go/types, types2: factor out hasDots to check for ... arguments in calls (cleanup)

This further reduces the differences between go/types and types2.

Change-Id: Ie651c13dd12ecf043b8be92655d48d1ce32d4c5d
Reviewed-on: https://go-review.googlesource.com/c/go/+/562777
Reviewed-by: Robert Griesemer <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
Run-TryBot: Robert Griesemer <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: griesemer

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

@@ -22,7 +22,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 	// append is the only built-in that permits the use of ... for the last argument
 	bin := predeclaredFuncs[id]
-	if call.HasDots && id != _Append {
+	if hasDots(call) && id != _Append {
 		//check.errorf(call.Ellipsis, invalidOp + "invalid use of ... with built-in %s", bin.name)
 		check.errorf(call,
 			InvalidDotDotDot,
@@ -114,7 +114,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// spec: "As a special case, append also accepts a first argument assignable
 		// to type []byte with a second argument of string type followed by ... .
 		// This form appends the bytes of the string.
-		if nargs == 2 && call.HasDots {
+		if nargs == 2 && hasDots(call) {
 			if ok, _ := x.assignableTo(check, NewSlice(universeByte), nil); ok {
 				y := args[1]
 				if t := coreString(y.typ); t != nil && isString(t) {

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

@@ -209,7 +209,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 						break
 					}
 				}
-				if call.HasDots {
+				if hasDots(call) {
 					check.errorf(call.ArgList[0], BadDotDotDotSyntax, "invalid use of ... in conversion to %s", T)
 					break
 				}
@@ -468,7 +468,7 @@ func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []T
 
 	nargs := len(args)
 	npars := sig.params.Len()
-	ddd := call.HasDots
+	ddd := hasDots(call)
 
 	// set up parameters
 	sigParams := sig.params // adjusted for variadic functions (may be nil for empty parameter lists!)

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

@@ -20,3 +20,6 @@ import "cmd/compile/internal/syntax"
 // If p and q are in different files, p is before q if the filename
 // of p sorts lexicographically before the filename of q.
 func cmpPos(p, q syntax.Pos) int { return p.Cmp(q) }
+
+// hasDots reports whether the last argument in the call is followed by ...
+func hasDots(call *syntax.CallExpr) bool { return call.HasDots }

src/go/types/builtins.go

@@ -22,7 +22,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 	// append is the only built-in that permits the use of ... for the last argument
 	bin := predeclaredFuncs[id]
-	if call.Ellipsis.IsValid() && id != _Append {
+	if hasDots(call) && id != _Append {
 		check.errorf(atPos(call.Ellipsis),
 			InvalidDotDotDot,
 			invalidOp+"invalid use of ... with built-in %s", bin.name)
@@ -113,7 +113,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// spec: "As a special case, append also accepts a first argument assignable
 		// to type []byte with a second argument of string type followed by ... .
 		// This form appends the bytes of the string.
-		if nargs == 2 && call.Ellipsis.IsValid() {
+		if nargs == 2 && hasDots(call) {
 			if ok, _ := x.assignableTo(check, NewSlice(universeByte), nil); ok {
 				y := args[1]
 				if t := coreString(y.typ); t != nil && isString(t) {

src/go/types/call.go

@@ -206,7 +206,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 		case 1:
 			check.expr(nil, x, call.Args[0])
 			if x.mode != invalid {
-				if call.Ellipsis.IsValid() {
+				if hasDots(call) {
 					check.errorf(call.Args[0], BadDotDotDotSyntax, "invalid use of ... in conversion to %s", T)
 					break
 				}
@@ -471,7 +471,7 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
 
 	nargs := len(args)
 	npars := sig.params.Len()
-	ddd := call.Ellipsis.IsValid()
+	ddd := hasDots(call)
 
 	// set up parameters
 	sigParams := sig.params // adjusted for variadic functions (may be nil for empty parameter lists!)

src/go/types/exprstring.go

@@ -105,7 +105,7 @@ func WriteExpr(buf *bytes.Buffer, x ast.Expr) {
 		WriteExpr(buf, x.Fun)
 		buf.WriteByte('(')
 		writeExprList(buf, x.Args)
-		if x.Ellipsis.IsValid() {
+		if hasDots(x) {
 			buf.WriteString("...")
 		}
 		buf.WriteByte(')')

src/go/types/util.go

@@ -9,7 +9,10 @@
 
 package types
 
-import "go/token"
+import (
+	"go/ast"
+	"go/token"
+)
 
 // cmpPos compares the positions p and q and returns a result r as follows:
 //
@@ -20,3 +23,6 @@ import "go/token"
 // If p and q are in different files, p is before q if the filename
 // of p sorts lexicographically before the filename of q.
 func cmpPos(p, q token.Pos) int { return int(p - q) }
+
+// hasDots reports whether the last argument in the call is followed by ...
+func hasDots(call *ast.CallExpr) bool { return call.Ellipsis.IsValid() }