package types2
+// isValid reports whether t is a valid type.
+func isValid(t Type) bool { return _Unalias(t) != Typ[Invalid] }
+
// The isX predicates below report whether t is an X.
// If t is a type parameter the result is false; i.e.,
// these predicates don't look inside a type parameter.
// The allX predicates below report whether t is an X.
// If t is a type parameter the result is true if isX is true
// for all specified types of the type parameter's type set.
-// allX is an optimized version of isX(structure(t)) (which
+// allX is an optimized version of isX(coreType(t)) (which
// is the same as underIs(t, isX)).
func allBoolean(t Type) bool { return allBasic(t, IsBoolean) }
// allBasic reports whether under(t) is a basic type with the specified info.
// If t is a type parameter, the result is true if isBasic(t, info) is true
// for all specific types of the type parameter's type set.
-// allBasic(t, info) is an optimized version of isBasic(structure(t), info).
+// allBasic(t, info) is an optimized version of isBasic(coreType(t), info).
func allBasic(t Type, info BasicInfo) bool {
- switch u := under(t).(type) {
- case *Basic:
- return u.info&info != 0
- case *TypeParam:
- return u.is(func(t *term) bool { return t != nil && isBasic(t.typ, info) })
+ if tpar, _ := _Unalias(t).(*TypeParam); tpar != nil {
+ return tpar.is(func(t *term) bool { return t != nil && isBasic(t.typ, info) })
}
- return false
+ return isBasic(t, info)
}
// hasName reports whether t has a name. This includes
// predeclared types, defined types, and type parameters.
// hasName may be called with types that are not fully set up.
func hasName(t Type) bool {
- switch t.(type) {
+ switch _Unalias(t).(type) {
case *Basic, *Named, *TypeParam:
return true
}
return false
}
+// isTypeLit reports whether t is a type literal.
+// This includes all non-defined types, but also basic types.
+// isTypeLit may be called with types that are not fully set up.
+func isTypeLit(t Type) bool {
+ switch _Unalias(t).(type) {
+ case *Named, *TypeParam:
+ return false
+ }
+ return true
+}
+
// isTyped reports whether t is typed; i.e., not an untyped
// constant or boolean. isTyped may be called with types that
// are not fully set up.
func isTyped(t Type) bool {
- // isTyped is called with types that are not fully
- // set up. Must not call asBasic()!
+ // Alias or Named types cannot denote untyped types,
+ // thus we don't need to call _Unalias or under
+ // (which would be unsafe to do for types that are
+ // not fully set up).
b, _ := t.(*Basic)
return b == nil || b.info&IsUntyped == 0
}
// IsInterface reports whether t is an interface type.
func IsInterface(t Type) bool {
- return asInterface(t) != nil
+ _, ok := under(t).(*Interface)
+ return ok
+}
+
+// isNonTypeParamInterface reports whether t is an interface type but not a type parameter.
+func isNonTypeParamInterface(t Type) bool {
+ return !isTypeParam(t) && IsInterface(t)
}
// isTypeParam reports whether t is a type parameter.
func isTypeParam(t Type) bool {
- _, ok := under(t).(*TypeParam)
+ _, ok := _Unalias(t).(*TypeParam)
return ok
}
+// hasEmptyTypeset reports whether t is a type parameter with an empty type set.
+// The function does not force the computation of the type set and so is safe to
+// use anywhere, but it may report a false negative if the type set has not been
+// computed yet.
+func hasEmptyTypeset(t Type) bool {
+ if tpar, _ := _Unalias(t).(*TypeParam); tpar != nil && tpar.bound != nil {
+ iface, _ := safeUnderlying(tpar.bound).(*Interface)
+ return iface != nil && iface.tset != nil && iface.tset.IsEmpty()
+ }
+ return false
+}
+
// isGeneric reports whether a type is a generic, uninstantiated type
// (generic signatures are not included).
// TODO(gri) should we include signatures or assert that they are not present?
func isGeneric(t Type) bool {
// A parameterized type is only generic if it doesn't have an instantiation already.
