diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/sty.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/sty.rs | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index 9c8a3484aa5..709c5fe2305 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -1638,6 +1638,34 @@ impl<'tcx> Ty<'tcx> { } } + /// Given a pointer or reference type, returns the type of the *pointee*'s + /// metadata. If it can't be determined exactly (perhaps due to still + /// being generic) then a projection through `ptr::Pointee` will be returned. + /// + /// This is particularly useful for getting the type of the result of + /// [`UnOp::PtrMetadata`](crate::mir::UnOp::PtrMetadata). + /// + /// Panics if `self` is not dereferencable. + #[track_caller] + pub fn pointee_metadata_ty_or_projection(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + let Some(pointee_ty) = self.builtin_deref(true) else { + bug!("Type {self:?} is not a pointer or reference type") + }; + if pointee_ty.is_trivially_sized(tcx) { + tcx.types.unit + } else { + match pointee_ty.ptr_metadata_ty_or_tail(tcx, |x| x) { + Ok(metadata_ty) => metadata_ty, + Err(tail_ty) => { + let Some(metadata_def_id) = tcx.lang_items().metadata_type() else { + bug!("No metadata_type lang item while looking at {self:?}") + }; + Ty::new_projection(tcx, metadata_def_id, [tail_ty]) + } + } + } + } + /// When we create a closure, we record its kind (i.e., what trait /// it implements, constrained by how it uses its borrows) into its /// [`ty::ClosureArgs`] or [`ty::CoroutineClosureArgs`] using a type |