elems = make([]syntax.Expr, len(n.ElemList))
- copy(elems, n.ElemList)
- }
- elems[i] = new
- }
- }
- if elems != nil {
- new := *n
- new.ElemList = elems
- return &new
- }
- case *syntax.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 *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
- check.openScope(ftyp, "function")
- check.scope.isFunc = true
- check.recordScope(ftyp, check.scope)
- sig.scope = check.scope
- defer check.closeScope()
-
- var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
- if recvPar != nil {
- // 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.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[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
- for i, p := range rparams {
- if p.Value == "_" {
- new := *p
- new.Value = fmt.Sprintf("%d_", i)
- rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
- if smap == nil {
- smap = make(map[*syntax.Name]*syntax.Name)
- }
- smap[p] = &new
- }
- }
- if smap != nil {
- // blank identifiers were found => use rewritten receiver type
- recvTyp = isubst(recvPar.Type, smap)
- }
- // TODO(gri) rework declareTypeParams
- sig.rparams = nil
- for _, rparam := range rparams {
- sig.rparams = check.declareTypeParam(sig.rparams, rparam)
- }
- // 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 != nil {
- sig.tparams = check.collectTypeParams(tparams)
- // Always type-check method type parameters but complain if they are not enabled.
- // (A separate check is needed when type-checking interface method signatures because
- // they don't have a receiver specification.)
- if recvPar != nil && !acceptMethodTypeParams {
- check.error(ftyp, "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, nopos, nopos, "function body (temp. scope)")
- var recvList []*Var // TODO(gri) remove the need for making a list here
- if recvPar != nil {
- recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
- }
- params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
- results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
- scope.Squash(func(obj, alt Object) {
- var err error_
- err.errorf(obj, "%s redeclared in this block", obj.Name())
- err.recordAltDecl(alt)
- check.report(&err)
- })
-
- 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].Pos(), "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"
- if check.conf.CompilerErrorMessages {
- check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
- err = ""
- }
- } 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 if T := asBasic(t); T != nil {
- err = "basic or unnamed type"
- if check.conf.CompilerErrorMessages {
- check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
- err = ""
- }
- } else {
- check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
- }
- if err != "" {
- check.errorf(recv.pos, "invalid receiver type %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 "types2." from that name.
func goTypeName(typ Type) string {
}
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 []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
- if list == nil {
- return
- }
-
- var named, anonymous bool
-
- var typ Type
- var prev syntax.Expr
- for i, field := range list {
- ftype := field.Type
- // type-check type of grouped fields only once
- if ftype != prev {
- prev = ftype
- if i == 0 && type0 != nil {
- ftype = type0
- }
- if t, _ := ftype.(*syntax.DotsType); t != nil {
- ftype = t.Elem
- if variadicOk && i == len(list)-1 {
- variadic = true
- } else {
- check.softErrorf(t, "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 field.Name != nil {
- // named parameter
- name := field.Name.Value
- if name == "" {
- check.error(field.Name, invalidAST+"anonymous parameter")
- // ok to continue
- }
- par := NewParam(field.Name.Pos(), check.pkg, name, typ)
- check.declare(scope, field.Name, par, scope.pos)
- params = append(params, par)
- named = true
- } else {
- // anonymous parameter
- par := NewParam(field.Pos(), check.pkg, "", typ)
- check.recordImplicit(field, par)
- params = append(params, par)
- anonymous = true
- }
- }
-
- if named && anonymous {
- check.error(list[0], invalidAST+"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[len(list)-1].Type, typexpr, last.typ, nil)
- }
-
- return
-}