- named, _ := t.(*Named)
- return named != nil && named.obj != nil && named.targs == nil && named.TypeParams() != nil
+ named := asNamed(t)
+ return named != nil && named.obj != nil && named.inst == nil && named.TypeParams().Len() > 0
}
// Comparable reports whether values of type T are comparable.
func Comparable(T Type) bool {
- return comparable(T, nil)
+ return comparable(T, true, nil, nil)
}
-func comparable(T Type, seen map[Type]bool) bool {
+// If dynamic is set, non-type parameter interfaces are always comparable.
+// If reportf != nil, it may be used to report why T is not comparable.
+func comparable(T Type, dynamic bool, seen map[Type]bool, reportf func(string, ...interface{})) bool {
if seen[T] {
return true
}
// assume invalid types to be comparable
// to avoid follow-up errors
return t.kind != UntypedNil
- case *Pointer, *Interface, *Chan:
+ case *Pointer, *Chan:
return true
case *Struct:
for _, f := range t.fields {
- if !comparable(f.typ, seen) {
+ if !comparable(f.typ, dynamic, seen, nil) {
+ if reportf != nil {
+ reportf("struct containing %s cannot be compared", f.typ)
+ }
return false
}
}
return true
case *Array:
- return comparable(t.elem, seen)
- case *TypeParam:
- return t.iface().IsComparable()
+ if !comparable(t.elem, dynamic, seen, nil) {
+ if reportf != nil {
+ reportf("%s cannot be compared", t)
+ }
+ return false
+ }
+ return true
+ case *Interface:
+ if dynamic && !isTypeParam(T) || t.typeSet().IsComparable(seen) {
+ return true
+ }
+ if reportf != nil {
+ if t.typeSet().IsEmpty() {
+ reportf("empty type set")
+ } else {
+ reportf("incomparable types in type set")
+ }
+ }
+ // fallthrough
}
return false
}
switch u := under(t).(type) {
case *Basic:
return u.kind == UnsafePointer
- case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
+ case *Slice, *Pointer, *Signature, *Map, *Chan:
return true
- case *TypeParam:
- return u.underIs(hasNil)
+ case *Interface:
+ return !isTypeParam(t) || u.typeSet().underIs(func(u Type) bool {
+ return u != nil && hasNil(u)
+ })
}
return false
}
return p.x == q.x && p.y == q.y || p.x == q.y && p.y == q.x
}
+// A comparer is used to compare types.
+type comparer struct {
+ ignoreTags bool // if set, identical ignores struct tags
+ ignoreInvalids bool // if set, identical treats an invalid type as identical to any type
+}
+
// For changes to this code the corresponding changes should be made to unifier.nify.
-func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
+func (c *comparer) identical(x, y Type, p *ifacePair) bool {
+ x = _Unalias(x)
+ y = _Unalias(y)
+
if x == y {
return true
}
+ if c.ignoreInvalids && (!isValid(x) || !isValid(y)) {
+ return true
+ }
+
switch x := x.(type) {
case *Basic:
// Basic types are singletons except for the rune and byte
if y, ok := y.(*Array); ok {
// If one or both array lengths are unknown (< 0) due to some error,
// assume they are the same to avoid spurious follow-on errors.
- return (x.len < 0 || y.len < 0 || x.len == y.len) && identical(x.elem, y.elem, cmpTags, p)
+ return (x.len < 0 || y.len < 0 || x.len == y.len) && c.identical(x.elem, y.elem, p)
}
case *Slice:
// Two slice types are identical if they have identical element types.
if y, ok := y.(*Slice); ok {
- return identical(x.elem, y.elem, cmpTags, p)
+ return c.identical(x.elem, y.elem, p)
}
case *Struct:
for i, f := range x.fields {
g := y.fields[i]
if f.embedded != g.embedded ||
- cmpTags && x.Tag(i) != y.Tag(i) ||
+ !c.ignoreTags && x.Tag(i) != y.Tag(i) ||
!f.sameId(g.pkg, g.name) ||
- !identical(f.typ, g.typ, cmpTags, p) {
+ !c.identical(f.typ, g.typ, p) {
return false
}
}
case *Pointer:
// Two pointer types are identical if they have identical base types.
