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[dev.typeparams] cmd/compile/internal/types2: remove disabled code related to type lists

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Earlier (contract-based) versions of the generics design restricted the
kind of types that could be used in a type list - the current design does
not have these restrictions anymore. Remove the respective checking code.

Change-Id: Ia333f7aa8a9c31a92c08acbd5cadba3532a455b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/281546
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-01-05 12:33:11 -08:00
parent 196102d046
commit 9546596d77
1 changed files with 1 additions and 68 deletions
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69
src/cmd/compile/internal/types2/typexpr.go
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@ -1192,18 +1192,7 @@ func (check *Checker) collectTypeConstraints(pos syntax.Pos, types []syntax.Expr
check.invalidASTf(pos, "missing type constraint")
continue
}
typ := check.varType(texpr)
// A type constraint may be a predeclared type or a
// composite type composed of only predeclared types.
// TODO(gri) If we enable this again it also must run
// at the end.
const restricted = false
var why string
if restricted && !check.typeConstraint(typ, &why) {
check.errorf(texpr, "invalid type constraint %s (%s)", typ, why)
continue
}
list = append(list, typ)
list = append(list, check.varType(texpr))
}
// Ensure that each type is only present once in the type list. Types may be
@ -1234,62 +1223,6 @@ func includes(list []Type, typ Type) bool {
return false
}
// typeConstraint checks that typ may be used in a type list.
// For now this just checks for the absence of defined (*Named) types.
func (check *Checker) typeConstraint(typ Type, why *string) bool {
switch t := typ.(type) {
case *Basic:
// ok
case *Array:
return check.typeConstraint(t.elem, why)
case *Slice:
return check.typeConstraint(t.elem, why)
case *Struct:
for _, f := range t.fields {
if !check.typeConstraint(f.typ, why) {
return false
}
}
case *Pointer:
return check.typeConstraint(t.base, why)
case *Tuple:
if t == nil {
return true
}
for _, v := range t.vars {
if !check.typeConstraint(v.typ, why) {
return false
}
}
case *Signature:
if len(t.tparams) != 0 {
panic("type parameter in function type")
}
return (t.recv == nil || check.typeConstraint(t.recv.typ, why)) &&
check.typeConstraint(t.params, why) &&
check.typeConstraint(t.results, why)
case *Interface:
t.assertCompleteness()
for _, m := range t.allMethods {
if !check.typeConstraint(m.typ, why) {
return false
}
}
case *Map:
return check.typeConstraint(t.key, why) && check.typeConstraint(t.elem, why)
case *Chan:
return check.typeConstraint(t.elem, why)
case *Named:
*why = check.sprintf("contains defined type %s", t)
return false
case *TypeParam:
// ok, e.g.: func f (type T interface { type T }) ()
default:
unreachable()
}
return true
}
func ptrBase(x *syntax.Operation) syntax.Expr {
if x.Op == syntax.Mul && x.Y == nil {
return x.X