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[dev.regabi] go/types: consistently report nil type as "untyped nil"

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This is a port of CL 284052 to go/types. The port is not entirely
faithful, as untyped conversion has been refactored in go/types.
Additionally, a comment was added to reference issue #13061 in the
implicitType method.

For #13061

Change-Id: Iec17611f6432c988624023d1d74121ff34eb0c83
Reviewed-on: https://go-review.googlesource.com/c/go/+/289715
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley 2021-02-04 11:44:21 -05:00 committed by Robert Findley
parent 50449de66a
commit 618e3c15bd
3 changed files with 59 additions and 11 deletions
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64
src/go/types/api_test.go
View File

@ -42,7 +42,7 @@ func mustTypecheck(t *testing.T, path, source string, info *Info) string {
return pkg.Name()
}
func mayTypecheck(t *testing.T, path, source string, info *Info) string {
func mayTypecheck(t *testing.T, path, source string, info *Info) (string, error) {
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, path, source, 0)
if f == nil { // ignore errors unless f is nil
@ -52,8 +52,8 @@ func mayTypecheck(t *testing.T, path, source string, info *Info) string {
Error: func(err error) {},
Importer: importer.Default(),
}
pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
return pkg.Name()
pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
return pkg.Name(), err
}
func TestValuesInfo(t *testing.T) {
@ -175,6 +175,9 @@ func TestValuesInfo(t *testing.T) {
}
func TestTypesInfo(t *testing.T) {
// Test sources that are not expected to typecheck must start with the broken prefix.
const broken = "package broken_"
var tests = []struct {
src string
expr string // expression
@ -187,6 +190,39 @@ func TestTypesInfo(t *testing.T) {
{`package b3; var x interface{} = 0i`, `0i`, `complex128`},
{`package b4; var x interface{} = "foo"`, `"foo"`, `string`},
// uses of nil
{`package n0; var _ *int = nil`, `nil`, `untyped nil`},
{`package n1; var _ func() = nil`, `nil`, `untyped nil`},
{`package n2; var _ []byte = nil`, `nil`, `untyped nil`},
{`package n3; var _ map[int]int = nil`, `nil`, `untyped nil`},
{`package n4; var _ chan int = nil`, `nil`, `untyped nil`},
{`package n5; var _ interface{} = nil`, `nil`, `untyped nil`},
{`package n6; import "unsafe"; var _ unsafe.Pointer = nil`, `nil`, `untyped nil`},
{`package n10; var (x *int; _ = x == nil)`, `nil`, `untyped nil`},
{`package n11; var (x func(); _ = x == nil)`, `nil`, `untyped nil`},
{`package n12; var (x []byte; _ = x == nil)`, `nil`, `untyped nil`},
{`package n13; var (x map[int]int; _ = x == nil)`, `nil`, `untyped nil`},
{`package n14; var (x chan int; _ = x == nil)`, `nil`, `untyped nil`},
{`package n15; var (x interface{}; _ = x == nil)`, `nil`, `untyped nil`},
{`package n15; import "unsafe"; var (x unsafe.Pointer; _ = x == nil)`, `nil`, `untyped nil`},
{`package n20; var _ = (*int)(nil)`, `nil`, `untyped nil`},
{`package n21; var _ = (func())(nil)`, `nil`, `untyped nil`},
{`package n22; var _ = ([]byte)(nil)`, `nil`, `untyped nil`},
{`package n23; var _ = (map[int]int)(nil)`, `nil`, `untyped nil`},
{`package n24; var _ = (chan int)(nil)`, `nil`, `untyped nil`},
{`package n25; var _ = (interface{})(nil)`, `nil`, `untyped nil`},
{`package n26; import "unsafe"; var _ = unsafe.Pointer(nil)`, `nil`, `untyped nil`},
{`package n30; func f(*int) { f(nil) }`, `nil`, `untyped nil`},
{`package n31; func f(func()) { f(nil) }`, `nil`, `untyped nil`},
{`package n32; func f([]byte) { f(nil) }`, `nil`, `untyped nil`},
{`package n33; func f(map[int]int) { f(nil) }`, `nil`, `untyped nil`},
{`package n34; func f(chan int) { f(nil) }`, `nil`, `untyped nil`},
{`package n35; func f(interface{}) { f(nil) }`, `nil`, `untyped nil`},
{`package n35; import "unsafe"; func f(unsafe.Pointer) { f(nil) }`, `nil`, `untyped nil`},
// comma-ok expressions
{`package p0; var x interface{}; var _, _ = x.(int)`,
`x.(int)`,
@ -268,17 +304,27 @@ func TestTypesInfo(t *testing.T) {
},
// tests for broken code that doesn't parse or type-check
{`package x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
{`package x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},
{`package x2; func _() { var a, b string; type x struct {f string}; z := &x{f: a; f: b;}}`, `b`, `string`},
{`package x3; var x = panic("");`, `panic`, `func(interface{})`},
{broken + `x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
{broken + `x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},
{broken + `x2; func _() { var a, b string; type x struct {f string}; z := &x{f: a; f: b;}}`, `b`, `string`},
{broken + `x3; var x = panic("");`, `panic`, `func(interface{})`},
{`package x4; func _() { panic("") }`, `panic`, `func(interface{})`},
{`package x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string][-1]int`},
{broken + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string][-1]int`},
}
for _, test := range tests {
info := Info{Types: make(map[ast.Expr]TypeAndValue)}
name := mayTypecheck(t, "TypesInfo", test.src, &info)
var name string
if strings.HasPrefix(test.src, broken) {
var err error
name, err = mayTypecheck(t, "TypesInfo", test.src, &info)
if err == nil {
t.Errorf("package %s: expected to fail but passed", name)
continue
}
} else {
name = mustTypecheck(t, "TypesInfo", test.src, &info)
}
// look for expression type
var typ Type

4
src/go/types/conversions.go
View File

@ -55,8 +55,8 @@ func (check *Checker) conversion(x *operand, T Type) {
// - Keep untyped nil for untyped nil arguments.
// - For integer to string conversions, keep the argument type.
// (See also the TODO below.)
if IsInterface(T) || constArg && !isConstType(T) {
final = Default(x.typ)
if IsInterface(T) || constArg && !isConstType(T) || x.isNil() {
final = Default(x.typ) // default type of untyped nil is untyped nil
} else if isInteger(x.typ) && isString(T) {
final = x.typ
}

2
src/go/types/expr.go
View File

@ -579,6 +579,8 @@ func (check *Checker) implicitType(x *operand, target Type) Type {
if !hasNil(target) {
return nil
}
// Preserve the type of nil as UntypedNil: see #13061.
return Typ[UntypedNil]
default:
return nil
}