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Point out source of recursion

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This commit is contained in:
Michael Goulet
2023-11-08 07:19:01 +00:00
parent 82a2215481
commit 199af7cef0
13 changed files with 139 additions and 41 deletions
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58
compiler/rustc_middle/src/values.rs
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@@ -138,7 +138,8 @@ impl<'tcx, T> Value<TyCtxt<'tcx>> for Result<T, &'_ ty::layout::LayoutError<'_>>
let guar = if cycle_error.cycle[0].query.dep_kind == dep_kinds::layout_of
&& let Some(def_id) = cycle_error.cycle[0].query.ty_def_id
&& let Some(def_id) = def_id.as_local()
&& matches!(tcx.def_kind(def_id), DefKind::Closure)
&& let def_kind = tcx.def_kind(def_id)
&& matches!(def_kind, DefKind::Closure)
&& let Some(coroutine_kind) = tcx.coroutine_kind(def_id)
{
// FIXME: `def_span` for an fn-like coroutine will point to the fn's body
@@ -150,13 +151,56 @@ impl<'tcx, T> Value<TyCtxt<'tcx>> for Result<T, &'_ ty::layout::LayoutError<'_>>
} else {
tcx.def_span(def_id)
};
struct_span_err!(tcx.sess.dcx(), span, E0733, "recursion in an `async fn` requires boxing")
.span_label(span, "recursive `async fn`")
.note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`")
.note(
let mut diag = struct_span_err!(
tcx.sess.dcx(),
span,
E0733,
"recursion in {} {} requires boxing",
tcx.def_kind_descr_article(def_kind, def_id.to_def_id()),
tcx.def_kind_descr(def_kind, def_id.to_def_id()),
);
for (i, frame) in cycle_error.cycle.iter().enumerate() {
if frame.query.dep_kind != dep_kinds::layout_of {
continue;
}
let Some(frame_def_id) = frame.query.ty_def_id else {
continue;
};
let Some(frame_coroutine_kind) = tcx.coroutine_kind(frame_def_id) else {
continue;
};
let frame_span = frame
.query
.default_span(cycle_error.cycle[(i + 1) % cycle_error.cycle.len()].span);
if frame_span.is_dummy() {
continue;
}
if i == 0 {
diag.span_label(frame_span, "recursive call here");
} else {
let coroutine_span = if frame_coroutine_kind.is_fn_like() {
tcx.def_span(tcx.parent(frame_def_id))
} else {
tcx.def_span(frame_def_id)
};
let mut multispan = MultiSpan::from_span(coroutine_span);
multispan.push_span_label(frame_span, "...leading to this recursive call");
diag.span_note(
multispan,
format!("which leads to this {}", tcx.def_descr(frame_def_id)),
);
}
}
if matches!(
coroutine_kind,
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)
) {
diag.note("a recursive `async fn` call must introduce indirection such as `Box::pin` to avoid an infinitely sized future");
diag.note(
"consider using the `async_recursion` crate: https://crates.io/crates/async_recursion",
)
.emit()
);
}
diag.emit()
} else {
report_cycle(tcx.sess, cycle_error).emit()
};