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[dev.typeparams] cmd/compile/internal/types: review of infer.go

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The changes between (equivalent, and reviewed) go/types/infer.go
and infer.go can be seen by comparing patchset 1 and 2. The actual
change is just removing the "// UNREVIEWED" marker and fixing a
few comments.

Change-Id: Ieb0c07c325a2e446550f85b159f99d4dfe5f1d5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/291171
Reviewed-by: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
This commit is contained in:
Robert Griesemer 2021-02-10 17:21:23 -08:00
parent 9168590977
commit bab3461123
1 changed files with 6 additions and 10 deletions
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16
src/cmd/compile/internal/types2/infer.go
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@ -1,4 +1,3 @@
// UNREVIEWED
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
@ -15,7 +14,7 @@ import "bytes"
// is impossible because unification fails, an error is reported and the resulting types list is
// nil, and index is 0. Otherwise, types is the list of inferred type arguments, and index is
// the index of the first type argument in that list that couldn't be inferred (and thus is nil).
// If all type arguments where inferred successfully, index is < 0.
// If all type arguments were inferred successfully, index is < 0.
func (check *Checker) infer(tparams []*TypeName, params *Tuple, args []*operand) (types []Type, index int) {
assert(params.Len() == len(args))
@ -70,7 +69,7 @@ func (check *Checker) infer(tparams []*TypeName, params *Tuple, args []*operand)
if targ := arg.typ; isTyped(targ) {
// If we permit bidirectional unification, and targ is
// a generic function, we need to initialize u.y with
// the respectice type parameters of targ.
// the respective type parameters of targ.
if !u.unify(par.typ, targ) {
errorf("type", par.typ, targ, arg)
return nil, 0
@ -292,19 +291,17 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type) (types []Type, i
typ := tpar.typ.(*TypeParam)
sbound := check.structuralType(typ.bound.Under())
if sbound != nil {
//check.dump(">>> unify(%s, %s)", tpar, sbound)
if !u.unify(typ, sbound) {
check.errorf(tpar.pos, "%s does not match %s", tpar, sbound)
return nil, 0
}
//check.dump(">>> => indices = %v, types = %s", u.x.indices, u.types)
}
}
// u.x.types() now contains the incoming type arguments plus any additional type
// arguments for which there were structural constraints. The newly inferred non-
// nil entries may still contain references to other type parameters. For instance,
// for [type A interface{}, B interface{type []C}, C interface{type *A}], if A == int
// for [A any, B interface{type []C}, C interface{type *A}], if A == int
// was given, unification produced the type list [int, []C, *A]. We eliminate the
// remaining type parameters by substituting the type parameters in this type list
// until nothing changes anymore.
@ -316,7 +313,7 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type) (types []Type, i
}
// dirty tracks the indices of all types that may still contain type parameters.
// We know that nil types entries and entries corresponding to provided (non-nil)
// We know that nil type entries and entries corresponding to provided (non-nil)
// type arguments are clean, so exclude them from the start.
var dirty []int
for i, typ := range types {
@ -326,8 +323,8 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type) (types []Type, i
}
for len(dirty) > 0 {
// TODO(gri) Instead of creating a new smap for each iteration,
// provide an update operation for smaps and only change when
// TODO(gri) Instead of creating a new substMap for each iteration,
// provide an update operation for substMaps and only change when
// needed. Optimization.
smap := makeSubstMap(tparams, types)
n := 0
@ -341,7 +338,6 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type) (types []Type, i
}
dirty = dirty[:n]
}
//check.dump(">>> inferred types = %s", types)
return
}