bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Clean up infer_return_ty_for_fn_sig

Browse source
This commit is contained in:
Michael Goulet 2024-12-13 15:10:58 +00:00
parent 4847d6a9d0
commit d82c520f14
1 changed files with 95 additions and 86 deletions
Download patch file Download diff file Expand all files Collapse all files

181
compiler/rustc_hir_analysis/src/collect.rs
View file

@ -1330,7 +1330,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
.. ..
}) })
| Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => { | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
infer_return_ty_for_fn_sig(sig, generics, def_id, &icx) lower_fn_sig_recovering_infer_ret_ty(&icx, sig, generics, def_id)
} }
ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => { ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
@ -1347,7 +1347,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
None, None,
) )
} else { } else {
infer_return_ty_for_fn_sig(sig, generics, def_id, &icx) lower_fn_sig_recovering_infer_ret_ty(&icx, sig, generics, def_id)
} }
} }
@ -1397,99 +1397,108 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
ty::EarlyBinder::bind(output) ty::EarlyBinder::bind(output)
} }
fn infer_return_ty_for_fn_sig<'tcx>( fn lower_fn_sig_recovering_infer_ret_ty<'tcx>(
sig: &hir::FnSig<'tcx>,
generics: &hir::Generics<'_>,
def_id: LocalDefId,
icx: &ItemCtxt<'tcx>, icx: &ItemCtxt<'tcx>,
sig: &'tcx hir::FnSig<'tcx>,
generics: &'tcx hir::Generics<'tcx>,
def_id: LocalDefId,
) -> ty::PolyFnSig<'tcx> {
if let Some(infer_ret_ty) = sig.decl.output.get_infer_ret_ty() {
return recover_infer_ret_ty(icx, infer_ret_ty, generics, def_id);
}
icx.lowerer().lower_fn_ty(
icx.tcx().local_def_id_to_hir_id(def_id),
sig.header.safety,
sig.header.abi,
sig.decl,
Some(generics),
None,
)
}
fn recover_infer_ret_ty<'tcx>(
icx: &ItemCtxt<'tcx>,
infer_ret_ty: &'tcx hir::Ty<'tcx>,
generics: &'tcx hir::Generics<'tcx>,
def_id: LocalDefId,
) -> ty::PolyFnSig<'tcx> { ) -> ty::PolyFnSig<'tcx> {
let tcx = icx.tcx; let tcx = icx.tcx;
let hir_id = tcx.local_def_id_to_hir_id(def_id); let hir_id = tcx.local_def_id_to_hir_id(def_id);
match sig.decl.output.get_infer_ret_ty() { let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
Some(ty) => {
let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
// Typeck doesn't expect erased regions to be returned from `type_of`.
// This is a heuristic approach. If the scope has region parameters,
// we should change fn_sig's lifetime from `ReErased` to `ReError`,
// otherwise to `ReStatic`.
let has_region_params = generics.params.iter().any(|param| match param.kind {
GenericParamKind::Lifetime { .. } => true,
_ => false,
});
let fn_sig = fold_regions(tcx, fn_sig, |r, _| match *r {
ty::ReErased => {
if has_region_params {
ty::Region::new_error_with_message(
tcx,
DUMMY_SP,
"erased region is not allowed here in return type",
)
} else {
tcx.lifetimes.re_static
}
}
_ => r,
});
let mut visitor = HirPlaceholderCollector::default(); // Typeck doesn't expect erased regions to be returned from `type_of`.
visitor.visit_ty(ty); // This is a heuristic approach. If the scope has region parameters,
// we should change fn_sig's lifetime from `ReErased` to `ReError`,
let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type"); // otherwise to `ReStatic`.
let ret_ty = fn_sig.output(); let has_region_params = generics.params.iter().any(|param| match param.kind {
// Don't leak types into signatures unless they're nameable! GenericParamKind::Lifetime { .. } => true,
// For example, if a function returns itself, we don't want that _ => false,
// recursive function definition to leak out into the fn sig. });
let mut recovered_ret_ty = None; let fn_sig = fold_regions(tcx, fn_sig, |r, _| match *r {
ty::ReErased => {
if let Some(suggestable_ret_ty) = ret_ty.make_suggestable(tcx, false, None) { if has_region_params {
diag.span_suggestion( ty::Region::new_error_with_message(
ty.span, tcx,
"replace with the correct return type", DUMMY_SP,
suggestable_ret_ty, "erased region is not allowed here in return type",
Applicability::MachineApplicable, )
); } else {
recovered_ret_ty = Some(suggestable_ret_ty); tcx.lifetimes.re_static
} else if let Some(sugg) = suggest_impl_trait(
&tcx.infer_ctxt().build(TypingMode::non_body_analysis()),
tcx.param_env(def_id),
ret_ty,
) {
diag.span_suggestion(
ty.span,
"replace with an appropriate return type",
sugg,
Applicability::MachineApplicable,
);
} else if ret_ty.is_closure() {
diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
} }
// Also note how `Fn` traits work just in case!
if ret_ty.is_closure() {
diag.note(
"for more information on `Fn` traits and closure types, see \
https://doc.rust-lang.org/book/ch13-01-closures.html",
);
}
let guar = diag.emit();
ty::Binder::dummy(tcx.mk_fn_sig(
fn_sig.inputs().iter().copied(),
recovered_ret_ty.unwrap_or_else(|| Ty::new_error(tcx, guar)),
fn_sig.c_variadic,
fn_sig.safety,
fn_sig.abi,
))
} }
None => icx.lowerer().lower_fn_ty( _ => r,
hir_id, });
sig.header.safety,
sig.header.abi, let mut visitor = HirPlaceholderCollector::default();
sig.decl, visitor.visit_ty(infer_ret_ty);
Some(generics),
None, let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type");
), let ret_ty = fn_sig.output();
// Don't leak types into signatures unless they're nameable!
// For example, if a function returns itself, we don't want that
// recursive function definition to leak out into the fn sig.
let mut recovered_ret_ty = None;
if let Some(suggestable_ret_ty) = ret_ty.make_suggestable(tcx, false, None) {
diag.span_suggestion(
infer_ret_ty.span,
"replace with the correct return type",
suggestable_ret_ty,
Applicability::MachineApplicable,
);
recovered_ret_ty = Some(suggestable_ret_ty);
} else if let Some(sugg) = suggest_impl_trait(
&tcx.infer_ctxt().build(TypingMode::non_body_analysis()),
tcx.param_env(def_id),
ret_ty,
) {
diag.span_suggestion(
infer_ret_ty.span,
"replace with an appropriate return type",
sugg,
Applicability::MachineApplicable,
);
} else if ret_ty.is_closure() {
diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
} }
// Also note how `Fn` traits work just in case!
if ret_ty.is_closure() {
diag.note(
"for more information on `Fn` traits and closure types, see \
https://doc.rust-lang.org/book/ch13-01-closures.html",
);
}
let guar = diag.emit();
ty::Binder::dummy(tcx.mk_fn_sig(
fn_sig.inputs().iter().copied(),
recovered_ret_ty.unwrap_or_else(|| Ty::new_error(tcx, guar)),
fn_sig.c_variadic,
fn_sig.safety,
fn_sig.abi,
))
} }
pub fn suggest_impl_trait<'tcx>( pub fn suggest_impl_trait<'tcx>(