--- /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 types
+
+import (
+ "go/ast"
+ "go/internal/typeparams"
+ "go/token"
+ "sort"
+)
+
+func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
+ var tlist *ast.Ident // "type" name of first entry in a type list declaration
+ var types []ast.Expr
+ for _, f := range iface.Methods.List {
+ if len(f.Names) > 0 {
+ // We have a method with name f.Names[0], or a type
+ // of a type list (name.Name == "type").
+ // (The parser ensures that there's only one method
+ // and we don't care if a constructed AST has more.)
+ name := f.Names[0]
+ if name.Name == "_" {
+ check.errorf(name, _BlankIfaceMethod, "invalid method name _")
+ continue // ignore
+ }
+
+ if name.Name == "type" {
+ // Always collect all type list entries, even from
+ // different type lists, under the assumption that
+ // the author intended to include all types.
+ types = append(types, f.Type)
+ if tlist != nil && tlist != name {
+ check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
+ }
+ tlist = name
+ continue
+ }
+
+ typ := check.typ(f.Type)
+ sig, _ := typ.(*Signature)
+ if sig == nil {
+ if typ != Typ[Invalid] {
+ check.invalidAST(f.Type, "%s is not a method signature", typ)
+ }
+ continue // ignore
+ }
+
+ // Always type-check method type parameters but complain if they are not enabled.
+ // (This extra check is needed here because interface method signatures don't have
+ // a receiver specification.)
+ if sig.tparams != nil {
+ var at positioner = f.Type
+ if tparams := typeparams.Get(f.Type); tparams != nil {
+ at = tparams
+ }
+ check.errorf(at, _Todo, "methods cannot have type parameters")
+ }
+
+ // use named receiver type if available (for better error messages)
+ var recvTyp Type = ityp
+ if def != nil {
+ recvTyp = def
+ }
+ sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
+
+ m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
+ check.recordDef(name, m)
+ ityp.methods = append(ityp.methods, m)
+ } else {
+ // We have an embedded type. completeInterface will
+ // eventually verify that we have an interface.
+ ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
+ check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
+ }
+ }
+
+ // type constraints
+ ityp.types = _NewSum(check.collectTypeConstraints(iface.Pos(), types))
+
+ if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
+ // empty interface
+ ityp.allMethods = markComplete
+ return
+ }
+
+ // sort for API stability
+ sortMethods(ityp.methods)
+ sortTypes(ityp.embeddeds)
+
+ check.later(func() { check.completeInterface(iface.Pos(), ityp) })
+}
+
+func (check *Checker) collectTypeConstraints(pos token.Pos, types []ast.Expr) []Type {
+ list := make([]Type, 0, len(types)) // assume all types are correct
+ for _, texpr := range types {
+ if texpr == nil {
+ check.invalidAST(atPos(pos), "missing type constraint")
+ continue
+ }
+ list = append(list, check.varType(texpr))
+ }
+
+ // Ensure that each type is only present once in the type list. Types may be
+ // interfaces, which may not be complete yet. It's ok to do this check at the
+ // end because it's not a requirement for correctness of the code.
+ // Note: This is a quadratic algorithm, but type lists tend to be short.
+ check.later(func() {
+ for i, t := range list {
+ if t := asInterface(t); t != nil {
+ check.completeInterface(types[i].Pos(), t)
+ }
+ if includes(list[:i], t) {
+ check.softErrorf(types[i], _Todo, "duplicate type %s in type list", t)
+ }
+ }
+ })
+
+ return list
+}
+
+// includes reports whether typ is in list.
+func includes(list []Type, typ Type) bool {
+ for _, e := range list {
+ if Identical(typ, e) {
+ return true
+ }
+ }
+ return false
+}
+
+func (check *Checker) completeInterface(pos token.Pos, ityp *Interface) {
+ if ityp.allMethods != nil {
+ return
+ }
+
+ // completeInterface may be called via the LookupFieldOrMethod,
+ // MissingMethod, Identical, or IdenticalIgnoreTags external API
+ // in which case check will be nil. In this case, type-checking
+ // must be finished and all interfaces should have been completed.
+ if check == nil {
+ panic("internal error: incomplete interface")
+ }
+
+ if trace {
+ // Types don't generally have position information.
+ // If we don't have a valid pos provided, try to use
+ // one close enough.
+ if !pos.IsValid() && len(ityp.methods) > 0 {
+ pos = ityp.methods[0].pos
+ }
+
+ check.trace(pos, "complete %s", ityp)
+ check.indent++
+ defer func() {
+ check.indent--
+ check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
+ }()
+ }
+
+ // An infinitely expanding interface (due to a cycle) is detected
+ // elsewhere (Checker.validType), so here we simply assume we only
+ // have valid interfaces. Mark the interface as complete to avoid
+ // infinite recursion if the validType check occurs later for some
+ // reason.
