diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/syntax.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/syntax.rs | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index 99e59c770d7..6b4489026d3 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -320,8 +320,10 @@ pub enum StatementKind<'tcx> { /// <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/> for /// more details. /// - /// For code that is not specific to stacked borrows, you should consider retags to read - /// and modify the place in an opaque way. + /// For code that is not specific to stacked borrows, you should consider retags to read and + /// modify the place in an opaque way. + /// + /// Only `RetagKind::Default` and `RetagKind::FnEntry` are permitted. Retag(RetagKind, Box<Place<'tcx>>), /// Encodes a user's type ascription. These need to be preserved @@ -562,14 +564,13 @@ pub enum TerminatorKind<'tcx> { Unreachable, /// The behavior of this statement differs significantly before and after drop elaboration. - /// After drop elaboration, `Drop` executes the drop glue for the specified place, after which - /// it continues execution/unwinds at the given basic blocks. It is possible that executing drop - /// glue is special - this would be part of Rust's memory model. (**FIXME**: due we have an - /// issue tracking if drop glue has any interesting semantics in addition to those of a function - /// call?) - /// - /// `Drop` before drop elaboration is a *conditional* execution of the drop glue. Specifically, the - /// `Drop` will be executed if... + /// + /// After drop elaboration: `Drop` terminators are a complete nop for types that have no drop + /// glue. For other types, `Drop` terminators behave exactly like a call to + /// `core::mem::drop_in_place` with a pointer to the given place. + /// + /// `Drop` before drop elaboration is a *conditional* execution of the drop glue. Specifically, + /// the `Drop` will be executed if... /// /// **Needs clarification**: End of that sentence. This in effect should document the exact /// behavior of drop elaboration. The following sounds vaguely right, but I'm not quite sure: |