cmd/compile: more nodeSeq conversions

Found by temporarily flipping fields from *NodeList to Nodes and fixing
all the compilation errors.  This CL does not actually change any
fields.

Passes toolstash -cmp.

Update #14473.

Change-Id: Ib98fa37e8752f96358224c973a743618a6a0e736
Reviewed-on: https://go-review.googlesource.com/20320
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

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

@@ -187,13 +187,13 @@ func genhash(sym *Sym, t *Type) {
 	fn.Func.Nname.Name.Param.Ntype = tfn
 
 	n := Nod(ODCLFIELD, newname(Lookup("p")), typenod(Ptrto(t)))
-	tfn.List = list(tfn.List, n)
+	appendNodeSeqNode(&tfn.List, n)
 	np := n.Left
 	n = Nod(ODCLFIELD, newname(Lookup("h")), typenod(Types[TUINTPTR]))
-	tfn.List = list(tfn.List, n)
+	appendNodeSeqNode(&tfn.List, n)
 	nh := n.Left
 	n = Nod(ODCLFIELD, nil, typenod(Types[TUINTPTR])) // return value
-	tfn.Rlist = list(tfn.Rlist, n)
+	appendNodeSeqNode(&tfn.Rlist, n)
 
 	funchdr(fn)
 	typecheck(&fn.Func.Nname.Name.Param.Ntype, Etype)
@@ -218,10 +218,10 @@ func genhash(sym *Sym, t *Type) {
 		n := Nod(ORANGE, nil, Nod(OIND, np, nil))
 		ni := newname(Lookup("i"))
 		ni.Type = Types[TINT]
-		n.List = list1(ni)
+		setNodeSeq(&n.List, []*Node{ni})
 		n.Colas = true
 		colasdefn(n.List, n)
-		ni = n.List.N
+		ni = nodeSeqFirst(n.List)
 
 		// h = hashel(&p[i], h)
 		call := Nod(OCALL, hashel, nil)
@@ -230,8 +230,8 @@ func genhash(sym *Sym, t *Type) {
 		nx.Bounded = true
 		na := Nod(OADDR, nx, nil)
 		na.Etype = 1 // no escape to heap
-		call.List = list(call.List, na)
-		call.List = list(call.List, nh)
+		appendNodeSeqNode(&call.List, na)
+		appendNodeSeqNode(&call.List, nh)
 		n.Nbody.Append(Nod(OAS, nh, call))
 
 		fn.Nbody.Append(n)
@@ -259,9 +259,9 @@ func genhash(sym *Sym, t *Type) {
 				nx = Nod(OXDOT, np, newname(first.Sym)) // TODO: fields from other packages?
 				na = Nod(OADDR, nx, nil)
 				na.Etype = 1 // no escape to heap
-				call.List = list(call.List, na)
-				call.List = list(call.List, nh)
-				call.List = list(call.List, Nodintconst(size))
+				appendNodeSeqNode(&call.List, na)
+				appendNodeSeqNode(&call.List, nh)
+				appendNodeSeqNode(&call.List, Nodintconst(size))
 				fn.Nbody.Append(Nod(OAS, nh, call))
 			}
 
@@ -283,8 +283,8 @@ func genhash(sym *Sym, t *Type) {
 			nx = Nod(OXDOT, np, newname(t1.Sym)) // TODO: fields from other packages?
 			na = Nod(OADDR, nx, nil)
 			na.Etype = 1 // no escape to heap
-			call.List = list(call.List, na)
-			call.List = list(call.List, nh)
+			appendNodeSeqNode(&call.List, na)
+			appendNodeSeqNode(&call.List, nh)
 			fn.Nbody.Append(Nod(OAS, nh, call))
 
 			t1 = t1.Down
@@ -292,7 +292,7 @@ func genhash(sym *Sym, t *Type) {
 	}
 
 	r := Nod(ORETURN, nil, nil)
-	r.List = list(r.List, nh)
+	appendNodeSeqNode(&r.List, nh)
 	fn.Nbody.Append(r)
 
 	if Debug['r'] != 0 {
@@ -354,9 +354,9 @@ func hashfor(t *Type) *Node {
 	n := newname(sym)
 	n.Class = PFUNC
 	tfn := Nod(OTFUNC, nil, nil)
-	tfn.List = list(tfn.List, Nod(ODCLFIELD, nil, typenod(Ptrto(t))))
-	tfn.List = list(tfn.List, Nod(ODCLFIELD, nil, typenod(Types[TUINTPTR])))
-	tfn.Rlist = list(tfn.Rlist, Nod(ODCLFIELD, nil, typenod(Types[TUINTPTR])))
+	appendNodeSeqNode(&tfn.List, Nod(ODCLFIELD, nil, typenod(Ptrto(t))))
+	appendNodeSeqNode(&tfn.List, Nod(ODCLFIELD, nil, typenod(Types[TUINTPTR])))
+	appendNodeSeqNode(&tfn.Rlist, Nod(ODCLFIELD, nil, typenod(Types[TUINTPTR])))
 	typecheck(&tfn, Etype)
 	n.Type = tfn.Type
 	return n
@@ -382,13 +382,13 @@ func geneq(sym *Sym, t *Type) {
 	fn.Func.Nname.Name.Param.Ntype = tfn
 
 	n := Nod(ODCLFIELD, newname(Lookup("p")), typenod(Ptrto(t)))
-	tfn.List = list(tfn.List, n)
+	appendNodeSeqNode(&tfn.List, n)
 	np := n.Left
 	n = Nod(ODCLFIELD, newname(Lookup("q")), typenod(Ptrto(t)))
-	tfn.List = list(tfn.List, n)
+	appendNodeSeqNode(&tfn.List, n)
 	nq := n.Left
 	n = Nod(ODCLFIELD, nil, typenod(Types[TBOOL]))
-	tfn.Rlist = list(tfn.Rlist, n)
+	appendNodeSeqNode(&tfn.Rlist, n)
 
 	funchdr(fn)
 
@@ -413,10 +413,10 @@ func geneq(sym *Sym, t *Type) {
 
 		ni := newname(Lookup("i"))
 		ni.Type = Types[TINT]
-		nrange.List = list1(ni)
+		setNodeSeq(&nrange.List, []*Node{ni})
 		nrange.Colas = true
 		colasdefn(nrange.List, nrange)
-		ni = nrange.List.N
+		ni = nodeSeqFirst(nrange.List)
 
