go/types, types2: introduce _Alias type node

[gostls13.git] / src / go / types / predicates.go

diff --git a/src/go/types/predicates.go b/src/go/types/predicates.go
index 01804c69c51cf3f46f9dcc70a877e1b3ae97fc25..5dc775af8d4c33332a46e7b4365ee0e9bed3b80a 100644 (file)
--- a/src/go/types/predicates.go
+++ b/src/go/types/predicates.go
@@ -9,7 +9,7 @@
 package types
 
 // isValid reports whether t is a valid type.
-func isValid(t Type) bool { return t != Typ[Invalid] }
+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.,
@@ -52,7 +52,7 @@ func allNumericOrString(t Type) bool { return allBasic(t, IsNumeric|IsString) }
 // for all specific types of the type parameter's type set.
 // allBasic(t, info) is an optimized version of isBasic(coreType(t), info).
 func allBasic(t Type, info BasicInfo) bool {
-       if tpar, _ := t.(*TypeParam); tpar != nil {
+       if tpar, _ := _Unalias(t).(*TypeParam); tpar != nil {
                return tpar.is(func(t *term) bool { return t != nil && isBasic(t.typ, info) })
        }
        return isBasic(t, info)
@@ -62,7 +62,7 @@ func allBasic(t Type, info BasicInfo) bool {
 // 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
        }
@@ -73,7 +73,7 @@ func hasName(t Type) bool {
 // 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 t.(type) {
+       switch _Unalias(t).(type) {
        case *Named, *TypeParam:
                return false
        }
@@ -84,8 +84,10 @@ func isTypeLit(t Type) bool {
 // 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 under()!
+       // 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
 }
@@ -108,7 +110,7 @@ func isNonTypeParamInterface(t Type) bool {
 
 // isTypeParam reports whether t is a type parameter.
 func isTypeParam(t Type) bool {
-       _, ok := t.(*TypeParam)
+       _, ok := _Unalias(t).(*TypeParam)
        return ok
 }
 
@@ -117,7 +119,7 @@ func isTypeParam(t Type) bool {
 // 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, _ := t.(*TypeParam); tpar != nil && tpar.bound != nil {
+       if tpar, _ := _Unalias(t).(*TypeParam); tpar != nil && tpar.bound != nil {
                iface, _ := safeUnderlying(tpar.bound).(*Interface)
                return iface != nil && iface.tset != nil && iface.tset.IsEmpty()
        }
@@ -223,6 +225,9 @@ type comparer struct {
 
 // For changes to this code the corresponding changes should be made to unifier.nify.
 func (c *comparer) identical(x, y Type, p *ifacePair) bool {
+       x = _Unalias(x)
+       y = _Unalias(y)
+
        if x == y {
                return true
        }
@@ -497,7 +502,7 @@ func identicalInstance(xorig Type, xargs []Type, yorig Type, yargs []Type) bool
 // 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]