Rollup merge of #66594 - Aaron1011:fix/debug-print-cycle, r=matthewjasper
Fix cycle when debug-printing opaque types Fixes #61577 When printing an opaque type in non-verbose mode, we use the `tcx.predicates_of` query to retrieve the opaque type's bounds for pretty-printing. However, the pervasiveness of logging within librustc means that we may already be executing `tcx.predicates_of` for the opaque type we're trying to print, leading to a cycle error. This commit adds a new 'no queries' thread-local flag to the pretty printer. This flag is enabled during the computation of `predicates_of` for opaque types, and causes us to print the opaque type in 'verbose' mode (which does not require computing any additinal queries). This should only affect debug logging for highly nested log messages, not any user-visible output.
This commit is contained in:
Mazdak Farrokhzad
GitHub
commit
a3ff52ce92
2 changed files with 93 additions and 62 deletions
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@ -49,6 +49,24 @@ macro_rules! define_scoped_cx {
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thread_local! {
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static FORCE_IMPL_FILENAME_LINE: Cell<bool> = Cell::new(false);
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static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = Cell::new(false);
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static NO_QUERIES: Cell<bool> = Cell::new(false);
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}
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/// Avoids running any queries during any prints that occur
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/// during the closure. This may alter the apperance of some
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/// types (e.g. forcing verbose printing for opaque types).
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/// This method is used during some queries (e.g. `predicates_of`
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/// for opaque types), to ensure that any debug printing that
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/// occurs during the query computation does not end up recursively
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/// calling the same query.
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pub fn with_no_queries<F: FnOnce() -> R, R>(f: F) -> R {
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NO_QUERIES.with(|no_queries| {
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let old = no_queries.get();
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no_queries.set(true);
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let result = f();
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no_queries.set(old);
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result
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})
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}
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/// Force us to name impls with just the filename/line number. We
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@ -556,52 +574,61 @@ pub trait PrettyPrinter<'tcx>:
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}
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ty::Opaque(def_id, substs) => {
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// FIXME(eddyb) print this with `print_def_path`.
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if self.tcx().sess.verbose() {
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// We use verbose printing in 'NO_QUERIES' mode, to
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// avoid needing to call `predicates_of`. This should
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// only affect certain debug messages (e.g. messages printed
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// from `rustc::ty` during the computation of `tcx.predicates_of`),
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// and should have no effect on any compiler output.
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if self.tcx().sess.verbose() || NO_QUERIES.with(|q| q.get()) {
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p!(write("Opaque({:?}, {:?})", def_id, substs));
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return Ok(self);
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}
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let def_key = self.tcx().def_key(def_id);
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if let Some(name) = def_key.disambiguated_data.data.get_opt_name() {
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p!(write("{}", name));
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let mut substs = substs.iter();
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// FIXME(eddyb) print this with `print_def_path`.
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if let Some(first) = substs.next() {
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p!(write("::<"));
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p!(print(first));
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for subst in substs {
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p!(write(", "), print(subst));
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}
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p!(write(">"));
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}
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return Ok(self);
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}
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// Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
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// by looking up the projections associated with the def_id.
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let bounds = self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs);
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return Ok(with_no_queries(|| {
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let mut first = true;
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let mut is_sized = false;
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p!(write("impl"));
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for predicate in bounds.predicates {
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if let Some(trait_ref) = predicate.to_opt_poly_trait_ref() {
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// Don't print +Sized, but rather +?Sized if absent.
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if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() {
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is_sized = true;
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continue;
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let def_key = self.tcx().def_key(def_id);
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if let Some(name) = def_key.disambiguated_data.data.get_opt_name() {
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p!(write("{}", name));
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let mut substs = substs.iter();
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// FIXME(eddyb) print this with `print_def_path`.
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if let Some(first) = substs.next() {
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p!(write("::<"));
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p!(print(first));
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for subst in substs {
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p!(write(", "), print(subst));
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}
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p!(write(">"));
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}
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p!(
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write("{}", if first { " " } else { "+" }),
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print(trait_ref));
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first = false;
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return Ok(self);
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}
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}
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if !is_sized {
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p!(write("{}?Sized", if first { " " } else { "+" }));
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} else if first {
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p!(write(" Sized"));
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}
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// Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
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// by looking up the projections associated with the def_id.
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let bounds = self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs);
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let mut first = true;
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let mut is_sized = false;
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p!(write("impl"));
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for predicate in bounds.predicates {
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if let Some(trait_ref) = predicate.to_opt_poly_trait_ref() {
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// Don't print +Sized, but rather +?Sized if absent.
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if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() {
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is_sized = true;
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continue;
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}
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p!(
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write("{}", if first { " " } else { "+" }),
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print(trait_ref));
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first = false;
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}
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}
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if !is_sized {
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p!(write("{}?Sized", if first { " " } else { "+" }));
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} else if first {
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p!(write(" Sized"));
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}
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Ok(self)
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})?);
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}
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ty::Str => p!(write("str")),
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ty::Generator(did, substs, movability) => {
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@ -2056,20 +2056,22 @@ fn explicit_predicates_of(
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Node::ImplItem(item) => match item.kind {
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ImplItemKind::OpaqueTy(ref bounds) => {
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let substs = InternalSubsts::identity_for_item(tcx, def_id);
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let opaque_ty = tcx.mk_opaque(def_id, substs);
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ty::print::with_no_queries(|| {
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let substs = InternalSubsts::identity_for_item(tcx, def_id);
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let opaque_ty = tcx.mk_opaque(def_id, substs);
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// Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
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let bounds = AstConv::compute_bounds(
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&icx,
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opaque_ty,
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bounds,
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SizedByDefault::Yes,
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tcx.def_span(def_id),
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);
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// Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
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let bounds = AstConv::compute_bounds(
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&icx,
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opaque_ty,
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bounds,
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SizedByDefault::Yes,
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tcx.def_span(def_id),
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);
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predicates.extend(bounds.predicates(tcx, opaque_ty));
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&item.generics
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predicates.extend(bounds.predicates(tcx, opaque_ty));
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&item.generics
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})
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}
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_ => &item.generics,
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},
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@ -2102,19 +2104,21 @@ fn explicit_predicates_of(
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ref generics,
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origin: _,
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}) => {
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let substs = InternalSubsts::identity_for_item(tcx, def_id);
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let opaque_ty = tcx.mk_opaque(def_id, substs);
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let bounds_predicates = ty::print::with_no_queries(|| {
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let substs = InternalSubsts::identity_for_item(tcx, def_id);
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let opaque_ty = tcx.mk_opaque(def_id, substs);
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// Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
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let bounds = AstConv::compute_bounds(
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&icx,
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opaque_ty,
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bounds,
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SizedByDefault::Yes,
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tcx.def_span(def_id),
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);
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// Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
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let bounds = AstConv::compute_bounds(
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&icx,
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opaque_ty,
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bounds,
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SizedByDefault::Yes,
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tcx.def_span(def_id),
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);
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let bounds_predicates = bounds.predicates(tcx, opaque_ty);
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bounds.predicates(tcx, opaque_ty)
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});
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if impl_trait_fn.is_some() {
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// opaque types
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return ty::GenericPredicates {
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