 		// if p[i] != q[i] { return false }
 		nx := Nod(OINDEX, np, ni)
@@ -428,14 +428,14 @@ func geneq(sym *Sym, t *Type) {
 		nif := Nod(OIF, nil, nil)
 		nif.Left = Nod(ONE, nx, ny)
 		r := Nod(ORETURN, nil, nil)
-		r.List = list(r.List, Nodbool(false))
+		appendNodeSeqNode(&r.List, Nodbool(false))
 		nif.Nbody.Append(r)
 		nrange.Nbody.Append(nif)
 		fn.Nbody.Append(nrange)
 
 		// return true
 		ret := Nod(ORETURN, nil, nil)
-		ret.List = list(ret.List, Nodbool(true))
+		appendNodeSeqNode(&ret.List, Nodbool(true))
 		fn.Nbody.Append(ret)
 
 	// Walk the struct using memequal for runs of AMEM
@@ -499,7 +499,7 @@ func geneq(sym *Sym, t *Type) {
 		}
 
 		ret := Nod(ORETURN, nil, nil)
-		ret.List = list(ret.List, and)
+		appendNodeSeqNode(&ret.List, and)
 		fn.Nbody.Append(ret)
 	}
 
@@ -556,10 +556,10 @@ func eqmem(p *Node, q *Node, field *Node, size int64) *Node {
 	typecheck(&ny, Erv)
 
 	call := Nod(OCALL, eqmemfunc(size, nx.Type.Type, &needsize), nil)
-	call.List = list(call.List, nx)
-	call.List = list(call.List, ny)
+	appendNodeSeqNode(&call.List, nx)
+	appendNodeSeqNode(&call.List, ny)
 	if needsize != 0 {
-		call.List = list(call.List, Nodintconst(size))
+		appendNodeSeqNode(&call.List, Nodintconst(size))
 	}
 
 	return call

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

@@ -849,7 +849,7 @@ func (p *exporter) node(n *Node) {
 
 	// expressions
 	case OMAKEMAP, OMAKECHAN, OMAKESLICE:
-		if p.bool(n.List != nil) {
+		if p.bool(nodeSeqLen(n.List) != 0) {
 			p.nodeList(n.List) // TODO(gri) do we still need to export this?
 		}
 		p.nodesOrNil(n.Left, n.Right)
@@ -971,7 +971,7 @@ func (p *exporter) node(n *Node) {
 		p.nodeList(n.Nbody)
 
 	case ORANGE:
-		if p.bool(n.List != nil) {
+		if p.bool(nodeSeqLen(n.List) != 0) {
 			p.nodeList(n.List)
 		}
 		p.node(n.Right)
@@ -983,7 +983,7 @@ func (p *exporter) node(n *Node) {
 		p.nodeList(n.List)
 
 	case OCASE, OXCASE:
-		if p.bool(n.List != nil) {
+		if p.bool(nodeSeqLen(n.List) != 0) {
 			p.nodeList(n.List)
 		}
 		p.nodeList(n.Nbody)

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

@@ -636,7 +636,7 @@ func (p *importer) node() *Node {
 		// }
 		x := Nod(OCALL, p.typ().Nod, nil)
 		if p.bool() {
-			x.List = list1(p.node())
+			setNodeSeq(&x.List, []*Node{p.node()})
 		} else {
 			setNodeSeq(&x.List, p.nodeList())
 		}

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

@@ -26,30 +26,30 @@ func closurehdr(ntype *Node) {
 	// references to these variables need to
 	// refer to the variables in the external
 	// function declared below; see walkclosure.
-	n.List = ntype.List
+	setNodeSeq(&n.List, ntype.List)
 
-	n.Rlist = ntype.Rlist
-	ntype.List = nil
-	ntype.Rlist = nil
-	for l := n.List; l != nil; l = l.Next {
-		name = l.N.Left
+	setNodeSeq(&n.Rlist, ntype.Rlist)
+	setNodeSeq(&ntype.List, nil)
+	setNodeSeq(&ntype.Rlist, nil)
+	for it := nodeSeqIterate(n.List); !it.Done(); it.Next() {
+		name = it.N().Left
 		if name != nil {
 			name = newname(name.Sym)
 		}
-		a = Nod(ODCLFIELD, name, l.N.Right)
-		a.Isddd = l.N.Isddd
+		a = Nod(ODCLFIELD, name, it.N().Right)
+		a.Isddd = it.N().Isddd
 		if name != nil {
 			name.Isddd = a.Isddd
 		}
-		ntype.List = list(ntype.List, a)
+		appendNodeSeqNode(&ntype.List, a)
 	}
 
-	for l := n.Rlist; l != nil; l = l.Next {
-		name = l.N.Left
+	for it := nodeSeqIterate(n.Rlist); !it.Done(); it.Next() {
+		name = it.N().Left
 		if name != nil {
 			name = newname(name.Sym)
 		}
-		ntype.Rlist = list(ntype.Rlist, Nod(ODCLFIELD, name, l.N.Right))
+		appendNodeSeqNode(&ntype.Rlist, Nod(ODCLFIELD, name, it.N().Right))
 	}
 }
 
@@ -177,8 +177,8 @@ func makeclosure(func_ *Node) *Node {
 	// that begins by reading closure parameters.
 	xtype := Nod(OTFUNC, nil, nil)
 
-	xtype.List = func_.List
-	xtype.Rlist = func_.Rlist
+	setNodeSeq(&xtype.List, func_.List)
+	setNodeSeq(&xtype.Rlist, func_.Rlist)
 
 	// create the function
 	xfunc := Nod(ODCLFUNC, nil, nil)
@@ -205,8 +205,8 @@ func makeclosure(func_ *Node) *Node {
 	func_.Func.Closure = xfunc
 
 	func_.Nbody.Set(nil)
-	func_.List = nil
-	func_.Rlist = nil
+	setNodeSeq(&func_.List, nil)
+	setNodeSeq(&func_.Rlist, nil)
 
 	return xfunc
 }
@@ -426,7 +426,7 @@ func walkclosure(func_ *Node, init nodesOrNodeListPtr) *Node {
 
 	typ := Nod(OTSTRUCT, nil, nil)
 
