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[dev.typeparams] go/types: eliminate need for unpack and asUnion functions
This is a straightforward port of CL 323355 to go/types, adjusted for the different error reporting API in go/types. Change-Id: I0f9d7ca0e0959e1e214ecd61eb85cc311e6409a2 Reviewed-on: https://go-review.googlesource.com/c/go/+/326679 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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@ -768,14 +768,12 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
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if tp := asTypeParam(x); tp != nil {
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// Test if t satisfies the requirements for the argument
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// type and collect possible result types at the same time.
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// TODO(gri) This needs to consider the ~ information if we
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// have a union type.
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var rtypes []Type
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var tilde []bool
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if !tp.Bound().is(func(x Type) bool {
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if r := f(x); r != nil {
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var tildes []bool
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if !tp.Bound().is(func(typ Type, tilde bool) bool {
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if r := f(typ); r != nil {
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rtypes = append(rtypes, r)
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tilde = append(tilde, true)
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tildes = append(tildes, tilde)
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return true
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}
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return false
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@ -786,7 +784,7 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
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// construct a suitable new type parameter
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tpar := NewTypeName(token.NoPos, nil /* = Universe pkg */, "<type parameter>", nil)
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ptyp := check.newTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
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tsum := newUnion(rtypes, tilde)
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tsum := newUnion(rtypes, tildes)
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ptyp.bound = &Interface{allMethods: markComplete, allTypes: tsum}
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return ptyp
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@ -323,7 +323,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
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return true
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}
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}
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return w.isParameterizedList(unpackType(t.allTypes))
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return w.isParameterized(t.allTypes)
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}
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return t.iterate(func(t *Interface) bool {
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@ -472,11 +472,14 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
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func (check *Checker) structuralType(constraint Type) Type {
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if iface, _ := under(constraint).(*Interface); iface != nil {
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check.completeInterface(token.NoPos, iface)
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types := unpackType(iface.allTypes)
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if len(types) == 1 {
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return types[0]
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if u, _ := iface.allTypes.(*Union); u != nil {
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if u.NumTerms() == 1 {
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// TODO(gri) do we need to respect tilde?
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return u.types[0]
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}
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return nil
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}
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return nil
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return iface.allTypes
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}
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return constraint
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return nil
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}
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@ -198,14 +198,15 @@ func (check *Checker) satisfies(pos token.Pos, targ Type, tpar *_TypeParam, smap
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check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
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return false
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}
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for _, t := range unpackType(targBound.allTypes) {
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if !iface.isSatisfiedBy(t) {
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return iface.is(func(typ Type, tilde bool) bool {
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// TODO(gri) incorporate tilde information!
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if !iface.isSatisfiedBy(typ) {
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// TODO(gri) match this error message with the one below (or vice versa)
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check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, t, iface.allTypes)
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check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, typ, iface.allTypes)
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return false
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}
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}
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return false
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return true
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})
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}
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// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
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@ -266,29 +266,17 @@ type Interface struct {
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obj Object // type declaration defining this interface; or nil (for better error messages)
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}
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// unpack unpacks a type into a list of types.
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// TODO(gri) Try to eliminate the need for this function.
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func unpackType(typ Type) []Type {
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if typ == nil {
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return nil
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}
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if u := asUnion(typ); u != nil {
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return u.types
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}
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return []Type{typ}
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}
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// is reports whether interface t represents types that all satisfy pred.
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func (t *Interface) is(pred func(Type) bool) bool {
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if t.allTypes == nil {
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// is reports whether interface t represents types that all satisfy f.
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func (t *Interface) is(f func(Type, bool) bool) bool {
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switch t := t.allTypes.(type) {
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case nil, *top:
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// TODO(gri) should settle on top or nil to represent this case
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return false // we must have at least one type! (was bug)
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case *Union:
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return t.is(func(typ Type, tilde bool) bool { return f(typ, tilde) })
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default:
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return f(t, false)
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}
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for _, t := range unpackType(t.allTypes) {
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if !pred(t) {
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return false
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}
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}
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return true
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}
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// emptyInterface represents the empty (completed) interface
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@ -824,11 +812,6 @@ func asSignature(t Type) *Signature {
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return op
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}
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func asUnion(t Type) *Union {
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op, _ := optype(t).(*Union)
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return op
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}
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func asInterface(t Type) *Interface {
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op, _ := optype(t).(*Interface)
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return op
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