bjoernager/rust
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Add a pointee_metadata_ty_or_projection helper

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This commit is contained in:
Scott McMurray 2024-06-22 12:11:14 -07:00
parent 9140c9ad5b
commit a76e1d9b09
8 changed files with 102 additions and 67 deletions
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14
compiler/rustc_middle/src/mir/tcx.rs
View file

@ -289,19 +289,7 @@ impl<'tcx> UnOp {
pub fn ty(&self, tcx: TyCtxt<'tcx>, arg_ty: Ty<'tcx>) -> Ty<'tcx> {
match self {
UnOp::Not | UnOp::Neg => arg_ty,
UnOp::PtrMetadata => {
let pointee_ty = arg_ty
.builtin_deref(true)
.unwrap_or_else(|| bug!("PtrMetadata of non-dereferenceable ty {arg_ty:?}"));
if pointee_ty.is_trivially_sized(tcx) {
tcx.types.unit
} else {
let Some(metadata_def_id) = tcx.lang_items().metadata_type() else {
bug!("No metadata_type lang item while looking at {arg_ty:?}")
};
Ty::new_projection(tcx, metadata_def_id, [pointee_ty])
}
}
UnOp::PtrMetadata => arg_ty.pointee_metadata_ty_or_projection(tcx),
}
}
}

28
compiler/rustc_middle/src/ty/sty.rs
View file

@ -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