From 822f787546f93e0319def3576ff7550e46fb3c1e Mon Sep 17 00:00:00 2001 From: Mazdak Farrokhzad Date: Thu, 24 Oct 2019 02:24:14 +0200 Subject: Adjust the tracking issue for `untagged_unions`. Also elaborate on some feature gates in `active.rs`. --- src/libsyntax/feature_gate/active.rs | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'src/libsyntax') diff --git a/src/libsyntax/feature_gate/active.rs b/src/libsyntax/feature_gate/active.rs index 1386eac48da..4f92401d2bc 100644 --- a/src/libsyntax/feature_gate/active.rs +++ b/src/libsyntax/feature_gate/active.rs @@ -330,8 +330,13 @@ declare_features! ( /// Allows exhaustive pattern matching on types that contain uninhabited types. (active, exhaustive_patterns, "1.13.0", Some(51085), None), - /// Allows untagged unions `union U { ... }`. - (active, untagged_unions, "1.13.0", Some(32836), None), + /// Allows `union`s to implement `Drop`. Moreover, `union`s may now include fields + /// that don't implement `Copy` as long as they don't have any drop glue. + /// This is checked recursively. On encountering type variable where no progress can be made, + /// `T: Copy` is used as a substitute for "no drop glue". + /// + /// NOTE: A limited form of `union U { ... }` was accepted in 1.19.0. + (active, untagged_unions, "1.13.0", Some(55149), None), /// Allows `#[link(..., cfg(..))]`. (active, link_cfg, "1.14.0", Some(37406), None), @@ -522,13 +527,16 @@ declare_features! ( /// Allows the definition of `const extern fn` and `const unsafe extern fn`. (active, const_extern_fn, "1.40.0", Some(64926), None), - // Allows the use of raw-dylibs (RFC 2627). + /// Allows the use of raw-dylibs (RFC 2627). (active, raw_dylib, "1.40.0", Some(58713), None), - /// Enable accurate caller location reporting during panic (RFC 2091). + /// Allows `#[track_caller]` to be used which provides + /// accurate caller location reporting during panic (RFC 2091). (active, track_caller, "1.40.0", Some(47809), None), - /// Non-object safe trait objects safe to use but cannot be created in safe rust + /// Allows making `dyn Trait` well-formed even if `Trait` is not object safe. + /// In that case, `dyn Trait: Trait` does not hold. Moreover, coercions and + /// casts in safe Rust to `dyn Trait` for such a `Trait` is also forbidden. (active, object_safe_for_dispatch, "1.40.0", Some(43561), None), // ------------------------------------------------------------------------- -- cgit 1.4.1-3-g733a5