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go/types: better position for "3-index slice of string" error

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This is a port of CL 363670 from types2 to go/types.

Change-Id: I2ac3a5f86bb4eafddd2854e193083b2b737e29b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/364901
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Robert Findley 2021-11-17 19:37:04 -05:00
parent 3404ee3e86
commit 72f0976ac4
3 changed files with 9 additions and 5 deletions
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6
src/go/types/index.go
View file

@ -223,7 +223,11 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
case *Basic:
if isString(u) {
if e.Slice3 {
check.invalidOp(x, _InvalidSliceExpr, "3-index slice of string")
at := e.Max
if at == nil {
at = e // e.Index[2] should be present but be careful
}
check.invalidOp(at, _InvalidSliceExpr, "3-index slice of string")
x.mode = invalid
return
}

4
src/go/types/testdata/check/expr3.src vendored
View file

@ -109,8 +109,8 @@ func indexes() {
_ = t[- /* ERROR "negative" */ 1]
_ = t[- /* ERROR "negative" */ 1 :]
_ = t[: - /* ERROR "negative" */ 1]
_ = t /* ERROR "3-index slice of string" */ [1:2:3]
_ = "foo" /* ERROR "3-index slice of string" */ [1:2:3]
_ = t[1:2:3 /* ERROR "3-index slice of string" */ ]
_ = "foo"[1:2:3 /* ERROR "3-index slice of string" */ ]
var t0 byte
t0 = t[0]
_ = t0

4
src/go/types/testdata/check/typeparams.go2 vendored
View file

@ -129,7 +129,7 @@ func _[T interface{ ~[10]E }, E any] (x T, i, j, k int) { var _ []E = x[i:j:k] }
func _[T interface{ ~[]byte }] (x T, i, j, k int) { var _ T = x[i:j] }
func _[T interface{ ~[]byte }] (x T, i, j, k int) { var _ T = x[i:j:k] }
func _[T interface{ ~string }] (x T, i, j, k int) { var _ T = x[i:j] }
func _[T interface{ ~string }] (x T, i, j, k int) { var _ T = x /* ERROR 3-index slice of string */ [i:j:k] }
func _[T interface{ ~string }] (x T, i, j, k int) { var _ T = x[i:j:k /* ERROR 3-index slice of string */ ] }
type myByte1 []byte
type myByte2 []byte
@ -137,7 +137,7 @@ func _[T interface{ []byte | myByte1 | myByte2 }] (x T, i, j, k int) { var _ T =
func _[T interface{ []byte | myByte1 | []int }] (x T, i, j, k int) { var _ T = x /* ERROR no structural type */ [i:j:k] }
func _[T interface{ []byte | myByte1 | myByte2 | string }] (x T, i, j, k int) { var _ T = x[i:j] }
func _[T interface{ []byte | myByte1 | myByte2 | string }] (x T, i, j, k int) { var _ T = x /* ERROR 3-index slice of string */ [i:j:k] }
func _[T interface{ []byte | myByte1 | myByte2 | string }] (x T, i, j, k int) { var _ T = x[i:j:k /* ERROR 3-index slice of string */ ] }
func _[T interface{ []byte | myByte1 | []int | string }] (x T, i, j, k int) { var _ T = x /* ERROR no structural type */ [i:j] }
// len/cap built-ins