-	typ.List = list1(Nod(ODCLFIELD, newname(Lookup(".F")), typenod(Types[TUINTPTR])))
+	setNodeSeq(&typ.List, []*Node{Nod(ODCLFIELD, newname(Lookup(".F")), typenod(Types[TUINTPTR]))})
 	var typ1 *Node
 	for _, v := range func_.Func.Cvars.Slice() {
 		if v.Op == OXXX {
@@ -436,13 +436,13 @@ func walkclosure(func_ *Node, init nodesOrNodeListPtr) *Node {
 		if !v.Name.Byval {
 			typ1 = Nod(OIND, typ1, nil)
 		}
-		typ.List = list(typ.List, Nod(ODCLFIELD, newname(v.Sym), typ1))
+		appendNodeSeqNode(&typ.List, Nod(ODCLFIELD, newname(v.Sym), typ1))
 	}
 
 	clos := Nod(OCOMPLIT, nil, Nod(OIND, typ, nil))
 	clos.Esc = func_.Esc
 	clos.Right.Implicit = true
-	clos.List = concat(list1(Nod(OCFUNC, func_.Func.Closure.Func.Nname, nil)), func_.Func.Enter.NodeList())
+	setNodeSeq(&clos.List, append([]*Node{Nod(OCFUNC, func_.Func.Closure.Func.Nname, nil)}, func_.Func.Enter.Slice()...))
 
 	// Force type conversion from *struct to the func type.
 	clos = Nod(OCONVNOP, clos, nil)
@@ -528,8 +528,8 @@ func makepartialcall(fn *Node, t0 *Type, meth *Node) *Node {
 
 	xtype := Nod(OTFUNC, nil, nil)
 	i := 0
-	var l *NodeList
-	var callargs *NodeList
+	var l []*Node
+	var callargs []*Node
 	ddd := false
 	xfunc := Nod(ODCLFUNC, nil, nil)
 	Curfn = xfunc
@@ -540,30 +540,30 @@ func makepartialcall(fn *Node, t0 *Type, meth *Node) *Node {
 		i++
 		n.Class = PPARAM
 		xfunc.Func.Dcl = append(xfunc.Func.Dcl, n)
-		callargs = list(callargs, n)
+		callargs = append(callargs, n)
 		fld = Nod(ODCLFIELD, n, typenod(t.Type))
 		if t.Isddd {
 			fld.Isddd = true
 			ddd = true
 		}
 
-		l = list(l, fld)
+		l = append(l, fld)
 	}
 
-	xtype.List = l
+	setNodeSeq(&xtype.List, l)
 	i = 0
 	l = nil
-	var retargs *NodeList
+	var retargs []*Node
 	for t := getoutargx(t0).Type; t != nil; t = t.Down {
 		n = newname(Lookupf("r%d", i))
 		i++
 		n.Class = PPARAMOUT
 		xfunc.Func.Dcl = append(xfunc.Func.Dcl, n)
-		retargs = list(retargs, n)
-		l = list(l, Nod(ODCLFIELD, n, typenod(t.Type)))
+		retargs = append(retargs, n)
+		l = append(l, Nod(ODCLFIELD, n, typenod(t.Type)))
 	}
 
-	xtype.Rlist = l
+	setNodeSeq(&xtype.Rlist, l)
 
 	xfunc.Func.Dupok = true
 	xfunc.Func.Nname = newfuncname(sym)
@@ -600,14 +600,14 @@ func makepartialcall(fn *Node, t0 *Type, meth *Node) *Node {
 	}
 
 	call := Nod(OCALL, Nod(OXDOT, ptr, meth), nil)
-	call.List = callargs
+	setNodeSeq(&call.List, callargs)
 	call.Isddd = ddd
 	if t0.Outtuple == 0 {
 		body = append(body, call)
 	} else {
 		n := Nod(OAS2, nil, nil)
-		n.List = retargs
-		n.Rlist = list1(call)
+		setNodeSeq(&n.List, retargs)
+		setNodeSeq(&n.Rlist, []*Node{call})
 		body = append(body, n)
 		n = Nod(ORETURN, nil, nil)
 		body = append(body, n)
@@ -640,14 +640,14 @@ func walkpartialcall(n *Node, init nodesOrNodeListPtr) *Node {
 	}
 
 	typ := Nod(OTSTRUCT, nil, nil)
-	typ.List = list1(Nod(ODCLFIELD, newname(Lookup("F")), typenod(Types[TUINTPTR])))
-	typ.List = list(typ.List, Nod(ODCLFIELD, newname(Lookup("R")), typenod(n.Left.Type)))
+	setNodeSeq(&typ.List, []*Node{Nod(ODCLFIELD, newname(Lookup("F")), typenod(Types[TUINTPTR]))})
+	appendNodeSeqNode(&typ.List, Nod(ODCLFIELD, newname(Lookup("R")), typenod(n.Left.Type)))
 
 	clos := Nod(OCOMPLIT, nil, Nod(OIND, typ, nil))
 	clos.Esc = n.Esc
 	clos.Right.Implicit = true
-	clos.List = list1(Nod(OCFUNC, n.Func.Nname, nil))
-	clos.List = list(clos.List, n.Left)
+	setNodeSeq(&clos.List, []*Node{Nod(OCFUNC, n.Func.Nname, nil)})
+	appendNodeSeqNode(&clos.List, n.Left)
 
 	// Force type conversion from *struct to the func type.
 	clos = Nod(OCONVNOP, clos, nil)

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

@@ -543,39 +543,31 @@ func evconst(n *Node) {
 
 		// merge adjacent constants in the argument list.
 	case OADDSTR:
-		// TODO: We make a copy of n.List in order to abstract
-		// away the details of deleting elements.
-		// Once n.List is some kind of Node slice,
-		// re-implement using deletion.
-		var l *NodeList // replacement list
-		for l1 := n.List; l1 != nil; {
-			if !Isconst(l1.N, CTSTR) || l1.Next == nil || !Isconst(l1.Next.N, CTSTR) {
-				// non-constant string or solitary constant string
-				l = list(l, l1.N)
-				l1 = l1.Next
-				continue
+		s := nodeSeqSlice(n.List)
+		for i1 := 0; i1 < len(s); i1++ {
+			if Isconst(s[i1], CTSTR) && i1+1 < len(s) && Isconst(s[i1+1], CTSTR) {
+				// merge from i1 up to but not including i2
+				var strs []string
+				i2 := i1
+				for i2 < len(s) && Isconst(s[i2], CTSTR) {
+					strs = append(strs, s[i2].Val().U.(string))
+					i2++
+				}
+
+				nl := Nod(OXXX, nil, nil)
+				*nl = *s[i1]
+				nl.Orig = nl
+				nl.SetVal(Val{strings.Join(strs, "")})
+				s[i1] = nl
+				s = append(s[:i1+1], s[i2:]...)
 			}
-
-			first := l1.N
-
-			// merge run of constants
-			var strs []string
-			for ; l1 != nil && Isconst(l1.N, CTSTR); l1 = l1.Next {
-				strs = append(strs, l1.N.Val().U.(string))
-			}
-
-			nl := Nod(OXXX, nil, nil)
-			*nl = *first
-			nl.Orig = nl
-			nl.SetVal(Val{strings.Join(strs, "")})
-			l = list(l, nl)
 		}
-		n.List = l
 
