From d6753fd491c101e71f5e86d87b44d396828e2deb Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Fri, 23 Jul 2021 10:26:07 -0700 Subject: [PATCH] [dev.typeparams] cmd/compile/internal/types2: implement TypeParam.Constraint Change-Id: I95a96f9dbd199cee3a4be8f42cd64e7f44ba5e5b Reviewed-on: https://go-review.googlesource.com/c/go/+/336989 Trust: Robert Griesemer Run-TryBot: Robert Griesemer Reviewed-by: Robert Findley TryBot-Result: Go Bot --- src/cmd/compile/internal/types2/typeparam.go | 32 ++++++++++++-------- 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/src/cmd/compile/internal/types2/typeparam.go b/src/cmd/compile/internal/types2/typeparam.go index b73b4edf79..0aca227c0a 100644 --- a/src/cmd/compile/internal/types2/typeparam.go +++ b/src/cmd/compile/internal/types2/typeparam.go @@ -53,20 +53,28 @@ func (t *TypeParam) SetId(id uint64) { t.id = id } +// Constraint returns the type constraint specified for t. +func (t *TypeParam) Constraint() Type { + // compute the type set if possible (we may not have an interface) + if iface, _ := under(t.bound).(*Interface); iface != nil { + // use the type bound position if we have one + pos := nopos + if n, _ := t.bound.(*Named); n != nil { + pos = n.obj.pos + } + computeTypeSet(t.check, pos, iface) + } + return t.bound +} + +// Bound returns the underlying type of the type parameter's +// constraint. +// Deprecated for external use. Use Constraint instead. func (t *TypeParam) Bound() *Interface { - // we may not have an interface (error reported elsewhere) - iface, _ := under(t.bound).(*Interface) - if iface == nil { - return &emptyInterface + if iface, _ := under(t.Constraint()).(*Interface); iface != nil { + return iface } - // use the type bound position if we have one - pos := nopos - if n, _ := t.bound.(*Named); n != nil { - pos = n.obj.pos - } - // TODO(gri) switch this to an unexported method on Checker. - computeTypeSet(t.check, pos, iface) - return iface + return &emptyInterface } func (t *TypeParam) SetBound(bound Type) {