if got := err.msg(); got != want {
		t.Errorf("empty error: got %q, want %q", got, want)
	}

	want = "foo 42"
	err.addf(noposn, "foo %d", 42)
	if got := err.msg(); got != want {
		t.Errorf("simple error: got %q, want %q", got, want)
	}

	want = "foo 42\n\tbar 43"
	err.addf(noposn, "bar %d", 43)
	if got := err.msg(); got != want {
		t.Errorf("simple error: got %q, want %q", got, want)
	}
}

						fun := &ast.SelectorExpr{X: newIdent(pos, "posn"), Sel: newIdent(pos, "Pos")}
						arg := &ast.CallExpr{Fun: fun, Lparen: pos, Args: nil, Ellipsis: token.NoPos, Rparen: pos}
						n.Args[0] = arg
						return false
					}
				case "addf":
					// rewrite err.addf(pos, ...) to err.addf(posn, ...)
					if isIdent(n.Args[0], "pos") {
						pos := n.Args[0].Pos()
						arg := newIdent(pos, "posn")
						n.Args[0] = arg

	case ast.Node:
		pos := x.Pos()
		return posSpan{pos, pos, x.End()}
	case *operand:
		if x.expr != nil {
			pos := x.Pos()
			return posSpan{pos, pos, x.expr.End()}
		}
		return posSpan{nopos, nopos, nopos}
	default:
		pos := at.Pos()
		return posSpan{pos, pos, pos}
	}

	} else if r > 0 {
		at = rhs[r-1] // report at last value
	}
	err := check.newError(WrongResultCount)
	err.addf(at, "%s return values", qualifier)
	err.addf(noposn, "have %s", check.typesSummary(operandTypes(rhs), false))
	err.addf(noposn, "want %s", check.typesSummary(varTypes(lhs), false))
	err.report()
}

// initVars type-checks assignments of initialization expressions orig_rhs
// to variables lhs.

package types

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"internal/godebug"
	. "internal/types/errors"
	"strings"
	"sync/atomic"
)

// nopos, noposn indicate an unknown position
var nopos token.Pos
var noposn = atPos(nopos)

// debugging/development support
const debug = false // leave on during development

// gotypesalias controls the use of Alias types.

		if sig.params != nil {
			params = sig.params.vars
		}
		err := check.newError(WrongArgCount)
		err.addf(at, "%s arguments in call to %s", qualifier, call.Fun)
		err.addf(noposn, "have %s", check.typesSummary(operandTypes(args), false))
		err.addf(noposn, "want %s", check.typesSummary(varTypes(params), sig.variadic))
		err.report()
		return
	}

	// collect type parameters of callee and generic function arguments

func TestNoXPos(t *testing.T) {
	var tab PosTable
	if tab.Pos(NoXPos) != NoPos {
		t.Errorf("failed to translate NoXPos to Pos using zero PosTable")
	}
}

func TestConversion(t *testing.T) {
	b1 := NewFileBase("b1", "b1")
	b2 := NewFileBase("b2", "b2")
	b3 := NewLinePragmaBase(MakePos(b1, 10, 0), "b3", "b3", 123, 0)

	var tab PosTable
	for _, want := range []Pos{
		NoPos,
		MakePos(nil, 0, 0), // same table entry as NoPos

	}

	// various other types
	pkg := NewPackage("p", "p")
	t1 := NewTypeName(nopos, pkg, "t1", nil)
	n1 := NewNamed(t1, new(Struct), nil)
	t5 := NewTypeName(nopos, pkg, "t5", nil)
	NewTypeParam(t5, nil)
	for _, test := range []struct {
		name  *TypeName
		alias bool
	}{
		{NewTypeName(nopos, nil, "t0", nil), false}, // no type yet
		{NewTypeName(nopos, pkg, "t0", nil), false}, // no type yet

	}

	// various other types
	pkg := NewPackage("p", "p")
	t1 := NewTypeName(nopos, pkg, "t1", nil)
	n1 := NewNamed(t1, new(Struct), nil)
	t5 := NewTypeName(nopos, pkg, "t5", nil)
	NewTypeParam(t5, nil)
	for _, test := range []struct {
		name  *TypeName
		alias bool
	}{
		{NewTypeName(nopos, nil, "t0", nil), false}, // no type yet
		{NewTypeName(nopos, pkg, "t0", nil), false}, // no type yet

		recv := NewVar(nopos, nil, "", typ)
		res := NewVar(nopos, nil, "", Typ[String])
		sig := NewSignatureType(recv, nil, nil, nil, NewTuple(res), false)
		err := NewFunc(nopos, nil, "Error", sig)

		// interface{ Error() string }
		ityp := &Interface{methods: []*Func{err}, complete: true}
		computeInterfaceTypeSet(nil, nopos, ityp) // prevent races due to lazy computation of tset

		typ.SetUnderlying(ityp)
		def(obj)