bjoernager/rust
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also query type_uninhabited_from

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This commit is contained in:
Ralf Jung 2022-09-27 15:59:10 +02:00
parent c19daa472b
commit 67fd09d3b8
5 changed files with 49 additions and 40 deletions
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14
compiler/rustc_lint/src/builtin.rs
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@ -2425,8 +2425,12 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
}
/// Determines whether the given type is inhabited. `None` means that we don't know.
fn ty_inhabited(ty: Ty<'_>) -> Option<bool> {
fn ty_inhabited<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<bool> {
use rustc_type_ir::sty::TyKind::*;
if !cx.tcx.type_uninhabited_from(cx.param_env.and(ty)).is_empty() {
// This is definitely uninhabited from some module.
return Some(false);
}
match ty.kind() {
Never => Some(false),
Int(_) | Uint(_) | Float(_) | Bool | Char | RawPtr(_) => Some(true),
@ -2436,10 +2440,13 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
}
}
/// Determines whether a product type formed from a list of types is inhabited.
fn tys_inhabited<'tcx>(tys: impl Iterator<Item = Ty<'tcx>>) -> Option<bool> {
fn tys_inhabited<'tcx>(
cx: &LateContext<'tcx>,
tys: impl Iterator<Item = Ty<'tcx>>,
) -> Option<bool> {
let mut definitely_inhabited = true; // with no fields, we are definitely inhabited.
for ty in tys {
match ty_inhabited(ty) {
match ty_inhabited(cx, ty) {
// If any type is uninhabited, the product is uninhabited.
Some(false) => return Some(false),
// Otherwise go searching for a `None`.
@ -2550,6 +2557,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
let span = cx.tcx.def_span(adt_def.did());
let mut potential_variants = adt_def.variants().iter().filter_map(|variant| {
let inhabited = tys_inhabited(
cx,
variant.fields.iter().map(|field| field.ty(cx.tcx, substs)),
);
let definitely_inhabited = match inhabited {