Rollup merge of #114800 - RalfJung:transparent, r=cuviper

std: add some missing repr(transparent)

For some types we don't want to stably guarantee this, so hide the `repr` from rustdoc. This nice approach was suggested by `@thomcc.`

1 files changed, 4 insertions, 4 deletions

diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index b59ec12790d..4082b208c12 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -82,12 +82,12 @@ use crate::str;
 #[stable(feature = "core_c_str", since = "1.64.0")]
 #[rustc_has_incoherent_inherent_impls]
 #[lang = "CStr"]
-// FIXME:
 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
 // on `CStr` being layout-compatible with `[u8]`.
-// When attribute privacy is implemented, `CStr` should be annotated as `#[repr(transparent)]`.
-// Anyway, `CStr` representation and layout are considered implementation detail, are
-// not documented and must not be relied upon.
+// However, `CStr` layout is considered an implementation detail and must not be relied upon. We
+// want `repr(transparent)` but we don't want it to show up in rustdoc, so we hide it under
+// `cfg(doc)`. This is an ad-hoc implementation of attribute privacy.
+#[cfg_attr(not(doc), repr(transparent))]
 pub struct CStr {
     // FIXME: this should not be represented with a DST slice but rather with
     //        just a raw `c_char` along with some form of marker to make