go/types, types2: move xlist next to targs in Checker.arguments signature

targs and xlist belong together (xlist contains the type expressions for
each of the type arguments).

Also, in builtins.go, rename xlist to alist2 to avoid some confusion.

Preparation for adding more parameters to the Checker.arguments signature.

Change-Id: I960501cfd2b88410ec0d581a6520a4e80fcdc56a
Reviewed-on: https://go-review.googlesource.com/c/go/+/494121
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

Author: griesemer

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

@@ -133,17 +133,17 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// check general case by creating custom signature
 		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
 		sig.variadic = true
-		var xlist []*operand
+		var alist2 []*operand
 		// convert []operand to []*operand
 		for i := range alist {
-			xlist = append(xlist, &alist[i])
+			alist2 = append(alist2, &alist[i])
 		}
 		for i := len(alist); i < nargs; i++ {
 			var x operand
 			arg(&x, i)
-			xlist = append(xlist, &x)
+			alist2 = append(alist2, &x)
 		}
-		check.arguments(call, sig, nil, xlist, nil) // discard result (we know the result type)
+		check.arguments(call, sig, nil, nil, alist2) // discard result (we know the result type)
 		// ok to continue even if check.arguments reported errors
 
 		x.mode = value

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

@@ -325,7 +325,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 
 	// evaluate arguments
 	args := check.genericExprList(call.ArgList)
-	sig = check.arguments(call, sig, targs, args, xlist)
+	sig = check.arguments(call, sig, targs, xlist, args)
 
 	if wasGeneric && sig.TypeParams().Len() == 0 {
 		// update the recorded type of call.Fun to its instantiated type
@@ -419,7 +419,7 @@ func (check *Checker) genericExprList(elist []syntax.Expr) []*operand {
 }
 
 // xlist is the list of type argument expressions supplied in the source code.
-func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []Type, args []*operand, xlist []syntax.Expr) (rsig *Signature) {
+func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []Type, xlist []syntax.Expr, args []*operand) (rsig *Signature) {
 	rsig = sig
 
 	// TODO(gri) try to eliminate this extra verification loop

src/go/types/builtins.go

@@ -134,17 +134,17 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// check general case by creating custom signature
 		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
 		sig.variadic = true
-		var xlist []*operand
+		var alist2 []*operand
 		// convert []operand to []*operand
 		for i := range alist {
-			xlist = append(xlist, &alist[i])
+			alist2 = append(alist2, &alist[i])
 		}
 		for i := len(alist); i < nargs; i++ {
 			var x operand
 			arg(&x, i)
-			xlist = append(xlist, &x)
+			alist2 = append(alist2, &x)
 		}
-		check.arguments(call, sig, nil, xlist, nil) // discard result (we know the result type)
+		check.arguments(call, sig, nil, nil, alist2) // discard result (we know the result type)
 		// ok to continue even if check.arguments reported errors
 
 		x.mode = value

src/go/types/call.go

@@ -330,7 +330,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 
 	// evaluate arguments
 	args := check.genericExprList(call.Args)
-	sig = check.arguments(call, sig, targs, args, xlist)
+	sig = check.arguments(call, sig, targs, xlist, args)
 
 	if wasGeneric && sig.TypeParams().Len() == 0 {
 		// Update the recorded type of call.Fun to its instantiated type.
@@ -424,7 +424,7 @@ func (check *Checker) genericExprList(elist []ast.Expr) []*operand {
 }
 
 // xlist is the list of type argument expressions supplied in the source code.
-func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type, args []*operand, xlist []ast.Expr) (rsig *Signature) {
+func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type, xlist []ast.Expr, args []*operand) (rsig *Signature) {
 	rsig = sig
 
 	// TODO(gri) try to eliminate this extra verification loop