-		// collapse single-constant list to single constant.
-		if count(n.List) == 1 && Isconst(n.List.N, CTSTR) {
+		if len(s) == 1 && Isconst(s[0], CTSTR) {
 			n.Op = OLITERAL
-			n.SetVal(n.List.N.Val())
+			n.SetVal(s[0].Val())
+		} else {
+			setNodeSeq(&n.List, s)
 		}
 
 		return
@@ -1745,13 +1737,13 @@ func hascallchan(n *Node) bool {
 		return true
 	}
 
-	for l := n.List; l != nil; l = l.Next {
-		if hascallchan(l.N) {
+	for it := nodeSeqIterate(n.List); !it.Done(); it.Next() {
+		if hascallchan(it.N()) {
 			return true
 		}
 	}
-	for l := n.Rlist; l != nil; l = l.Next {
-		if hascallchan(l.N) {
+	for it := nodeSeqIterate(n.Rlist); !it.Done(); it.Next() {
+		if hascallchan(it.N()) {
 			return true
 		}
 	}

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

@@ -437,18 +437,18 @@ func colasname(n *Node) bool {
 	return false
 }
 
-func colasdefn(left *NodeList, defn *Node) {
-	for l := left; l != nil; l = l.Next {
-		if l.N.Sym != nil {
-			l.N.Sym.Flags |= SymUniq
+func colasdefn(left nodesOrNodeList, defn *Node) {
+	for it := nodeSeqIterate(left); !it.Done(); it.Next() {
+		if it.N().Sym != nil {
+			it.N().Sym.Flags |= SymUniq
 		}
 	}
 
 	nnew := 0
 	nerr := 0
 	var n *Node
-	for l := left; l != nil; l = l.Next {
-		n = l.N
+	for it := nodeSeqIterate(left); !it.Done(); it.Next() {
+		n = it.N()
 		if isblank(n) {
 			continue
 		}
@@ -475,7 +475,7 @@ func colasdefn(left *NodeList, defn *Node) {
 		declare(n, dclcontext)
 		n.Name.Defn = defn
 		appendNodeSeqNode(&defn.Ninit, Nod(ODCL, n, nil))
-		l.N = n
+		*it.P() = n
 	}
 
 	if nnew == 0 && nerr == 0 {
@@ -828,19 +828,19 @@ func checkdupfields(t *Type, what string) {
 
 // convert a parsed id/type list into
 // a type for struct/interface/arglist
-func tostruct(l *NodeList) *Type {
+func tostruct(l nodesOrNodeList) *Type {
 	t := typ(TSTRUCT)
 	tostruct0(t, l)
 	return t
 }
 
-func tostruct0(t *Type, l *NodeList) {
+func tostruct0(t *Type, l nodesOrNodeList) {
 	if t == nil || t.Etype != TSTRUCT {
 		Fatalf("struct expected")
 	}
 
-	for tp := &t.Type; l != nil; l = l.Next {
-		f := structfield(l.N)
+	for tp, it := &t.Type, nodeSeqIterate(l); !it.Done(); it.Next() {
+		f := structfield(it.N())
 
 		*tp = f
 		tp = &f.Down
@@ -860,19 +860,19 @@ func tostruct0(t *Type, l *NodeList) {
 	}
 }
 
-func tofunargs(l *NodeList) *Type {
+func tofunargs(l nodesOrNodeList) *Type {
 	var f *Type
 
 	t := typ(TSTRUCT)
 	t.Funarg = true
 
-	for tp := &t.Type; l != nil; l = l.Next {
-		f = structfield(l.N)
+	for tp, it := &t.Type, nodeSeqIterate(l); !it.Done(); it.Next() {
+		f = structfield(it.N())
 		f.Funarg = true
 
 		// esc.go needs to find f given a PPARAM to add the tag.
-		if l.N.Left != nil && l.N.Left.Class == PPARAM {
-			l.N.Left.Name.Param.Field = f
+		if it.N().Left != nil && it.N().Left.Class == PPARAM {
+			it.N().Left.Name.Param.Field = f
 		}
 
 		*tp = f
@@ -955,22 +955,22 @@ func interfacefield(n *Node) *Type {
 	return f
 }
 
-func tointerface(l *NodeList) *Type {
+func tointerface(l nodesOrNodeList) *Type {
 	t := typ(TINTER)
 	tointerface0(t, l)
 	return t
 }
 
-func tointerface0(t *Type, l *NodeList) *Type {
+func tointerface0(t *Type, l nodesOrNodeList) *Type {
 	if t == nil || t.Etype != TINTER {
 		Fatalf("interface expected")
 	}
 
 	tp := &t.Type
-	for ; l != nil; l = l.Next {
-		f := interfacefield(l.N)
+	for it := nodeSeqIterate(l); !it.Done(); it.Next() {
+		f := interfacefield(it.N())
 
-		if l.N.Left == nil && f.Type.Etype == TINTER {
+		if it.N().Left == nil && f.Type.Etype == TINTER {
 			// embedded interface, inline methods
 			for t1 := f.Type.Type; t1 != nil; t1 = t1.Down {
 				f = typ(TFIELD)
@@ -1155,13 +1155,13 @@ func isifacemethod(f *Type) bool {
 }
 
 // turn a parsed function declaration into a type
-func functype(this *Node, in *NodeList, out *NodeList) *Type {
+func functype(this *Node, in nodesOrNodeList, out nodesOrNodeList) *Type {
 	t := typ(TFUNC)
 	functype0(t, this, in, out)
 	return t
 }
 
