bjoernager/rust
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Update the interpreter to handle the new cases

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This commit is contained in:
Ben Kimock 2024-06-03 20:13:31 -04:00
parent f4b060e452
commit b710404f3b
1 changed files with 23 additions and 10 deletions
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33
compiler/rustc_const_eval/src/interpret/terminator.rs
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@ -294,17 +294,30 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
/// Unwrap types that are guaranteed a null-pointer-optimization
fn unfold_npo(&self, layout: TyAndLayout<'tcx>) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
// Check if this is `Option` wrapping some type.
let inner = match layout.ty.kind() {
ty::Adt(def, args) if self.tcx.is_diagnostic_item(sym::Option, def.did()) => {
args[0].as_type().unwrap()
}
_ => {
// Not an `Option`.
return Ok(layout);
}
// Check if this is `Option` wrapping some type or if this is `Result` wrapping a 1-ZST and
// another type.
let ty::Adt(def, args) = layout.ty.kind() else {
// Not an ADT, so definitely no NPO.
return Ok(layout);
};
let inner = self.layout_of(inner)?;
let inner = if self.tcx.is_diagnostic_item(sym::Option, def.did()) {
// The wrapped type is the only arg.
self.layout_of(args[0].as_type().unwrap())?
} else if self.tcx.is_diagnostic_item(sym::Result, def.did()) {
// We want to extract which (if any) of the args is not a 1-ZST.
let lhs = self.layout_of(args[0].as_type().unwrap())?;
let rhs = self.layout_of(args[1].as_type().unwrap())?;
if lhs.is_1zst() {
rhs
} else if rhs.is_1zst() {
lhs
} else {
return Ok(layout); // no NPO
}
} else {
return Ok(layout); // no NPO
};
// Check if the inner type is one of the NPO-guaranteed ones.
// For that we first unpeel transparent *structs* (but not unions).
let is_npo = |def: AdtDef<'tcx>| {