From 146e8d4994052ee4a58bec7e2cf37e568ce1e4e5 Mon Sep 17 00:00:00 2001 From: Nevkontakte Date: Mon, 13 Sep 2021 22:40:30 +0000 Subject: [PATCH] reflect: use Value.Len instead of conversion to slice header This change is functionally equivalent, but reduces reliance on unsafe features. This would allow GopherJS to avoid an additional patch to the standard library we'd have to maintain in order to remain compatible with Go 1.17+. Change-Id: I4f113db0c572ec0b81ebfecf5a137145f6c8c41d GitHub-Last-Rev: 94ebb393bac93579b6455555822691c0d69e2d42 GitHub-Pull-Request: golang/go#48346 Reviewed-on: https://go-review.googlesource.com/c/go/+/349469 Reviewed-by: Keith Randall Reviewed-by: Ian Lance Taylor Trust: Keith Randall Run-TryBot: Keith Randall TryBot-Result: Go Bot --- src/reflect/value.go | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/src/reflect/value.go b/src/reflect/value.go index bc48a76ce6..33b81d7209 100644 --- a/src/reflect/value.go +++ b/src/reflect/value.go @@ -2940,8 +2940,7 @@ func (v Value) CanConvert(t Type) bool { // from slice to pointer-to-array. if vt.Kind() == Slice && t.Kind() == Ptr && t.Elem().Kind() == Array { n := t.Elem().Len() - h := (*unsafeheader.Slice)(v.ptr) - if n > h.Len { + if n > v.Len() { return false } } @@ -3208,10 +3207,10 @@ func cvtStringRunes(v Value, t Type) Value { // convertOp: []T -> *[N]T func cvtSliceArrayPtr(v Value, t Type) Value { n := t.Elem().Len() - h := (*unsafeheader.Slice)(v.ptr) - if n > h.Len { - panic("reflect: cannot convert slice with length " + itoa.Itoa(h.Len) + " to pointer to array with length " + itoa.Itoa(n)) + if n > v.Len() { + panic("reflect: cannot convert slice with length " + itoa.Itoa(v.Len()) + " to pointer to array with length " + itoa.Itoa(n)) } + h := (*unsafeheader.Slice)(v.ptr) return Value{t.common(), h.Data, v.flag&^(flagIndir|flagAddr|flagKindMask) | flag(Ptr)} }