-func functype0(t *Type, this *Node, in *NodeList, out *NodeList) {
+func functype0(t *Type, this *Node, in nodesOrNodeList, out nodesOrNodeList) {
 	if t == nil || t.Etype != TFUNC {
 		Fatalf("function type expected")
 	}
@@ -1186,11 +1186,11 @@ func functype0(t *Type, this *Node, in *NodeList, out *NodeList) {
 	if this != nil {
 		t.Thistuple = 1
 	}
-	t.Outtuple = count(out)
-	t.Intuple = count(in)
+	t.Outtuple = nodeSeqLen(out)
+	t.Intuple = nodeSeqLen(in)
 	t.Outnamed = false
-	if t.Outtuple > 0 && out.N.Left != nil && out.N.Left.Orig != nil {
-		s := out.N.Left.Orig.Sym
+	if t.Outtuple > 0 && nodeSeqFirst(out).Left != nil && nodeSeqFirst(out).Left.Orig != nil {
+		s := nodeSeqFirst(out).Left.Orig.Sym
 		if s != nil && (s.Name[0] != '~' || s.Name[1] != 'r') { // ~r%d is the name invented for an unnamed result
 			t.Outnamed = true
 		}

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

@@ -771,12 +771,12 @@ func esc(e *EscState, n *Node, up *Node) {
 		}
 
 	case ORETURN:
-		ll := n.List
+		ll := nodesOrNodeList(n.List)
 		if nodeSeqLen(n.List) == 1 && Curfn.Type.Outtuple > 1 {
 			// OAS2FUNC in disguise
 			// esccall already done on n->list->n
 			// tie n->list->n->escretval to curfn->dcl PPARAMOUT's
-			ll = e.nodeEscState(n.List.N).Escretval
+			ll = e.nodeEscState(nodeSeqFirst(n.List)).Escretval
 		}
 
 		llit := nodeSeqIterate(ll)
@@ -1368,9 +1368,9 @@ func esccall(e *EscState, n *Node, up *Node) {
 		indirect = true
 	}
 
-	ll := n.List
-	if n.List != nil && n.List.Next == nil {
-		a := n.List.N
+	ll := nodesOrNodeList(n.List)
+	if nodeSeqLen(n.List) == 1 {
+		a := nodeSeqFirst(n.List)
 		if a.Type.Etype == TSTRUCT && a.Type.Funarg { // f(g()).
 			ll = e.nodeEscState(a).Escretval
 		}
@@ -1481,15 +1481,16 @@ func esccall(e *EscState, n *Node, up *Node) {
 	}
 
 	var src *Node
-	for t := getinargx(fntype).Type; ll != nil; ll = ll.Next {
-		src = ll.N
+	it := nodeSeqIterate(ll)
+	for t := getinargx(fntype).Type; !it.Done(); it.Next() {
+		src = it.N()
 		if t.Isddd && !n.Isddd {
 			// Introduce ODDDARG node to represent ... allocation.
 			src = Nod(ODDDARG, nil, nil)
 			src.Lineno = n.Lineno
 			src.Type = typ(TARRAY)
 			src.Type.Type = t.Type.Type
-			src.Type.Bound = int64(count(ll))
+			src.Type.Bound = int64(it.Len())
 			src.Type = Ptrto(src.Type) // make pointer so it will be tracked
 			e.track(src)
 			n.Right = src
@@ -1522,18 +1523,18 @@ func esccall(e *EscState, n *Node, up *Node) {
 			}
 		}
 
-		if src != ll.N {
+		if src != it.N() {
 			// This occurs when function parameter type Isddd and n not Isddd
 			break
 		}
 		t = t.Down
 	}
 
-	for ; ll != nil; ll = ll.Next {
+	for ; !it.Done(); it.Next() {
 		if Debug['m'] > 2 {
-			fmt.Printf("%v::esccall:: ... <- %v\n", linestr(lineno), Nconv(ll.N, obj.FmtShort))
+			fmt.Printf("%v::esccall:: ... <- %v\n", linestr(lineno), Nconv(it.N(), obj.FmtShort))
 		}
-		escassign(e, src, ll.N) // args to slice
+		escassign(e, src, it.N()) // args to slice
 	}
 }
 

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

@@ -885,7 +885,7 @@ func stmtfmt(n *Node) string {
 
 	case OIF:
 		if simpleinit {
-			f += fmt.Sprintf("if %v; %v { %v }", n.Ninit.N, n.Left, n.Nbody)
+			f += fmt.Sprintf("if %v; %v { %v }", nodeSeqFirst(n.Ninit), n.Left, n.Nbody)
 		} else {
 			f += fmt.Sprintf("if %v { %v }", n.Left, n.Nbody)
 		}

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

@@ -670,7 +670,7 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 	as = Nod(OAS2, nil, nil)
 
 	setNodeSeq(&as.Rlist, n.List)
-	ll := n.List
+	it := nodeSeqIterate(n.List)
 
 	// TODO: if len(nlist) == 1 but multiple args, check that n->list->n is a call?
 	if fn.Type.Thistuple != 0 && n.Left.Op != ODOTMETH {
@@ -689,7 +689,7 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 			Fatalf("method call unknown receiver type: %v", Nconv(n, obj.FmtSign))
 		}
 		appendNodeSeqNode(&as.List, tinlvar(t))
-		ll = ll.Next // track argument count.
+		it.Next() // track argument count.
 	}
 
 	// append ordinary arguments to LHS.
@@ -703,7 +703,7 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 		for t := getinargx(fn.Type).Type; t != nil; t = t.Down {
 			if variadic && t.Isddd {
 				vararg = tinlvar(t)
-				for i = 0; i < varargcount && ll != nil; i++ {
+				for i = 0; i < varargcount && it.Len() != 0; i++ {
 					m = argvar(varargtype, i)
 					varargs = append(varargs, m)
 					appendNodeSeqNode(&as.List, m)
@@ -718,7 +718,7 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 		// match arguments except final variadic (unless the call is dotted itself)
 		var t *Type
 		for t = getinargx(fn.Type).Type; t != nil; {
-			if ll == nil {
+			if it.Done() {
 				break
 			}
 			if variadic && t.Isddd {
@@ -726,18 +726,18 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 			}
 			appendNodeSeqNode(&as.List, tinlvar(t))
 			t = t.Down
-			ll = ll.Next
+			it.Next()
 		}
 