+ ityp.allMethods = markComplete
+
+ // Methods of embedded interfaces are collected unchanged; i.e., the identity
+ // of a method I.m's Func Object of an interface I is the same as that of
+ // the method m in an interface that embeds interface I. On the other hand,
+ // if a method is embedded via multiple overlapping embedded interfaces, we
+ // don't provide a guarantee which "original m" got chosen for the embedding
+ // interface. See also issue #34421.
+ //
+ // If we don't care to provide this identity guarantee anymore, instead of
+ // reusing the original method in embeddings, we can clone the method's Func
+ // Object and give it the position of a corresponding embedded interface. Then
+ // we can get rid of the mpos map below and simply use the cloned method's
+ // position.
+
+ var seen objset
+ var methods []*Func
+ mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
+ addMethod := func(pos token.Pos, m *Func, explicit bool) {
+ switch other := seen.insert(m); {
+ case other == nil:
+ methods = append(methods, m)
+ mpos[m] = pos
+ case explicit:
+ check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+ check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+ default:
+ // We have a duplicate method name in an embedded (not explicitly declared) method.
+ // Check method signatures after all types are computed (issue #33656).
+ // If we're pre-go1.14 (overlapping embeddings are not permitted), report that
+ // error here as well (even though we could do it eagerly) because it's the same
+ // error message.
+ check.later(func() {
+ if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
+ check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+ check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+ }
+ })
+ }
+ }
+
+ for _, m := range ityp.methods {
+ addMethod(m.pos, m, true)
+ }
+
+ // collect types
+ allTypes := ityp.types
+
+ posList := check.posMap[ityp]
+ for i, typ := range ityp.embeddeds {
+ pos := posList[i] // embedding position
+ utyp := under(typ)
+ etyp := asInterface(utyp)
+ if etyp == nil {
+ if utyp != Typ[Invalid] {
+ var format string
+ if _, ok := utyp.(*_TypeParam); ok {
+ format = "%s is a type parameter, not an interface"
+ } else {
+ format = "%s is not an interface"
+ }
+ // TODO: correct error code.
+ check.errorf(atPos(pos), _InvalidIfaceEmbed, format, typ)
+ }
+ continue
+ }
+ check.completeInterface(pos, etyp)
+ for _, m := range etyp.allMethods {
+ addMethod(pos, m, false) // use embedding position pos rather than m.pos
+ }
+ allTypes = intersect(allTypes, etyp.allTypes)
+ }
+
+ if methods != nil {
+ sort.Sort(byUniqueMethodName(methods))
+ ityp.allMethods = methods
+ }
+ ityp.allTypes = allTypes
+}
+
+// intersect computes the intersection of the types x and y.
+// Note: A incomming nil type stands for the top type. A top
+// type result is returned as nil.
+func intersect(x, y Type) (r Type) {
+ defer func() {
+ if r == theTop {
+ r = nil
+ }
+ }()
+
+ switch {
+ case x == theBottom || y == theBottom:
+ return theBottom
+ case x == nil || x == theTop:
+ return y
+ case y == nil || x == theTop:
+ return x
+ }
+
+ xtypes := unpackType(x)
+ ytypes := unpackType(y)
+ // Compute the list rtypes which includes only
+ // types that are in both xtypes and ytypes.
+ // Quadratic algorithm, but good enough for now.
+ // TODO(gri) fix this
+ var rtypes []Type
+ for _, x := range xtypes {
+ if includes(ytypes, x) {
+ rtypes = append(rtypes, x)
+ }
+ }
+
+ if rtypes == nil {
+ return theBottom
+ }
+ return _NewSum(rtypes)
+}
+
+func sortTypes(list []Type) {
+ sort.Stable(byUniqueTypeName(list))
+}
+
+// byUniqueTypeName named type lists can be sorted by their unique type names.
+type byUniqueTypeName []Type
+
+func (a byUniqueTypeName) Len() int { return len(a) }
+func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
+func (a byUniqueTypeName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
+
+func sortName(t Type) string {
+ if named := asNamed(t); named != nil {
+ return named.obj.Id()
+ }
+ return ""
+}
+
+func sortMethods(list []*Func) {
+ sort.Sort(byUniqueMethodName(list))
+}
+
+func assertSortedMethods(list []*Func) {
+ if !debug {
+ panic("internal error: assertSortedMethods called outside debug mode")
+ }
+ if !sort.IsSorted(byUniqueMethodName(list)) {
+ panic("internal error: methods not sorted")
+ }
+}
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
+func (a byUniqueMethodName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
"go/constant"
"go/internal/typeparams"
"go/token"
- "sort"
"strconv"
"strings"
)
return true
}
-func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
- var tlist *ast.Ident // "type" name of first entry in a type list declaration
- var types []ast.Expr
- for _, f := range iface.Methods.List {
- if len(f.Names) > 0 {
- // We have a method with name f.Names[0], or a type
- // of a type list (name.Name == "type").
