cmd/compile/internal/types2: remove concept of finals

This is a 1:1 port of the respective change in go/types
in https://golang.org/cl/299590.

Change-Id: I65ad723f2e21e3d95fc0b94665e0121e31871a48
Reviewed-on: https://go-review.googlesource.com/c/go/+/300250
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/compile/internal/types2/check.go

@@ -107,7 +107,6 @@ type Checker struct {
 	methods  map[*TypeName][]*Func    // maps package scope type names to associated non-blank (non-interface) methods
 	untyped  map[syntax.Expr]exprInfo // map of expressions without final type
 	delayed  []func()                 // stack of delayed action segments; segments are processed in FIFO order
-	finals   []func()                 // list of final actions; processed at the end of type-checking the current set of files
 	objPath  []Object                 // path of object dependencies during type inference (for cycle reporting)
 
 	// context within which the current object is type-checked
@@ -147,14 +146,6 @@ func (check *Checker) later(f func()) {
 	check.delayed = append(check.delayed, f)
 }
 
-// atEnd adds f to the list of actions processed at the end
-// of type-checking, before initialization order computation.
-// Actions added by atEnd are processed after any actions
-// added by later.
-func (check *Checker) atEnd(f func()) {
-	check.finals = append(check.finals, f)
-}
-
 // push pushes obj onto the object path and returns its index in the path.
 func (check *Checker) push(obj Object) int {
 	check.objPath = append(check.objPath, obj)
@@ -214,7 +205,6 @@ func (check *Checker) initFiles(files []*syntax.File) {
 	check.methods = nil
 	check.untyped = nil
 	check.delayed = nil
-	check.finals = nil
 
 	// determine package name and collect valid files
 	pkg := check.pkg
@@ -281,7 +271,6 @@ func (check *Checker) checkFiles(files []*syntax.File) (err error) {
 
 	print("== processDelayed ==")
 	check.processDelayed(0) // incl. all functions
-	check.processFinals()
 
 	print("== initOrder ==")
 	check.initOrder()
@@ -324,16 +313,6 @@ func (check *Checker) processDelayed(top int) {
 	check.delayed = check.delayed[:top]
 }
 
-func (check *Checker) processFinals() {
-	n := len(check.finals)
-	for _, f := range check.finals {
-		f() // must not append to check.finals
-	}
-	if len(check.finals) != n {
-		panic("internal error: final action list grew")
-	}
-}
-
 func (check *Checker) recordUntyped() {
 	if !debug && check.Types == nil {
 		return // nothing to do

src/cmd/compile/internal/types2/typexpr.go

@@ -141,7 +141,7 @@ func (check *Checker) ordinaryType(pos syntax.Pos, typ Type) {
 	// We don't want to call under() (via Interface) or complete interfaces while we
 	// are in the middle of type-checking parameter declarations that might belong to
 	// interface methods. Delay this check to the end of type-checking.
-	check.atEnd(func() {
+	check.later(func() {
 		if t := asInterface(typ); t != nil {
 			check.completeInterface(pos, t) // TODO(gri) is this the correct position?
 			if t.allTypes != nil {
@@ -574,7 +574,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *Named) (T Type) {
 		//
 		// Delay this check because it requires fully setup types;
 		// it is safe to continue in any case (was issue 6667).
-		check.atEnd(func() {
+		check.later(func() {
 			if !Comparable(typ.key) {
 				var why string
 				if asTypeParam(typ.key) != nil {
@@ -676,7 +676,7 @@ func (check *Checker) instantiatedType(x syntax.Expr, targs []syntax.Expr, def *
 
 	// make sure we check instantiation works at least once
 	// and that the resulting type is valid
-	check.atEnd(func() {
+	check.later(func() {
 		t := typ.expand()
 		check.validType(t, nil)
 	})
@@ -954,7 +954,7 @@ func (check *Checker) completeInterface(pos syntax.Pos, ityp *Interface) {
 			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
 			// error here as well (even though we could do it eagerly) because it's the same
 			// error message.
-			check.atEnd(func() {
+			check.later(func() {
 				if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
 					var err error_
 					err.errorf(pos, "duplicate method %s", m.name)
@@ -1170,7 +1170,7 @@ func (check *Checker) structType(styp *Struct, e *syntax.StructType) {
 			// (via under(t)) a possibly incomplete type.
 			embeddedTyp := typ // for closure below
 			embeddedPos := pos
-			check.atEnd(func() {
+			check.later(func() {
 				t, isPtr := deref(embeddedTyp)
 				switch t := optype(t).(type) {
 				case *Basic:
@@ -1230,7 +1230,7 @@ func (check *Checker) collectTypeConstraints(pos syntax.Pos, types []syntax.Expr
 	// interfaces, which may not be complete yet. It's ok to do this check at the
 	// end because it's not a requirement for correctness of the code.
 	// Note: This is a quadratic algorithm, but type lists tend to be short.
-	check.atEnd(func() {
+	check.later(func() {
 		for i, t := range list {
 			if t := asInterface(t); t != nil {
 				check.completeInterface(types[i].Pos(), t)