 		// match varargcount arguments with variadic parameters.
 		if variadic && t != nil && t.Isddd {
 			vararg = tinlvar(t)
 			var i int
-			for i = 0; i < varargcount && ll != nil; i++ {
+			for i = 0; i < varargcount && !it.Done(); i++ {
 				m = argvar(varargtype, i)
 				varargs = append(varargs, m)
 				appendNodeSeqNode(&as.List, m)
-				ll = ll.Next
+				it.Next()
 			}
 
 			if i == varargcount {
@@ -745,7 +745,7 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 			}
 		}
 
-		if ll != nil || t != nil {
+		if !it.Done() || t != nil {
 			Fatalf("arg count mismatch: %v  vs %v\n", Tconv(getinargx(fn.Type), obj.FmtSharp), Hconv(n.List, obj.FmtComma))
 		}
 	}

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

@@ -255,18 +255,14 @@ func orderstmtlist(l nodesOrNodeList, order *Order) {
 	}
 }
 
-// Orderblock orders the block of statements *l onto a new list,
-// and then replaces *l with that list.
-func orderblock(l **NodeList) {
+// Orderblock orders the block of statements l onto a new list,
+// and returns the ordered list.
+func orderblock(l nodesOrNodeList) []*Node {
 	var order Order
 	mark := marktemp(&order)
-	orderstmtlist(*l, &order)
+	orderstmtlist(l, &order)
 	cleantemp(mark, &order)
-	var ll *NodeList
-	for _, n := range order.out {
-		ll = list(ll, n)
-	}
-	*l = ll
+	return order.out
 }
 
 // OrderblockNodes orders the block of statements in n into a new slice,
@@ -313,12 +309,12 @@ func orderinit(n *Node, order *Order) {
 
 // Ismulticall reports whether the list l is f() for a multi-value function.
 // Such an f() could appear as the lone argument to a multi-arg function.
-func ismulticall(l *NodeList) bool {
+func ismulticall(l nodesOrNodeList) bool {
 	// one arg only
-	if l == nil || l.Next != nil {
+	if nodeSeqLen(l) != 1 {
 		return false
 	}
-	n := l.N
+	n := nodeSeqFirst(l)
 
 	// must be call
 	switch n.Op {
@@ -359,13 +355,15 @@ func copyret(n *Node, order *Order) *NodeList {
 	return l2
 }
 
-// Ordercallargs orders the list of call arguments *l.
-func ordercallargs(l **NodeList, order *Order) {
-	if ismulticall(*l) {
+// Ordercallargs orders the list of call arguments l and returns the
+// ordered list.
+func ordercallargs(l nodesOrNodeList, order *Order) nodesOrNodeList {
+	if ismulticall(l) {
 		// return f() where f() is multiple values.
-		*l = copyret((*l).N, order)
+		return copyret(nodeSeqFirst(l), order)
 	} else {
-		orderexprlist(*l, order)
+		orderexprlist(l, order)
+		return l
 	}
 }
 
@@ -374,7 +372,7 @@ func ordercallargs(l **NodeList, order *Order) {
 func ordercall(n *Node, order *Order) {
 	orderexpr(&n.Left, order, nil)
 	orderexpr(&n.Right, order, nil) // ODDDARG temp
-	ordercallargs(&n.List, order)
+	setNodeSeq(&n.List, ordercallargs(n.List, order))
 
 	if n.Op == OCALLFUNC {
 		t := getinargx(n.Left.Type).Type
@@ -704,7 +702,7 @@ func orderstmt(n *Node, order *Order) {
 		setNodeSeq(&n.Rlist, append(l, nodeSeqSlice(n.Rlist)...))
 		poptemp(t, order)
 		orderblockNodes(&n.Nbody)
-		orderblock(&n.Rlist)
+		setNodeSeq(&n.Rlist, orderblock(n.Rlist))
 		order.out = append(order.out, n)
 
 		// Special: argument will be converted to interface using convT2E
@@ -782,7 +780,7 @@ func orderstmt(n *Node, order *Order) {
 		cleantemp(t, order)
 
 	case ORETURN:
-		ordercallargs(&n.List, order)
+		setNodeSeq(&n.List, ordercallargs(n.List, order))
 		order.out = append(order.out, n)
 
 	// Special: clean case temporaries in each block entry.
@@ -896,7 +894,7 @@ func orderstmt(n *Node, order *Order) {
 						appendNodeSeqNode(&it.N().Ninit, tmp2)
 					}
 
-					orderblock(&it.N().Ninit)
+					setNodeSeq(&it.N().Ninit, orderblock(it.N().Ninit))
 
 				case OSEND:
 					if nodeSeqLen(r.Ninit) != 0 {
@@ -971,17 +969,17 @@ func orderstmt(n *Node, order *Order) {
 }
 
 // Orderexprlist orders the expression list l into order.
-func orderexprlist(l *NodeList, order *Order) {
-	for ; l != nil; l = l.Next {
-		orderexpr(&l.N, order, nil)
+func orderexprlist(l nodesOrNodeList, order *Order) {
+	for it := nodeSeqIterate(l); !it.Done(); it.Next() {
+		orderexpr(it.P(), order, nil)
 	}
 }
 
 // Orderexprlist orders the expression list l but saves
 // the side effects on the individual expression ninit lists.
-func orderexprlistinplace(l *NodeList, order *Order) {
-	for ; l != nil; l = l.Next {
-		orderexprinplace(&l.N, order)
+func orderexprlistinplace(l nodesOrNodeList, order *Order) {
+	for it := nodeSeqIterate(l); !it.Done(); it.Next() {
+		orderexprinplace(it.P(), order)
 	}
 }
 
@@ -1131,7 +1129,7 @@ func orderexpr(np **Node, order *Order, lhs *Node) {
 		}
 
 	case OAPPEND:
-		ordercallargs(&n.List, order)
+		setNodeSeq(&n.List, ordercallargs(n.List, order))
 		if lhs == nil || lhs.Op != ONAME && !samesafeexpr(lhs, nodeSeqFirst(n.List)) {
 			n = ordercopyexpr(n, n.Type, order, 0)
 		}

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

@@ -240,7 +240,7 @@ func walkselect(sel *Node) {
 
 			setNodeSeq(&r.Ninit, cas.Ninit)
 			ch := n.Right.Left
-			r.Left = mkcall1(chanfn("selectnbrecv2", 2, ch.Type), Types[TBOOL], &r.Ninit, typename(ch.Type), n.Left, n.List.N, ch)
+			r.Left = mkcall1(chanfn("selectnbrecv2", 2, ch.Type), Types[TBOOL], &r.Ninit, typename(ch.Type), n.Left, nodeSeqFirst(n.List), ch)
 		}
 
 		typecheck(&r.Left, Erv)

