cmd/compile: eliminate some lineno uses

Focused on ranges, selects and switches for this one.

While at it, simplify some vars in typecheckselect.

Updates #19683.

Change-Id: Ib6aabe0f6826cb1930483aeb4bb2de1ff8052d9e
Reviewed-on: https://go-review.googlesource.com/69690
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/range.go

@@ -52,7 +52,7 @@ func typecheckrange(n *Node) {
 	toomany = 0
 	switch t.Etype {
 	default:
-		yyerror("cannot range over %L", n.Right)
+		yyerrorl(n.Pos, "cannot range over %L", n.Right)
 		goto out
 
 	case TARRAY, TSLICE:
@@ -65,7 +65,7 @@ func typecheckrange(n *Node) {
 
 	case TCHAN:
 		if !t.ChanDir().CanRecv() {
-			yyerror("invalid operation: range %v (receive from send-only type %v)", n.Right, n.Right.Type)
+			yyerrorl(n.Pos, "invalid operation: range %v (receive from send-only type %v)", n.Right, n.Right.Type)
 			goto out
 		}
 
@@ -81,7 +81,7 @@ func typecheckrange(n *Node) {
 	}
 
 	if n.List.Len() > 2 || toomany != 0 {
-		yyerror("too many variables in range")
+		yyerrorl(n.Pos, "too many variables in range")
 	}
 
 	v1 = nil
@@ -108,7 +108,7 @@ func typecheckrange(n *Node) {
 		if v1.Name != nil && v1.Name.Defn == n {
 			v1.Type = t1
 		} else if v1.Type != nil && assignop(t1, v1.Type, &why) == 0 {
-			yyerror("cannot assign type %v to %L in range%s", t1, v1, why)
+			yyerrorl(n.Pos, "cannot assign type %v to %L in range%s", t1, v1, why)
 		}
 		checkassign(n, v1)
 	}
@@ -117,7 +117,7 @@ func typecheckrange(n *Node) {
 		if v2.Name != nil && v2.Name.Defn == n {
 			v2.Type = t2
 		} else if v2.Type != nil && assignop(t2, v2.Type, &why) == 0 {
-			yyerror("cannot assign type %v to %L in range%s", t2, v2, why)
+			yyerrorl(n.Pos, "cannot assign type %v to %L in range%s", t2, v2, why)
 		}
 		checkassign(n, v2)
 	}

src/cmd/compile/internal/gc/select.go

@@ -8,39 +8,32 @@ import "cmd/compile/internal/types"
 
 // select
 func typecheckselect(sel *Node) {
-	var ncase *Node
-	var n *Node
-
 	var def *Node
 	lno := setlineno(sel)
-	count := 0
 	typecheckslice(sel.Ninit.Slice(), Etop)
-	for _, n1 := range sel.List.Slice() {
+	for _, ncase := range sel.List.Slice() {
-		count++
-		ncase = n1
-		setlineno(ncase)
 		if ncase.Op != OXCASE {
+			setlineno(ncase)
 			Fatalf("typecheckselect %v", ncase.Op)
 		}
 
 		if ncase.List.Len() == 0 {
 			// default
 			if def != nil {
-				yyerror("multiple defaults in select (first at %v)", def.Line())
+				yyerrorl(ncase.Pos, "multiple defaults in select (first at %v)", def.Line())
 			} else {
 				def = ncase
 			}
 		} else if ncase.List.Len() > 1 {
-			yyerror("select cases cannot be lists")
+			yyerrorl(ncase.Pos, "select cases cannot be lists")
 		} else {
 			ncase.List.SetFirst(typecheck(ncase.List.First(), Etop))
-			n = ncase.List.First()
+			n := ncase.List.First()
 			ncase.Left = n
 			ncase.List.Set(nil)
-			setlineno(n)
 			switch n.Op {
 			default:
-				yyerror("select case must be receive, send or assign recv")
+				yyerrorl(n.Pos, "select case must be receive, send or assign recv")
 
 			// convert x = <-c into OSELRECV(x, <-c).
 			// remove implicit conversions; the eventual assignment
@@ -51,7 +44,7 @@ func typecheckselect(sel *Node) {
 				}
 
 				if n.Right.Op != ORECV {
-					yyerror("select assignment must have receive on right hand side")
+					yyerrorl(n.Pos, "select assignment must have receive on right hand side")
 					break
 				}
 
@@ -60,7 +53,7 @@ func typecheckselect(sel *Node) {
 				// convert x, ok = <-c into OSELRECV2(x, <-c) with ntest=ok
 			case OAS2RECV:
 				if n.Rlist.First().Op != ORECV {
-					yyerror("select assignment must have receive on right hand side")
+					yyerrorl(n.Pos, "select assignment must have receive on right hand side")
 					break
 				}
 
@@ -72,7 +65,7 @@ func typecheckselect(sel *Node) {
 
 				// convert <-c into OSELRECV(N, <-c)
 			case ORECV:
-				n = nod(OSELRECV, nil, n)
+				n = nodl(n.Pos, OSELRECV, nil, n)
 
 				n.SetTypecheck(1)
 				ncase.Left = n
@@ -85,7 +78,7 @@ func typecheckselect(sel *Node) {
 		typecheckslice(ncase.Nbody.Slice(), Etop)
 	}
 
-	sel.Xoffset = int64(count)
+	sel.Xoffset = int64(sel.List.Len())
 	lineno = lno
 }
 

src/cmd/compile/internal/gc/swt.go

@@ -393,7 +393,7 @@ func casebody(sw *Node, typeswvar *Node) {
 		case 0:
 			// default
 			if def != nil {
-				yyerror("more than one default case")
+				yyerrorl(n.Pos, "more than one default case")
 			}
 			// reuse original default case
 			n.Right = jmp
@@ -673,14 +673,13 @@ func (s *typeSwitch) walk(sw *Node) {
 		return
 	}
 	if cond.Right == nil {
-		setlineno(sw)
+		yyerrorl(sw.Pos, "type switch must have an assignment")
-		yyerror("type switch must have an assignment")
 		return
 	}
 
 	cond.Right = walkexpr(cond.Right, &sw.Ninit)
 	if !cond.Right.Type.IsInterface() {
-		yyerror("type switch must be on an interface")
+		yyerrorl(sw.Pos, "type switch must be on an interface")
 		return
 	}