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[dev.typeparams] go/types: move methods on *Named into named.go
This is a port of CL 333671 to go/types. Change-Id: Ic2f66b49f1db68fb93d5095131733e99a37b9cbf Reviewed-on: https://go-review.googlesource.com/c/go/+/335074 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
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@ -569,102 +569,6 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
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check.initVars(lhs, []ast.Expr{init}, token.NoPos)
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}
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// under returns the expanded underlying type of n0; possibly by following
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// forward chains of named types. If an underlying type is found, resolve
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// the chain by setting the underlying type for each defined type in the
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// chain before returning it. If no underlying type is found or a cycle
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// is detected, the result is Typ[Invalid]. If a cycle is detected and
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// n0.check != nil, the cycle is reported.
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func (n0 *Named) under() Type {
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u := n0.Underlying()
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if u == Typ[Invalid] {
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return u
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}
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// If the underlying type of a defined type is not a defined
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// (incl. instance) type, then that is the desired underlying
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// type.
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switch u.(type) {
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case nil:
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return Typ[Invalid]
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default:
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// common case
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return u
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case *Named, *instance:
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// handled below
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}
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if n0.check == nil {
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panic("internal error: Named.check == nil but type is incomplete")
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}
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// Invariant: after this point n0 as well as any named types in its
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// underlying chain should be set up when this function exits.
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check := n0.check
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// If we can't expand u at this point, it is invalid.
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n := asNamed(u)
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if n == nil {
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n0.underlying = Typ[Invalid]
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return n0.underlying
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}
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// Otherwise, follow the forward chain.
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seen := map[*Named]int{n0: 0}
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path := []Object{n0.obj}
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for {
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u = n.Underlying()
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if u == nil {
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u = Typ[Invalid]
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break
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}
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var n1 *Named
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switch u1 := u.(type) {
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case *Named:
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n1 = u1
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case *instance:
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n1, _ = u1.expand().(*Named)
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if n1 == nil {
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u = Typ[Invalid]
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}
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}
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if n1 == nil {
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break // end of chain
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}
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seen[n] = len(seen)
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path = append(path, n.obj)
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n = n1
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if i, ok := seen[n]; ok {
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// cycle
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check.cycleError(path[i:])
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u = Typ[Invalid]
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break
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}
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}
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for n := range seen {
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// We should never have to update the underlying type of an imported type;
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// those underlying types should have been resolved during the import.
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// Also, doing so would lead to a race condition (was issue #31749).
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// Do this check always, not just in debug mode (it's cheap).
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if n.obj.pkg != check.pkg {
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panic("internal error: imported type with unresolved underlying type")
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}
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n.underlying = u
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}
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return u
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}
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func (n *Named) setUnderlying(typ Type) {
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if n != nil {
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n.underlying = typ
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}
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}
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func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
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assert(obj.typ == nil)
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@ -142,3 +142,102 @@ func (t *Named) AddMethod(m *Func) {
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func (t *Named) Underlying() Type { return t.expand().underlying }
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func (t *Named) String() string { return TypeString(t, nil) }
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// ----------------------------------------------------------------------------
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// Implementation
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// under returns the expanded underlying type of n0; possibly by following
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// forward chains of named types. If an underlying type is found, resolve
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// the chain by setting the underlying type for each defined type in the
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// chain before returning it. If no underlying type is found or a cycle
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// is detected, the result is Typ[Invalid]. If a cycle is detected and
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// n0.check != nil, the cycle is reported.
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func (n0 *Named) under() Type {
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u := n0.Underlying()
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if u == Typ[Invalid] {
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return u
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}
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// If the underlying type of a defined type is not a defined
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// (incl. instance) type, then that is the desired underlying
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// type.
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switch u.(type) {
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case nil:
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return Typ[Invalid]
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default:
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// common case
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return u
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case *Named, *instance:
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// handled below
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}
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if n0.check == nil {
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panic("internal error: Named.check == nil but type is incomplete")
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}
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// Invariant: after this point n0 as well as any named types in its
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// underlying chain should be set up when this function exits.
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check := n0.check
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// If we can't expand u at this point, it is invalid.
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n := asNamed(u)
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if n == nil {
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n0.underlying = Typ[Invalid]
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return n0.underlying
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}
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// Otherwise, follow the forward chain.
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seen := map[*Named]int{n0: 0}
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path := []Object{n0.obj}
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for {
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u = n.Underlying()
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if u == nil {
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u = Typ[Invalid]
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break
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}
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var n1 *Named
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switch u1 := u.(type) {
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case *Named:
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n1 = u1
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case *instance:
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n1, _ = u1.expand().(*Named)
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if n1 == nil {
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u = Typ[Invalid]
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}
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}
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if n1 == nil {
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break // end of chain
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}
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seen[n] = len(seen)
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path = append(path, n.obj)
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n = n1
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if i, ok := seen[n]; ok {
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// cycle
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check.cycleError(path[i:])
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u = Typ[Invalid]
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break
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}
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}
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for n := range seen {
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// We should never have to update the underlying type of an imported type;
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// those underlying types should have been resolved during the import.
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// Also, doing so would lead to a race condition (was issue #31749).
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// Do this check always, not just in debug mode (it's cheap).
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if n.obj.pkg != check.pkg {
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panic("internal error: imported type with unresolved underlying type")
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}
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n.underlying = u
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}
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return u
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}
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func (n *Named) setUnderlying(typ Type) {
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if n != nil {
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n.underlying = typ
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}
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}
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