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

@@ -587,7 +587,8 @@ func (ni *nodesIterator) Seq() nodesOrNodeList {
 	return r
 }
 
-// nodeSeqIterate returns an iterator over a *NodeList, a Nodes, or a []*Node.
+// nodeSeqIterate returns an iterator over a *NodeList, a Nodes,
+// a []*Node, or nil.
 func nodeSeqIterate(ns nodesOrNodeList) nodeSeqIterator {
 	switch ns := ns.(type) {
 	case *NodeList:
@@ -598,12 +599,15 @@ func nodeSeqIterate(ns nodesOrNodeList) nodeSeqIterator {
 		var r Nodes
 		r.Set(ns)
 		return &nodesIterator{r, 0}
+	case nil:
+		var r Nodes
+		return &nodesIterator{r, 0}
 	default:
 		panic("can't happen")
 	}
 }
 
-// nodeSeqLen returns the length of a *NodeList, a Nodes, or a []*Node.
+// nodeSeqLen returns the length of a *NodeList, a Nodes, a []*Node, or nil.
 func nodeSeqLen(ns nodesOrNodeList) int {
 	switch ns := ns.(type) {
 	case *NodeList:
@@ -612,6 +616,8 @@ func nodeSeqLen(ns nodesOrNodeList) int {
 		return len(ns.Slice())
 	case []*Node:
 		return len(ns)
+	case nil:
+		return 0
 	default:
 		panic("can't happen")
 	}

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

@@ -1671,7 +1671,7 @@ OpSwitch:
 	case OCOPY:
 		ok |= Etop | Erv
 		args := n.List
-		if nodeSeqLen(args) == 0 || args.Next == nil {
+		if nodeSeqLen(args) < 2 {
 			Yyerror("missing arguments to copy")
 			n.Type = nil
 			return
@@ -2575,9 +2575,9 @@ func lookdot(n *Node, t *Type, dostrcmp int) *Type {
 	return nil
 }
 
-func nokeys(l *NodeList) bool {
-	for ; l != nil; l = l.Next {
-		if l.N.Op == OKEY {
+func nokeys(l nodesOrNodeList) bool {
+	for it := nodeSeqIterate(l); !it.Done(); it.Next() {
+		if it.N().Op == OKEY {
 			return false
 		}
 	}
@@ -2606,11 +2606,12 @@ func downcount(t *Type) int {
 }
 
 // typecheck assignment: type list = expression list
-func typecheckaste(op Op, call *Node, isddd bool, tstruct *Type, nl *NodeList, desc func() string) {
+func typecheckaste(op Op, call *Node, isddd bool, tstruct *Type, nl nodesOrNodeList, desc func() string) {
 	var t *Type
 	var n *Node
 	var n1 int
 	var n2 int
+	var it nodeSeqIterator
 
 	lno := lineno
 
@@ -2619,8 +2620,8 @@ func typecheckaste(op Op, call *Node, isddd bool, tstruct *Type, nl *NodeList, d
 	}
 
 	n = nil
-	if nl != nil && nl.Next == nil {
-		n = nl.N
+	if nodeSeqLen(nl) == 1 {
+		n = nodeSeqFirst(nl)
 		if n.Type != nil {
 			if n.Type.Etype == TSTRUCT && n.Type.Funarg {
 				if !hasddd(tstruct) {
@@ -2674,7 +2675,7 @@ func typecheckaste(op Op, call *Node, isddd bool, tstruct *Type, nl *NodeList, d
 	}
 
 	n1 = downcount(tstruct)
-	n2 = count(nl)
+	n2 = nodeSeqLen(nl)
 	if !hasddd(tstruct) {
 		if n2 > n1 {
 			goto toomany
@@ -2697,47 +2698,48 @@ func typecheckaste(op Op, call *Node, isddd bool, tstruct *Type, nl *NodeList, d
 		}
 	}
 
+	it = nodeSeqIterate(nl)
 	for tl := tstruct.Type; tl != nil; tl = tl.Down {
 		t = tl.Type
 		if tl.Isddd {
 			if isddd {
-				if nl == nil {
+				if it.Done() {
 					goto notenough
 				}
-				if nl.Next != nil {
+				if it.Len() > 1 {
 					goto toomany
 				}
-				n = nl.N
+				n = it.N()
 				setlineno(n)
 				if n.Type != nil {
-					nl.N = assignconvfn(n, t, desc)
+					*it.P() = assignconvfn(n, t, desc)
 				}
 				goto out
 			}
 
-			for ; nl != nil; nl = nl.Next {
-				n = nl.N
-				setlineno(nl.N)
+			for ; !it.Done(); it.Next() {
+				n = it.N()
+				setlineno(it.N())
 				if n.Type != nil {
-					nl.N = assignconvfn(n, t.Type, desc)
+					*it.P() = assignconvfn(n, t.Type, desc)
 				}
 			}
 
 			goto out
 		}
 
-		if nl == nil {
+		if it.Done() {
 			goto notenough
 		}
-		n = nl.N
+		n = it.N()
 		setlineno(n)
 		if n.Type != nil {
-			nl.N = assignconvfn(n, t, desc)
+			*it.P() = assignconvfn(n, t, desc)
 		}
-		nl = nl.Next
+		it.Next()
 	}
 
-	if nl != nil {
+	if !it.Done() {
 		goto toomany
 	}
 	if isddd {
@@ -3233,9 +3235,9 @@ func checkassign(stmt *Node, n *Node) {
 	Yyerror("cannot assign to %v", n)
 }
 
-func checkassignlist(stmt *Node, l *NodeList) {
-	for ; l != nil; l = l.Next {
-		checkassign(stmt, l.N)
+func checkassignlist(stmt *Node, l nodesOrNodeList) {
+	for it := nodeSeqIterate(l); !it.Done(); it.Next() {
+		checkassign(stmt, it.N())
 	}
 }
 

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

@@ -26,12 +26,12 @@ func unsafenmagic(nn *Node) *Node {
 		return nil
 	}
 
-	if args == nil {
+	if nodeSeqLen(args) == 0 {
 		Yyerror("missing argument for %v", s)
 		return nil
 	}
 
