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cmd/compile/internal/types2: remove targs from substMap

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Now that we always capture targs when constructing an instance, we no
longer need to pass them via the substMap. This simplifies the code and
resolves a TODO.

Change-Id: I592dccaeb89c7cc31ac037d919137bb762820365
Reviewed-on: https://go-review.googlesource.com/c/go/+/341859
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>
This commit is contained in:
Robert Findley 2021-08-12 15:03:45 -04:00
parent 456759b246
commit b2253c8041
2 changed files with 34 additions and 51 deletions
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2
src/cmd/compile/internal/types2/instantiate.go
View file

@ -152,7 +152,7 @@ func (check *Checker) verify(pos syntax.Pos, tparams []*TypeName, targs []Type,
// parameter tpar (after any of its type parameters have been substituted through smap).
// A suitable error is reported if the result is false.
// TODO(gri) This should be a method of interfaces or type sets.
func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap *substMap) bool {
func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap substMap) bool {
iface := tpar.iface()
if iface.Empty() {
return true // no type bound

83
src/cmd/compile/internal/types2/subst.go
View file

@ -9,38 +9,27 @@ package types2
import (
"bytes"
"cmd/compile/internal/syntax"
"fmt"
)
type substMap struct {
// The targs field is currently needed for *Named type substitution.
// TODO(gri) rewrite that code, get rid of this field, and make this
// struct just the map (proj)
targs []Type
proj map[*TypeParam]Type
}
type substMap map[*TypeParam]Type
// makeSubstMap creates a new substitution map mapping tpars[i] to targs[i].
// If targs[i] is nil, tpars[i] is not substituted.
func makeSubstMap(tpars []*TypeName, targs []Type) *substMap {
func makeSubstMap(tpars []*TypeName, targs []Type) substMap {
assert(len(tpars) == len(targs))
proj := make(map[*TypeParam]Type, len(tpars))
proj := make(substMap, len(tpars))
for i, tpar := range tpars {
proj[tpar.typ.(*TypeParam)] = targs[i]
}
return &substMap{targs, proj}
return proj
}
func (m *substMap) String() string {
return fmt.Sprintf("%s", m.proj)
func (m substMap) empty() bool {
return len(m) == 0
}
func (m *substMap) empty() bool {
return len(m.proj) == 0
}
func (m *substMap) lookup(tpar *TypeParam) Type {
if t := m.proj[tpar]; t != nil {
func (m substMap) lookup(tpar *TypeParam) Type {
if t := m[tpar]; t != nil {
return t
}
return tpar
@ -53,7 +42,7 @@ func (m *substMap) lookup(tpar *TypeParam) Type {
// from the incoming type.
//
// If the given typMap is nil and check is non-nil, check.typMap is used.
func (check *Checker) subst(pos syntax.Pos, typ Type, smap *substMap, typMap map[string]*Named) Type {
func (check *Checker) subst(pos syntax.Pos, typ Type, smap substMap, typMap map[string]*Named) Type {
if smap.empty() {
return typ
}
@ -91,7 +80,7 @@ func (check *Checker) subst(pos syntax.Pos, typ Type, smap *substMap, typMap map
type subster struct {
pos syntax.Pos
smap *substMap
smap substMap
check *Checker // nil if called via Instantiate
typMap map[string]*Named
}
@ -199,40 +188,34 @@ func (subst *subster) typ(typ Type) Type {
return t // type is not parameterized
}
var new_targs []Type
var newTArgs []Type
assert(len(t.targs) == t.TParams().Len())
if len(t.targs) > 0 {
// already instantiated
dump(">>> %s already instantiated", t)
assert(len(t.targs) == t.TParams().Len())
// For each (existing) type argument targ, determine if it needs
// to be substituted; i.e., if it is or contains a type parameter
// that has a type argument for it.
for i, targ := range t.targs {
dump(">>> %d targ = %s", i, targ)
new_targ := subst.typ(targ)
if new_targ != targ {
dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
if new_targs == nil {
new_targs = make([]Type, t.TParams().Len())
copy(new_targs, t.targs)
}
new_targs[i] = new_targ
// already instantiated
dump(">>> %s already instantiated", t)
// For each (existing) type argument targ, determine if it needs
// to be substituted; i.e., if it is or contains a type parameter
// that has a type argument for it.
for i, targ := range t.targs {
dump(">>> %d targ = %s", i, targ)
new_targ := subst.typ(targ)
if new_targ != targ {
dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
if newTArgs == nil {
newTArgs = make([]Type, t.TParams().Len())
copy(newTArgs, t.targs)
}
newTArgs[i] = new_targ
}
}
if new_targs == nil {
dump(">>> nothing to substitute in %s", t)
return t // nothing to substitute
}
} else {
// not yet instantiated
dump(">>> first instantiation of %s", t)
new_targs = subst.smap.targs
if newTArgs == nil {
dump(">>> nothing to substitute in %s", t)
return t // nothing to substitute
}
// before creating a new named type, check if we have this one already
h := instantiatedHash(t, new_targs)
h := instantiatedHash(t, newTArgs)
dump(">>> new type hash: %s", h)
if named, found := subst.typMap[h]; found {
dump(">>> found %s", named)
@ -243,12 +226,12 @@ func (subst *subster) typ(typ Type) Type {
tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
t.load()
named := subst.check.newNamed(tname, t.orig, t.underlying, t.TParams(), t.methods) // method signatures are updated lazily
named.targs = new_targs
named.targs = newTArgs
subst.typMap[h] = named
t.expand(subst.typMap) // must happen after typMap update to avoid infinite recursion
// do the substitution
dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, new_targs)
dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTArgs)
named.underlying = subst.typOrNil(t.underlying)
dump(">>> underlying: %v", named.underlying)
assert(named.underlying != nil)