if y, ok := y.(*Pointer); ok {
- return identical(x.base, y.base, cmpTags, p)
+ return c.identical(x.base, y.base, p)
}
case *Tuple:
if x != nil {
for i, v := range x.vars {
w := y.vars[i]
- if !identical(v.typ, w.typ, cmpTags, p) {
+ if !c.identical(v.typ, w.typ, p) {
return false
}
}
}
case *Signature:
- // Two function types are identical if they have the same number of parameters
- // and result values, corresponding parameter and result types are identical,
- // and either both functions are variadic or neither is. Parameter and result
- // names are not required to match.
- // Generic functions must also have matching type parameter lists, but for the
- // parameter names.
- if y, ok := y.(*Signature); ok {
- return x.variadic == y.variadic &&
- identicalTParams(x.TypeParams().list(), y.TypeParams().list(), cmpTags, p) &&
- identical(x.params, y.params, cmpTags, p) &&
- identical(x.results, y.results, cmpTags, p)
+ y, _ := y.(*Signature)
+ if y == nil {
+ return false
+ }
+
+ // Two function types are identical if they have the same number of
+ // parameters and result values, corresponding parameter and result types
+ // are identical, and either both functions are variadic or neither is.
+ // Parameter and result names are not required to match, and type
+ // parameters are considered identical modulo renaming.
+
+ if x.TypeParams().Len() != y.TypeParams().Len() {
+ return false
}
+ // In the case of generic signatures, we will substitute in yparams and
+ // yresults.
+ yparams := y.params
+ yresults := y.results
+
+ if x.TypeParams().Len() > 0 {
+ // We must ignore type parameter names when comparing x and y. The
+ // easiest way to do this is to substitute x's type parameters for y's.
+ xtparams := x.TypeParams().list()
+ ytparams := y.TypeParams().list()
+
+ var targs []Type
+ for i := range xtparams {
+ targs = append(targs, x.TypeParams().At(i))
+ }
+ smap := makeSubstMap(ytparams, targs)
+
+ var check *Checker // ok to call subst on a nil *Checker
+ ctxt := NewContext() // need a non-nil Context for the substitution below
+
+ // Constraints must be pair-wise identical, after substitution.
+ for i, xtparam := range xtparams {
+ ybound := check.subst(nopos, ytparams[i].bound, smap, nil, ctxt)
+ if !c.identical(xtparam.bound, ybound, p) {
+ return false
+ }
+ }
+
+ yparams = check.subst(nopos, y.params, smap, nil, ctxt).(*Tuple)
+ yresults = check.subst(nopos, y.results, smap, nil, ctxt).(*Tuple)
+ }
+
+ return x.variadic == y.variadic &&
+ c.identical(x.params, yparams, p) &&
+ c.identical(x.results, yresults, p)
+
case *Union:
if y, _ := y.(*Union); y != nil {
- xset := computeUnionTypeSet(nil, nopos, x)
- yset := computeUnionTypeSet(nil, nopos, y)
+ // TODO(rfindley): can this be reached during type checking? If so,
+ // consider passing a type set map.
+ unionSets := make(map[*Union]*_TypeSet)
+ xset := computeUnionTypeSet(nil, unionSets, nopos, x)
+ yset := computeUnionTypeSet(nil, unionSets, nopos, y)
return xset.terms.equal(yset.terms)
}
if y, ok := y.(*Interface); ok {
xset := x.typeSet()
yset := y.typeSet()
+ if xset.comparable != yset.comparable {
+ return false
+ }
if !xset.terms.equal(yset.terms) {
return false
}
}
for i, f := range a {
g := b[i]
- if f.Id() != g.Id() || !identical(f.typ, g.typ, cmpTags, q) {
+ if f.Id() != g.Id() || !c.identical(f.typ, g.typ, q) {
return false
}
}
case *Map:
// Two map types are identical if they have identical key and value types.