- // (The parser ensures that there's only one method
- // and we don't care if a constructed AST has more.)
- name := f.Names[0]
- if name.Name == "_" {
- check.errorf(name, _BlankIfaceMethod, "invalid method name _")
- continue // ignore
- }
-
- if name.Name == "type" {
- // Always collect all type list entries, even from
- // different type lists, under the assumption that
- // the author intended to include all types.
- types = append(types, f.Type)
- if tlist != nil && tlist != name {
- check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
- }
- tlist = name
- continue
- }
-
- typ := check.typ(f.Type)
- sig, _ := typ.(*Signature)
- if sig == nil {
- if typ != Typ[Invalid] {
- check.invalidAST(f.Type, "%s is not a method signature", typ)
- }
- continue // ignore
- }
-
- // Always type-check method type parameters but complain if they are not enabled.
- // (This extra check is needed here because interface method signatures don't have
- // a receiver specification.)
- if sig.tparams != nil {
- var at positioner = f.Type
- if tparams := typeparams.Get(f.Type); tparams != nil {
- at = tparams
- }
- check.errorf(at, _Todo, "methods cannot have type parameters")
- }
-
- // use named receiver type if available (for better error messages)
- var recvTyp Type = ityp
- if def != nil {
- recvTyp = def
- }
- sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
-
- m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
- check.recordDef(name, m)
- ityp.methods = append(ityp.methods, m)
- } else {
- // We have an embedded type. completeInterface will
- // eventually verify that we have an interface.
- ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
- check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
- }
- }
-
- // type constraints
- ityp.types = _NewSum(check.collectTypeConstraints(iface.Pos(), types))
-
- if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
- // empty interface
- ityp.allMethods = markComplete
- return
- }
-
- // sort for API stability
- sortMethods(ityp.methods)
- sortTypes(ityp.embeddeds)
-
- check.later(func() { check.completeInterface(iface.Pos(), ityp) })
-}
-
-func (check *Checker) completeInterface(pos token.Pos, ityp *Interface) {
- if ityp.allMethods != nil {
- return
- }
-
- // completeInterface may be called via the LookupFieldOrMethod,
- // MissingMethod, Identical, or IdenticalIgnoreTags external API
- // in which case check will be nil. In this case, type-checking
- // must be finished and all interfaces should have been completed.
- if check == nil {
- panic("internal error: incomplete interface")
- }
-
- if trace {
- // Types don't generally have position information.
- // If we don't have a valid pos provided, try to use
- // one close enough.
- if !pos.IsValid() && len(ityp.methods) > 0 {
- pos = ityp.methods[0].pos
- }
-
- check.trace(pos, "complete %s", ityp)
- check.indent++
- defer func() {
- check.indent--
- check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
- }()
- }
-
- // An infinitely expanding interface (due to a cycle) is detected
- // elsewhere (Checker.validType), so here we simply assume we only
- // have valid interfaces. Mark the interface as complete to avoid
- // infinite recursion if the validType check occurs later for some
- // reason.
- ityp.allMethods = markComplete
-
- // Methods of embedded interfaces are collected unchanged; i.e., the identity
- // of a method I.m's Func Object of an interface I is the same as that of
- // the method m in an interface that embeds interface I. On the other hand,
- // if a method is embedded via multiple overlapping embedded interfaces, we
- // don't provide a guarantee which "original m" got chosen for the embedding
- // interface. See also issue #34421.
- //
- // If we don't care to provide this identity guarantee anymore, instead of
- // reusing the original method in embeddings, we can clone the method's Func
- // Object and give it the position of a corresponding embedded interface. Then
- // we can get rid of the mpos map below and simply use the cloned method's
- // position.
-
- var seen objset
- var methods []*Func
- mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
- addMethod := func(pos token.Pos, m *Func, explicit bool) {
- switch other := seen.insert(m); {
- case other == nil:
- methods = append(methods, m)
- mpos[m] = pos
- case explicit:
- check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
- check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
- default:
- // We have a duplicate method name in an embedded (not explicitly declared) method.
- // Check method signatures after all types are computed (issue #33656).