-	r := args.N
+	r := nodeSeqFirst(args)
 
 	var v int64
 	if s.Name == "Sizeof" {
@@ -129,7 +129,7 @@ bad:
 	goto ret
 
 yes:
-	if args.Next != nil {
+	if nodeSeqLen(args) > 1 {
 		Yyerror("extra arguments for %v", s)
 	}
 

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

@@ -89,13 +89,17 @@ func walkstmtslice(l []*Node) {
 	}
 }
 
-func samelist(a *NodeList, b *NodeList) bool {
-	for ; a != nil && b != nil; a, b = a.Next, b.Next {
-		if a.N != b.N {
+func samelist(a nodesOrNodeList, b nodesOrNodeList) bool {
+	ita := nodeSeqIterate(a)
+	itb := nodeSeqIterate(b)
+	for !ita.Done() && !itb.Done() {
+		if ita.N() != itb.N() {
 			return false
 		}
+		ita.Next()
+		itb.Next()
 	}
-	return a == b
+	return ita.Done() == itb.Done()
 }
 
 func paramoutheap(fn *Node) bool {
@@ -651,7 +655,7 @@ opswitch:
 			// transformclosure already did all preparation work.
 
 			// Prepend captured variables to argument list.
-			setNodeSeq(&n.List, concat(n.Left.Func.Enter.NodeList(), n.List))
+			setNodeSeq(&n.List, append(n.Left.Func.Enter.Slice(), nodeSeqSlice(n.List)...))
 
 			n.Left.Func.Enter.Set(nil)
 
@@ -1659,33 +1663,35 @@ func ascompatee1(op Op, l *Node, r *Node, init nodesOrNodeListPtr) *Node {
 	return convas(n, init)
 }
 
-func ascompatee(op Op, nl *NodeList, nr *NodeList, init nodesOrNodeListPtr) *NodeList {
+func ascompatee(op Op, nl nodesOrNodeList, nr nodesOrNodeList, init nodesOrNodeListPtr) *NodeList {
 	// check assign expression list to
 	// a expression list. called in
 	//	expr-list = expr-list
 
 	// ensure order of evaluation for function calls
-	for ll := nl; ll != nil; ll = ll.Next {
-		ll.N = safeexpr(ll.N, init)
+	for nlit := nodeSeqIterate(nl); !nlit.Done(); nlit.Next() {
+		*nlit.P() = safeexpr(nlit.N(), init)
 	}
-	for lr := nr; lr != nil; lr = lr.Next {
-		lr.N = safeexpr(lr.N, init)
+	for nrit := nodeSeqIterate(nr); !nrit.Done(); nrit.Next() {
+		*nrit.P() = safeexpr(nrit.N(), init)
 	}
 
 	var nn *NodeList
-	ll := nl
-	lr := nr
-	for ; ll != nil && lr != nil; ll, lr = ll.Next, lr.Next {
+	nlit := nodeSeqIterate(nl)
+	nrit := nodeSeqIterate(nr)
+	for ; !nlit.Done() && !nrit.Done(); nlit.Next() {
 		// Do not generate 'x = x' during return. See issue 4014.
-		if op == ORETURN && ll.N == lr.N {
+		if op == ORETURN && nlit.N() == nrit.N() {
+			nrit.Next()
 			continue
 		}
-		nn = list(nn, ascompatee1(op, ll.N, lr.N, init))
+		nn = list(nn, ascompatee1(op, nlit.N(), nrit.N(), init))
+		nrit.Next()
 	}
 
 	// cannot happen: caller checked that lists had same length
-	if ll != nil || lr != nil {
-		Yyerror("error in shape across %v %v %v / %d %d [%s]", Hconv(nl, obj.FmtSign), Oconv(op, 0), Hconv(nr, obj.FmtSign), count(nl), count(nr), Curfn.Func.Nname.Sym.Name)
+	if !nlit.Done() || !nrit.Done() {
+		Yyerror("error in shape across %v %v %v / %d %d [%s]", Hconv(nl, obj.FmtSign), Oconv(op, 0), Hconv(nr, obj.FmtSign), nodeSeqLen(nl), nodeSeqLen(nr), Curfn.Func.Nname.Sym.Name)
 	}
 	return nn
 }
@@ -1708,11 +1714,10 @@ func fncall(l *Node, rt *Type) bool {
 	return true
 }
 
-func ascompatet(op Op, nl *NodeList, nr **Type, fp int, init nodesOrNodeListPtr) *NodeList {
+func ascompatet(op Op, nl nodesOrNodeList, nr **Type, fp int, init nodesOrNodeListPtr) *NodeList {
 	var l *Node
 	var tmp *Node
 	var a *Node
-	var ll *NodeList
 	var saver Iter
 
 	// check assign type list to
@@ -1723,11 +1728,12 @@ func ascompatet(op Op, nl *NodeList, nr **Type, fp int, init nodesOrNodeListPtr)
 	var nn *NodeList
 	var mm *NodeList
 	ucount := 0
-	for ll = nl; ll != nil; ll = ll.Next {
+	it := nodeSeqIterate(nl)
+	for ; !it.Done(); it.Next() {
 		if r == nil {
 			break
 		}
-		l = ll.N
+		l = it.N()
 		if isblank(l) {
 			r = structnext(&saver)
 			continue
@@ -1757,8 +1763,8 @@ func ascompatet(op Op, nl *NodeList, nr **Type, fp int, init nodesOrNodeListPtr)
 		r = structnext(&saver)
 	}
 
-	if ll != nil || r != nil {
-		Yyerror("ascompatet: assignment count mismatch: %d = %d", count(nl), structcount(*nr))
+	if !it.Done() || r != nil {
+		Yyerror("ascompatet: assignment count mismatch: %d = %d", nodeSeqLen(nl), structcount(*nr))
 	}
 
 	if ucount != 0 {
@@ -2947,7 +2953,7 @@ func appendslice(n *Node, init nodesOrNodeListPtr) *Node {
 //   }
 //   s
 func walkappend(n *Node, init nodesOrNodeListPtr, dst *Node) *Node {
-	if !samesafeexpr(dst, n.List.N) {
+	if !samesafeexpr(dst, nodeSeqFirst(n.List)) {
 		it := nodeSeqIterate(n.List)
 		*it.P() = safeexpr(it.N(), init)
 		walkexpr(it.P(), init)