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[dev.typeparams] cmd/compile/internal/types2: trigger verification while resolving instance

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This is a straight port of CL 335978 with minor adjustements to
white space and an error message.

Change-Id: Icfcb562f75802a119ce5d02427bffecf7e279b2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/338097
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-07-28 13:50:09 -07:00
parent ff0c0dbca6
commit c079b6baaa
3 changed files with 37 additions and 28 deletions
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2
src/cmd/compile/internal/types2/instance.go
View File

@ -26,7 +26,7 @@ func (n *Named) expand() {
// tparams. This is done implicitly by the call to n.TParams, but making it
// explicit is harmless: load is idempotent.
n.load()
inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams(), n.targs, n.instance.posList, n.instance.verify)
inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams(), n.targs, n.instance.posList)
n.underlying = inst
n.fromRHS = inst
n.instance = nil

59
src/cmd/compile/internal/types2/instantiate.go
View File

@ -54,10 +54,15 @@ func (check *Checker) Instantiate(pos syntax.Pos, typ Type, targs []Type, posLis
// only types and functions can be generic
panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
}
return check.instantiate(pos, typ, tparams, targs, posList, verify)
inst := check.instantiate(pos, typ, tparams, targs, posList)
if verify && len(tparams) == len(targs) {
check.verify(pos, tparams, targs, posList)
}
return inst
}
func (check *Checker) instantiate(pos syntax.Pos, typ Type, tparams []*TypeName, targs []Type, posList []syntax.Pos, verify bool) (res Type) {
func (check *Checker) instantiate(pos syntax.Pos, typ Type, tparams []*TypeName, targs []Type, posList []syntax.Pos) (res Type) {
// the number of supplied types must match the number of type parameters
if len(targs) != len(tparams) {
// TODO(gri) provide better error message
@ -67,9 +72,6 @@ func (check *Checker) instantiate(pos syntax.Pos, typ Type, tparams []*TypeName,
}
panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
}
if verify && check == nil {
panic("cannot have nil receiver if verify is set")
}
if check != nil && check.conf.Trace {
check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
@ -93,24 +95,7 @@ func (check *Checker) instantiate(pos syntax.Pos, typ Type, tparams []*TypeName,
return typ // nothing to do (minor optimization)
}
smap := makeSubstMap(tparams, targs)
// check bounds
if verify {
for i, tname := range tparams {
// best position for error reporting
pos := pos
if i < len(posList) {
pos = posList[i]
}
// stop checking bounds after the first failure
if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
break
}
}
}
return check.subst(pos, typ, smap)
return check.subst(pos, typ, makeSubstMap(tparams, targs))
}
// InstantiateLazy is like Instantiate, but avoids actually
@ -120,10 +105,16 @@ func (check *Checker) InstantiateLazy(pos syntax.Pos, typ Type, targs []Type, po
// Don't use asNamed here: we don't want to expand the base during lazy
// instantiation.
base := typ.(*Named)
if base == nil {
panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
}
if verify && len(base.tparams) == len(targs) {
check.later(func() {
check.verify(pos, base.tparams, targs, posList)
})
}
h := instantiatedHash(base, targs)
if check != nil {
// typ may already have been instantiated with identical type arguments. In
@ -148,6 +139,26 @@ func (check *Checker) InstantiateLazy(pos syntax.Pos, typ Type, targs []Type, po
return named
}
func (check *Checker) verify(pos syntax.Pos, tparams []*TypeName, targs []Type, posList []syntax.Pos) {
if check == nil {
panic("cannot have nil Checker if verifying constraints")
}
smap := makeSubstMap(tparams, targs)
for i, tname := range tparams {
// best position for error reporting
pos := pos
if i < len(posList) {
pos = posList[i]
}
// stop checking bounds after the first failure
if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
break
}
}
}
// satisfies reports whether the type argument targ satisfies the constraint of type parameter
// parameter tpar (after any of its type parameters have been substituted through smap).
// A suitable error is reported if the result is false.

4
src/cmd/compile/internal/types2/testdata/check/issues.go2 vendored
View File

@ -74,10 +74,8 @@ func (u T2[U]) Add1() U {
return u.s + 1
}
// TODO(rfindley): we should probably report an error here as well, not
// just when the type is first instantiated.
func NewT2[U any]() T2[U /* ERROR U has no constraints */ ] {
return T2[U]{}
return T2[U /* ERROR U has no constraints */ ]{}
}
func _() {