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[dev.typeparams] go/types: replace types2.Instantiate with Checker.Instantiate
This is a partial port of CL 333569 containing just changes to go/types. Changes to the importer wil be made in a separate CL. Change-Id: I9383e260b76402875ca6eb23c4478a6a3e8c1f0d Reviewed-on: https://go-review.googlesource.com/c/go/+/335071 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> Reviewed-by: Robert Griesemer <gri@golang.org> TryBot-Result: Go Bot <gobot@golang.org>
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@ -1833,7 +1833,9 @@ func TestInstantiate(t *testing.T) {
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}
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// instantiation should succeed (no endless recursion)
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res := Instantiate(token.NoPos, T, []Type{Typ[Int]})
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// even with a nil *Checker
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var check *Checker
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res := check.Instantiate(token.NoPos, T, []Type{Typ[Int]}, nil, false)
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// instantiated type should point to itself
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if res.Underlying().(*Pointer).Elem() != res {
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@ -60,7 +60,7 @@ func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
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}
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// instantiate function signature
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res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
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res := check.Instantiate(x.Pos(), sig, targs, poslist, true).(*Signature)
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assert(res.tparams == nil) // signature is not generic anymore
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if inferred {
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check.recordInferred(ix.Orig, targs, res)
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@ -333,7 +333,7 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
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}
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// compute result signature
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rsig = check.instantiate(call.Pos(), sig, targs, nil).(*Signature)
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rsig = check.Instantiate(call.Pos(), sig, targs, nil, true).(*Signature)
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assert(rsig.tparams == nil) // signature is not generic anymore
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check.recordInferred(call, targs, rsig)
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@ -16,6 +16,7 @@ type instance struct {
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base *Named // parameterized type to be instantiated
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targs []Type // type arguments
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poslist []token.Pos // position of each targ; for error reporting only
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verify bool // if set, constraint satisfaction is verified
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value Type // base[targs...] after instantiation or Typ[Invalid]; nil if not yet set
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}
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@ -25,7 +26,7 @@ type instance struct {
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func (t *instance) expand() Type {
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v := t.value
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if v == nil {
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v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist)
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v = t.check.Instantiate(t.pos, t.base, t.targs, t.poslist, t.verify)
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if v == nil {
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v = Typ[Invalid]
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}
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@ -9,71 +9,19 @@ import (
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"go/token"
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)
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// Instantiate instantiates the type typ with the given type arguments.
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// typ must be a *Named or a *Signature type, it must be generic, and
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// its number of type parameters must match the number of provided type
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// arguments. The result is a new, instantiated (not generic) type of
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// the same kind (either a *Named or a *Signature). The type arguments
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// are not checked against the constraints of the type parameters.
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// Any methods attached to a *Named are simply copied; they are not
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// instantiated.
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func Instantiate(pos token.Pos, typ Type, targs []Type) (res Type) {
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// TODO(gri) This code is basically identical to the prolog
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// in Checker.instantiate. Factor.
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var tparams []*TypeName
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switch t := typ.(type) {
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case *Named:
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tparams = t.TParams()
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case *Signature:
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tparams = t.tparams
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defer func() {
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// If we had an unexpected failure somewhere don't panic below when
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// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
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// is returned.
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if _, ok := res.(*Signature); !ok {
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return
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}
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// If the signature doesn't use its type parameters, subst
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// will not make a copy. In that case, make a copy now (so
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// we can set tparams to nil w/o causing side-effects).
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if t == res {
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copy := *t
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res = ©
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}
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// After instantiating a generic signature, it is not generic
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// anymore; we need to set tparams to nil.
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res.(*Signature).tparams = nil
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}()
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default:
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panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
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}
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// the number of supplied types must match the number of type parameters
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if len(targs) != len(tparams) {
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panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
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}
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if len(tparams) == 0 {
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return typ // nothing to do (minor optimization)
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}
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smap := makeSubstMap(tparams, targs)
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return (*Checker)(nil).subst(pos, typ, smap)
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}
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// InstantiateLazy is like Instantiate, but avoids actually
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// instantiating the type until needed.
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func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type) (res Type) {
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func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, verify bool) (res Type) {
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base := asNamed(typ)
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if base == nil {
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panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
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}
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return &instance{
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check: check,
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pos: pos,
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base: base,
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targs: targs,
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check: check,
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pos: pos,
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base: base,
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targs: targs,
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verify: verify,
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}
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}
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@ -32,7 +32,7 @@ func TestSizeof(t *testing.T) {
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{Chan{}, 12, 24},
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{Named{}, 84, 160},
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{TypeParam{}, 28, 48},
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{instance{}, 44, 88},
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{instance{}, 48, 96},
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{top{}, 0, 0},
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// Objects
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@ -56,8 +56,24 @@ func (m *substMap) lookup(tpar *TypeParam) Type {
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return tpar
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}
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func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist []token.Pos) (res Type) {
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if trace {
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// Instantiate instantiates the type typ with the given type arguments
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// targs. To check type constraint satisfaction, verify must be set.
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// pos and posList correspond to the instantiation and type argument
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// positions respectively; posList may be nil or shorter than the number
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// of type arguments provided.
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// typ must be a *Named or a *Signature type, and its number of type
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// parameters must match the number of provided type arguments.
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// The receiver (check) may be nil if and only if verify is not set.
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// The result is a new, instantiated (not generic) type of the same kind
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// (either a *Named or a *Signature).
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// Any methods attached to a *Named are simply copied; they are not
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// instantiated.
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func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList []token.Pos, verify bool) (res Type) {
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if verify && check == nil {
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panic("cannot have nil receiver if verify is set")
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}
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if check != nil && trace {
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check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
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check.indent++
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defer func() {
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@ -73,7 +89,7 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
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}()
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}
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assert(len(poslist) <= len(targs))
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assert(len(posList) <= len(targs))
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// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
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var tparams []*TypeName
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@ -100,17 +116,19 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
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// anymore; we need to set tparams to nil.
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res.(*Signature).tparams = nil
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}()
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default:
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check.dump("%v: cannot instantiate %v", pos, typ)
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unreachable() // only defined types and (defined) functions can be generic
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// only types and functions can be generic
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panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
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}
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// the number of supplied types must match the number of type parameters
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if len(targs) != len(tparams) {
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// TODO(gri) provide better error message
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check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", len(targs), len(tparams))
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return Typ[Invalid]
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if check != nil {
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check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", len(targs), len(tparams))
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return Typ[Invalid]
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}
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panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
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}
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if len(tparams) == 0 {
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@ -120,16 +138,18 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
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smap := makeSubstMap(tparams, targs)
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// check bounds
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for i, tname := range tparams {
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// best position for error reporting
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pos := pos
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if i < len(poslist) {
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pos = poslist[i]
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}
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if verify {
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for i, tname := range tparams {
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// best position for error reporting
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pos := pos
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if i < len(posList) {
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pos = posList[i]
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}
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// stop checking bounds after the first failure
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if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
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break
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// stop checking bounds after the first failure
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if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
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break
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}
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}
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}
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@ -413,12 +413,14 @@ func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) Typ
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// create a new type instance rather than instantiate the type
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// TODO(gri) should do argument number check here rather than
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// when instantiating the type?
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// TODO(gri) use InstantiateLazy here (cleanup)
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typ := new(instance)
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def.setUnderlying(typ)
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typ.check = check
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typ.pos = ix.X.Pos()
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typ.base = base
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typ.verify = true
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// evaluate arguments (always)
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typ.targs = check.typeList(ix.Indices)
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