- // If we're pre-go1.14 (overlapping embeddings are not permitted), report that
- // error here as well (even though we could do it eagerly) because it's the same
- // error message.
- check.later(func() {
- if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
- check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
- check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
- }
- })
- }
- }
-
- for _, m := range ityp.methods {
- addMethod(m.pos, m, true)
- }
-
- // collect types
- allTypes := ityp.types
-
- posList := check.posMap[ityp]
- for i, typ := range ityp.embeddeds {
- pos := posList[i] // embedding position
- utyp := under(typ)
- etyp := asInterface(utyp)
- if etyp == nil {
- if utyp != Typ[Invalid] {
- var format string
- if _, ok := utyp.(*_TypeParam); ok {
- format = "%s is a type parameter, not an interface"
- } else {
- format = "%s is not an interface"
- }
- // TODO: correct error code.
- check.errorf(atPos(pos), _InvalidIfaceEmbed, format, typ)
- }
- continue
- }
- check.completeInterface(pos, etyp)
- for _, m := range etyp.allMethods {
- addMethod(pos, m, false) // use embedding position pos rather than m.pos
- }
- allTypes = intersect(allTypes, etyp.allTypes)
- }
-
- if methods != nil {
- sort.Sort(byUniqueMethodName(methods))
- ityp.allMethods = methods
- }
- ityp.allTypes = allTypes
-}
-
-// intersect computes the intersection of the types x and y.
-// Note: A incomming nil type stands for the top type. A top
-// type result is returned as nil.
-func intersect(x, y Type) (r Type) {
- defer func() {
- if r == theTop {
- r = nil
- }
- }()
-
- switch {
- case x == theBottom || y == theBottom:
- return theBottom
- case x == nil || x == theTop:
- return y
- case y == nil || x == theTop:
- return x
- }
-
- xtypes := unpackType(x)
- ytypes := unpackType(y)
- // Compute the list rtypes which includes only
- // types that are in both xtypes and ytypes.
- // Quadratic algorithm, but good enough for now.
- // TODO(gri) fix this
- var rtypes []Type
- for _, x := range xtypes {
- if includes(ytypes, x) {
- rtypes = append(rtypes, x)
- }
- }
-
- if rtypes == nil {
- return theBottom
- }
- return _NewSum(rtypes)
-}
-
-func sortTypes(list []Type) {
- sort.Stable(byUniqueTypeName(list))
-}
-
-// byUniqueTypeName named type lists can be sorted by their unique type names.
-type byUniqueTypeName []Type
-
-func (a byUniqueTypeName) Len() int { return len(a) }
-func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
-func (a byUniqueTypeName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
-
-func sortName(t Type) string {
- if named := asNamed(t); named != nil {
- return named.obj.Id()
- }
- return ""
-}
-
-func sortMethods(list []*Func) {
- sort.Sort(byUniqueMethodName(list))
-}
-
-func assertSortedMethods(list []*Func) {
- if !debug {
- panic("internal error: assertSortedMethods called outside debug mode")
- }
- if !sort.IsSorted(byUniqueMethodName(list)) {
- panic("internal error: methods not sorted")
- }
-}
-
-// byUniqueMethodName method lists can be sorted by their unique method names.
-type byUniqueMethodName []*Func
-
-func (a byUniqueMethodName) Len() int { return len(a) }
-func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
-func (a byUniqueMethodName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
-
func (check *Checker) tag(t *ast.BasicLit) string {
if t != nil {
if t.Kind == token.STRING {
}
return nil // invalid embedded field
}
-
-func (check *Checker) collectTypeConstraints(pos token.Pos, types []ast.Expr) []Type {
- list := make([]Type, 0, len(types)) // assume all types are correct
- for _, texpr := range types {
- if texpr == nil {
- check.invalidAST(atPos(pos), "missing type constraint")
- continue
- }
- list = append(list, check.varType(texpr))
- }
-
- // Ensure that each type is only present once in the type list. Types may be
- // interfaces, which may not be complete yet. It's ok to do this check at the
- // end because it's not a requirement for correctness of the code.
- // Note: This is a quadratic algorithm, but type lists tend to be short.
- check.later(func() {
- for i, t := range list {
- if t := asInterface(t); t != nil {
- check.completeInterface(types[i].Pos(), t)
- }
- if includes(list[:i], t) {
- check.softErrorf(types[i], _Todo, "duplicate type %s in type list", t)
- }
- }
- })
-
- return list
-}
-
-// includes reports whether typ is in list.
-func includes(list []Type, typ Type) bool {
- for _, e := range list {
- if Identical(typ, e) {
- return true
- }
- }
- return false
-}