diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/unify.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/unify.go | 81 |
1 files changed, 38 insertions, 43 deletions
diff --git a/src/cmd/compile/internal/types2/unify.go b/src/cmd/compile/internal/types2/unify.go index e1832bbb2a..d4fbebc11b 100644 --- a/src/cmd/compile/internal/types2/unify.go +++ b/src/cmd/compile/internal/types2/unify.go @@ -6,7 +6,10 @@ package types2 -import "bytes" +import ( + "bytes" + "fmt" +) // The unifier maintains two separate sets of type parameters x and y // which are used to resolve type parameters in the x and y arguments @@ -34,7 +37,6 @@ import "bytes" // and the respective types inferred for each type parameter. // A unifier is created by calling newUnifier. type unifier struct { - check *Checker exact bool x, y tparamsList // x and y must initialized via tparamsList.init types []Type // inferred types, shared by x and y @@ -45,8 +47,8 @@ type unifier struct { // exactly. If exact is not set, a named type's underlying type // is considered if unification would fail otherwise, and the // direction of channels is ignored. -func newUnifier(check *Checker, exact bool) *unifier { - u := &unifier{check: check, exact: exact} +func newUnifier(exact bool) *unifier { + u := &unifier{exact: exact} u.x.unifier = u u.y.unifier = u return u @@ -60,7 +62,7 @@ func (u *unifier) unify(x, y Type) bool { // A tparamsList describes a list of type parameters and the types inferred for them. type tparamsList struct { unifier *unifier - tparams []*TypeName + tparams []*TypeParam // For each tparams element, there is a corresponding type slot index in indices. // index < 0: unifier.types[-index-1] == nil // index == 0: no type slot allocated yet @@ -75,11 +77,11 @@ type tparamsList struct { func (d *tparamsList) String() string { var buf bytes.Buffer buf.WriteByte('[') - for i, tname := range d.tparams { + for i, tpar := range d.tparams { if i > 0 { buf.WriteString(", ") } - writeType(&buf, tname.typ, nil, nil) + writeType(&buf, tpar, nil, nil) buf.WriteString(": ") writeType(&buf, d.at(i), nil, nil) } @@ -90,13 +92,13 @@ func (d *tparamsList) String() string { // init initializes d with the given type parameters. // The type parameters must be in the order in which they appear in their declaration // (this ensures that the tparams indices match the respective type parameter index). -func (d *tparamsList) init(tparams []*TypeName) { +func (d *tparamsList) init(tparams []*TypeParam) { if len(tparams) == 0 { return } if debug { for i, tpar := range tparams { - assert(i == tpar.typ.(*TypeParam).index) + assert(i == tpar.index) } } d.tparams = tparams @@ -148,10 +150,17 @@ func (u *unifier) join(i, j int) bool { // If typ is a type parameter of d, index returns the type parameter index. // Otherwise, the result is < 0. func (d *tparamsList) index(typ Type) int { - if t, ok := typ.(*TypeParam); ok { - if i := t.index; i < len(d.tparams) && d.tparams[i].typ == t { - return i - } + if tpar, ok := typ.(*TypeParam); ok { + return tparamIndex(d.tparams, tpar) + } + return -1 +} + +// If tpar is a type parameter in list, tparamIndex returns the type parameter index. +// Otherwise, the result is < 0. tpar must not be nil. +func tparamIndex(list []*TypeParam, tpar *TypeParam) int { + if i := tpar.index; i < len(list) && list[i] == tpar { + return i } return -1 } @@ -220,10 +229,6 @@ func (u *unifier) nifyEq(x, y Type, p *ifacePair) bool { // code the corresponding changes should be made here. // Must not be called directly from outside the unifier. func (u *unifier) nify(x, y Type, p *ifacePair) bool { - // types must be expanded for comparison - x = expand(x) - y = expand(y) - if !u.exact { // If exact unification is known to fail because we attempt to // match a type name against an unnamed type literal, consider @@ -352,25 +357,18 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool { u.nify(x.results, y.results, p) } - case *Sum: - // This should not happen with the current internal use of sum types. - panic("type inference across sum types not implemented") - case *Interface: // Two interface types are identical if they have the same set of methods with // the same names and identical function types. Lower-case method names from // different packages are always different. The order of the methods is irrelevant. if y, ok := y.(*Interface); ok { - // If identical0 is called (indirectly) via an external API entry point - // (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in - // that case, interfaces are expected to be complete and lazy completion - // here is not needed. - if u.check != nil { - u.check.completeInterface(nopos, x) - u.check.completeInterface(nopos, y) + xset := x.typeSet() + yset := y.typeSet() + if !xset.terms.equal(yset.terms) { + return false } - a := x.allMethods - b := y.allMethods + a := xset.methods + b := yset.methods if len(a) == len(b) { // Interface types are the only types where cycles can occur // that are not "terminated" via named types; and such cycles @@ -428,19 +426,20 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool { } case *Named: - // Two named types are identical if their type names originate - // in the same type declaration. - // if y, ok := y.(*Named); ok { - // return x.obj == y.obj - // } if y, ok := y.(*Named); ok { + x.expand(nil) + y.expand(nil) + + xargs := x.targs.list() + yargs := y.targs.list() + // TODO(gri) This is not always correct: two types may have the same names // in the same package if one of them is nested in a function. // Extremely unlikely but we need an always correct solution. if x.obj.pkg == y.obj.pkg && x.obj.name == y.obj.name { - assert(len(x.targs) == len(y.targs)) - for i, x := range x.targs { - if !u.nify(x, y.targs[i], p) { + assert(len(xargs) == len(yargs)) + for i, x := range xargs { + if !u.nify(x, yargs[i], p) { return false } } @@ -454,15 +453,11 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool { // are identical if they originate in the same declaration. return x == y - // case *instance: - // unreachable since types are expanded - case nil: // avoid a crash in case of nil type default: - u.check.dump("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams) - unreachable() + panic(fmt.Sprintf("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams)) } return false |