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[dev.typeparams] cmd/compile/internal/types2: move methods on *Named into named.go (cleanup)

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No other code changes except for an additional comment.

Change-Id: Ica3cea446c6c88f4f81a86d77b289a0b54b1e76f
Reviewed-on: https://go-review.googlesource.com/c/go/+/333671
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-07-09 16:02:45 -07:00
parent d0324eb8fb
commit e5faa8d84b
2 changed files with 99 additions and 96 deletions
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96
src/cmd/compile/internal/types2/decl.go
View File

@ -515,102 +515,6 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init syntax.Expr) {
check.initVars(lhs, []syntax.Expr{init}, nopos)
}
// under returns the expanded underlying type of n0; possibly by following
// forward chains of named types. If an underlying type is found, resolve
// the chain by setting the underlying type for each defined type in the
// chain before returning it. If no underlying type is found or a cycle
// is detected, the result is Typ[Invalid]. If a cycle is detected and
// n0.check != nil, the cycle is reported.
func (n0 *Named) under() Type {
u := n0.Underlying()
if u == Typ[Invalid] {
return u
}
// If the underlying type of a defined type is not a defined
// (incl. instance) type, then that is the desired underlying
// type.
switch u.(type) {
case nil:
return Typ[Invalid]
default:
// common case
return u
case *Named, *instance:
// handled below
}
if n0.check == nil {
panic("internal error: Named.check == nil but type is incomplete")
}
// Invariant: after this point n0 as well as any named types in its
// underlying chain should be set up when this function exits.
check := n0.check
// If we can't expand u at this point, it is invalid.
n := asNamed(u)
if n == nil {
n0.underlying = Typ[Invalid]
return n0.underlying
}
// Otherwise, follow the forward chain.
seen := map[*Named]int{n0: 0}
path := []Object{n0.obj}
for {
u = n.Underlying()
if u == nil {
u = Typ[Invalid]
break
}
var n1 *Named
switch u1 := u.(type) {
case *Named:
n1 = u1
case *instance:
n1, _ = u1.expand().(*Named)
if n1 == nil {
u = Typ[Invalid]
}
}
if n1 == nil {
break // end of chain
}
seen[n] = len(seen)
path = append(path, n.obj)
n = n1
if i, ok := seen[n]; ok {
// cycle
check.cycleError(path[i:])
u = Typ[Invalid]
break
}
}
for n := range seen {
// We should never have to update the underlying type of an imported type;
// those underlying types should have been resolved during the import.
// Also, doing so would lead to a race condition (was issue #31749).
// Do this check always, not just in debug mode (it's cheap).
if n.obj.pkg != check.pkg {
panic("internal error: imported type with unresolved underlying type")
}
n.underlying = u
}
return u
}
func (n *Named) setUnderlying(typ Type) {
if n != nil {
n.underlying = typ
}
}
func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named) {
assert(obj.typ == nil)

99
src/cmd/compile/internal/types2/named.go
View File

@ -142,3 +142,102 @@ func (t *Named) AddMethod(m *Func) {
func (t *Named) Underlying() Type { return t.expand().underlying }
func (t *Named) String() string { return TypeString(t, nil) }
// ----------------------------------------------------------------------------
// Implementation
// under returns the expanded underlying type of n0; possibly by following
// forward chains of named types. If an underlying type is found, resolve
// the chain by setting the underlying type for each defined type in the
// chain before returning it. If no underlying type is found or a cycle
// is detected, the result is Typ[Invalid]. If a cycle is detected and
// n0.check != nil, the cycle is reported.
func (n0 *Named) under() Type {
u := n0.Underlying()
if u == Typ[Invalid] {
return u
}
// If the underlying type of a defined type is not a defined
// (incl. instance) type, then that is the desired underlying
// type.
switch u.(type) {
case nil:
return Typ[Invalid]
default:
// common case
return u
case *Named, *instance:
// handled below
}
if n0.check == nil {
panic("internal error: Named.check == nil but type is incomplete")
}
// Invariant: after this point n0 as well as any named types in its
// underlying chain should be set up when this function exits.
check := n0.check
// If we can't expand u at this point, it is invalid.
n := asNamed(u)
if n == nil {
n0.underlying = Typ[Invalid]
return n0.underlying
}
// Otherwise, follow the forward chain.
seen := map[*Named]int{n0: 0}
path := []Object{n0.obj}
for {
u = n.Underlying()
if u == nil {
u = Typ[Invalid]
break
}
var n1 *Named
switch u1 := u.(type) {
case *Named:
n1 = u1
case *instance:
n1, _ = u1.expand().(*Named)
if n1 == nil {
u = Typ[Invalid]
}
}
if n1 == nil {
break // end of chain
}
seen[n] = len(seen)
path = append(path, n.obj)
n = n1
if i, ok := seen[n]; ok {
// cycle
check.cycleError(path[i:])
u = Typ[Invalid]
break
}
}
for n := range seen {
// We should never have to update the underlying type of an imported type;
// those underlying types should have been resolved during the import.
// Also, doing so would lead to a race condition (was issue #31749).
// Do this check always, not just in debug mode (it's cheap).
if n.obj.pkg != check.pkg {
panic("internal error: imported type with unresolved underlying type")
}
n.underlying = u
}
return u
}
func (n *Named) setUnderlying(typ Type) {
if n != nil {
n.underlying = typ
}
}