if y, ok := y.(*Map); ok {
- return identical(x.key, y.key, cmpTags, p) && identical(x.elem, y.elem, cmpTags, p)
+ return c.identical(x.key, y.key, p) && c.identical(x.elem, y.elem, p)
}
case *Chan:
// Two channel types are identical if they have identical value types
// and the same direction.
if y, ok := y.(*Chan); ok {
- return x.dir == y.dir && identical(x.elem, y.elem, cmpTags, p)
+ return x.dir == y.dir && c.identical(x.elem, y.elem, p)
}
case *Named:
// Two named types are identical if their type names originate
- // in the same type declaration.
- if y, ok := y.(*Named); ok {
+ // in the same type declaration; if they are instantiated they
+ // must have identical type argument lists.
+ if y := asNamed(y); y != nil {
+ // check type arguments before origins to match unifier
+ // (for correct source code we need to do all checks so
+ // order doesn't matter)
xargs := x.TypeArgs().list()
yargs := y.TypeArgs().list()
-
if len(xargs) != len(yargs) {
return false
}
-
- if len(xargs) > 0 {
- // Instances are identical if their original type and type arguments
- // are identical.
- if !Identical(x.orig, y.orig) {
+ for i, xarg := range xargs {
+ if !Identical(xarg, yargs[i]) {
return false
}
- for i, xa := range xargs {
- if !Identical(xa, yargs[i]) {
- return false
- }
- }
- return true
}
-
- // TODO(gri) Why is x == y not sufficient? And if it is,
- // we can just return false here because x == y
- // is caught in the very beginning of this function.
- return x.obj == y.obj
+ return identicalOrigin(x, y)
}
case *TypeParam:
return false
}
-func identicalTParams(x, y []*TypeParam, cmpTags bool, p *ifacePair) bool {
- if len(x) != len(y) {
+// identicalOrigin reports whether x and y originated in the same declaration.
+func identicalOrigin(x, y *Named) bool {
+ // TODO(gri) is this correct?
+ return x.Origin().obj == y.Origin().obj
+}
+
+// identicalInstance reports if two type instantiations are identical.
+// Instantiations are identical if their origin and type arguments are
+// identical.
+func identicalInstance(xorig Type, xargs []Type, yorig Type, yargs []Type) bool {
+ if len(xargs) != len(yargs) {
return false
}
- for i, x := range x {
- y := y[i]
- if !identical(x.bound, y.bound, cmpTags, p) {
+
+ for i, xa := range xargs {
+ if !Identical(xa, yargs[i]) {
return false
}
}
- return true
+
+ return Identical(xorig, yorig)
}
// Default returns the default "typed" type for an "untyped" type;
// it returns the incoming type for all other types. The default type
// for untyped nil is untyped nil.
func Default(t Type) Type {
- if t, ok := t.(*Basic); ok {
+ if t, ok := _Unalias(t).(*Basic); ok {
switch t.kind {
case UntypedBool:
return Typ[Bool]
}
return t
}
+
+// maxType returns the "largest" type that encompasses both x and y.
+// If x and y are different untyped numeric types, the result is the type of x or y
+// that appears later in this list: integer, rune, floating-point, complex.
+// Otherwise, if x != y, the result is nil.
+func maxType(x, y Type) Type {
+ // We only care about untyped types (for now), so == is good enough.
+ // TODO(gri) investigate generalizing this function to simplify code elsewhere
+ if x == y {
+ return x
+ }
+ if isUntyped(x) && isUntyped(y) && isNumeric(x) && isNumeric(y) {
+ // untyped types are basic types
+ if x.(*Basic).kind > y.(*Basic).kind {
+ return x
+ }
+ return y
+ }
+ return nil
+}
+
+// clone makes a "flat copy" of *p and returns a pointer to the copy.
+func clone[P *T, T any](p P) P {
+ c := *p
+ return &c
+}