From: Robert Griesemer Date: Tue, 5 Oct 2021 17:29:21 +0000 (-0700) Subject: cmd/compile/internal/types2: implement generic slice expressions X-Git-Tag: go1.18beta1~1049 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7e69c5decf0b95ce2856769b9798c3a1cf3078ee;p=gostls13.git cmd/compile/internal/types2: implement generic slice expressions For now, the constraint's underlying type set must be a single type that is sliceable. Change-Id: I08b6a2e88fe35e8238a95b3f40dc969689021a0f Reviewed-on: https://go-review.googlesource.com/c/go/+/354070 Trust: Robert Griesemer Run-TryBot: Robert Griesemer TryBot-Result: Go Bot Reviewed-by: Ian Lance Taylor --- diff --git a/src/cmd/compile/internal/types2/index.go b/src/cmd/compile/internal/types2/index.go index 848a70dea8..47a5e50f62 100644 --- a/src/cmd/compile/internal/types2/index.go +++ b/src/cmd/compile/internal/types2/index.go @@ -207,7 +207,7 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) { valid := false length := int64(-1) // valid if >= 0 - switch typ := under(x.typ).(type) { + switch typ := optype(x.typ).(type) { case *Basic: if isString(typ) { if e.Full { @@ -246,11 +246,6 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) { case *Slice: valid = true // x.typ doesn't change - - case *TypeParam: - check.error(x, "generic slice expressions not yet implemented") - x.mode = invalid - return } if !valid { diff --git a/src/cmd/compile/internal/types2/testdata/check/typeparams.go2 b/src/cmd/compile/internal/types2/testdata/check/typeparams.go2 index 69b6925b9f..29c25b0bb4 100644 --- a/src/cmd/compile/internal/types2/testdata/check/typeparams.go2 +++ b/src/cmd/compile/internal/types2/testdata/check/typeparams.go2 @@ -115,9 +115,13 @@ func _[T interface{ [10]byte | string }](x T, i int) { _ = x[i]; _ = x[9]; _ = x func _[T interface{ [10]int | *[20]int | []int }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] } // slicing -// TODO(gri) implement this -func _[T interface{ ~string }] (x T, i, j, k int) { _ = x /* ERROR generic slice expressions not yet implemented */ [i:j:k] } +func _[T interface{ ~[10]E }, E any] (x T, i, j, k int) { var _ []E = x[i:j] } +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] } // len/cap built-ins