Rollup merge of #125750 - compiler-errors:expect, r=lcnr

Align `Term` methods with `GenericArg` methods, add `Term::expect_*`

* `Term::ty` -> `Term::as_type`.
* `Term::ct` -> `Term::as_const`.
* Adds `Term::expect_type` and `Term::expect_const`, and uses them in favor of `.ty().unwrap()`, etc.

I could also shorten these to `as_ty` and then do `GenericArg::as_ty` as well, but I do think the `as_` is important to signal that this is a conversion method, and not a getter, like `Const::ty` is.

r? types

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -263,7 +263,7 @@ fn push_debuginfo_type_name<'tcx>(
                         let ExistentialProjection { def_id: item_def_id, term, .. } =
                             tcx.instantiate_bound_regions_with_erased(bound);
                         // FIXME(associated_const_equality): allow for consts here
-                        (item_def_id, term.ty().unwrap())
+                        (item_def_id, term.expect_type())
                     })
                     .collect();
 

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -2281,7 +2281,7 @@ fn try_report_async_mismatch<'tcx>(
             && let Some(proj) = proj.no_bound_vars()
             && infcx.can_eq(
                 error.root_obligation.param_env,
-                proj.term.ty().unwrap(),
+                proj.term.expect_type(),
                 impl_sig.output(),
             )
         {

compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs

@@ -267,7 +267,7 @@ fn report_mismatched_rpitit_signature<'tcx>(
             .explicit_item_bounds(future_ty.def_id)
             .iter_instantiated_copied(tcx, future_ty.args)
             .find_map(|(clause, _)| match clause.kind().no_bound_vars()? {
-                ty::ClauseKind::Projection(proj) => proj.term.ty(),
+                ty::ClauseKind::Projection(proj) => proj.term.as_type(),
                 _ => None,
             })
         else {

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -441,7 +441,9 @@ fn fn_sig_suggestion<'tcx>(
         output = if let ty::Alias(_, alias_ty) = *output.kind() {
             tcx.explicit_item_super_predicates(alias_ty.def_id)
                 .iter_instantiated_copied(tcx, alias_ty.args)
-                .find_map(|(bound, _)| bound.as_projection_clause()?.no_bound_vars()?.term.ty())
+                .find_map(|(bound, _)| {
+                    bound.as_projection_clause()?.no_bound_vars()?.term.as_type()
+                })
                 .unwrap_or_else(|| {
                     span_bug!(
                         ident.span,

compiler/rustc_hir_typeck/src/closure.rs

@@ -485,7 +485,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         // Since this is a return parameter type it is safe to unwrap.
-        let ret_param_ty = projection.skip_binder().term.ty().unwrap();
+        let ret_param_ty = projection.skip_binder().term.expect_type();
         let ret_param_ty = self.resolve_vars_if_possible(ret_param_ty);
         debug!(?ret_param_ty);
 
@@ -956,7 +956,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let output_ty = self.resolve_vars_if_possible(predicate.term);
         debug!("deduce_future_output_from_projection: output_ty={:?}", output_ty);
         // This is a projection on a Fn trait so will always be a type.
-        Some(output_ty.ty().unwrap())
+        Some(output_ty.expect_type())
     }
 
     /// Converts the types that the user supplied, in case that doing

compiler/rustc_hir_typeck/src/typeck_root_ctxt.rs

@@ -160,7 +160,7 @@ impl<'tcx> TypeckRootCtxt<'tcx> {
         {
             // If the projection predicate (Foo::Bar == X) has X as a non-TyVid,
             // we need to make it into one.
-            if let Some(vid) = predicate.term.ty().and_then(|ty| ty.ty_vid()) {
+            if let Some(vid) = predicate.term.as_type().and_then(|ty| ty.ty_vid()) {
                 debug!("infer_var_info: {:?}.output = true", vid);
                 infer_var_info.entry(vid).or_default().output = true;
             }

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -425,7 +425,7 @@ impl<'tcx> InferCtxt<'tcx> {
                         ty::ClauseKind::Projection(projection_predicate)
                             if projection_predicate.projection_term.def_id == item_def_id =>
                         {
-                            projection_predicate.term.ty()
+                            projection_predicate.term.as_type()
                         }
                         _ => None,
                     })

compiler/rustc_infer/src/infer/mod.rs

@@ -424,8 +424,8 @@ pub enum ValuePairs<'tcx> {
 impl<'tcx> ValuePairs<'tcx> {
     pub fn ty(&self) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
         if let ValuePairs::Terms(ExpectedFound { expected, found }) = self
-            && let Some(expected) = expected.ty()
-            && let Some(found) = found.ty()
+            && let Some(expected) = expected.as_type()
+            && let Some(found) = found.as_type()
         {
             Some((expected, found))
         } else {

compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs

@@ -83,7 +83,7 @@ impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
                 };
                 // Only check types, since those are the only things that may
                 // have opaques in them anyways.
-                let Some(proj_term) = proj.term.ty() else { return };
+                let Some(proj_term) = proj.term.as_type() else { return };
 
                 // HACK: `impl Trait<Assoc = impl Trait2>` from an RPIT is "ok"...
                 if let ty::Alias(ty::Opaque, opaque_ty) = *proj_term.kind()

compiler/rustc_middle/src/ty/mod.rs

@@ -624,14 +624,22 @@ impl<'tcx> Term<'tcx> {
         }
     }
 
-    pub fn ty(&self) -> Option<Ty<'tcx>> {
+    pub fn as_type(&self) -> Option<Ty<'tcx>> {
         if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None }
     }
 
-    pub fn ct(&self) -> Option<Const<'tcx>> {
+    pub fn expect_type(&self) -> Ty<'tcx> {
+        self.as_type().expect("expected a type, but found a const")
+    }
+
+    pub fn as_const(&self) -> Option<Const<'tcx>> {
         if let TermKind::Const(c) = self.unpack() { Some(c) } else { None }
     }
 
+    pub fn expect_const(&self) -> Const<'tcx> {
+        self.as_const().expect("expected a const, but found a type")
+    }
+
     pub fn into_arg(self) -> GenericArg<'tcx> {
         match self.unpack() {
             TermKind::Ty(ty) => ty.into(),

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1077,7 +1077,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         }
 
                         p!(")");
-                        if let Some(ty) = return_ty.skip_binder().ty() {
+                        if let Some(ty) = return_ty.skip_binder().as_type() {
                             if !ty.is_unit() {
                                 p!(" -> ", print(return_ty));
                             }
@@ -1144,7 +1144,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     for (assoc_item_def_id, term) in assoc_items {
                         // Skip printing `<{coroutine@} as Coroutine<_>>::Return` from async blocks,
                         // unless we can find out what coroutine return type it comes from.
-                        let term = if let Some(ty) = term.skip_binder().ty()
+                        let term = if let Some(ty) = term.skip_binder().as_type()
                             && let ty::Alias(ty::Projection, proj) = ty.kind()
                             && let Some(assoc) = tcx.opt_associated_item(proj.def_id)
                             && assoc.trait_container(tcx) == tcx.lang_items().coroutine_trait()
@@ -1322,7 +1322,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                             p!(pretty_fn_sig(
                                 tys,
                                 false,
-                                proj.skip_binder().term.ty().expect("Return type was a const")
+                                proj.skip_binder().term.as_type().expect("Return type was a const")
                             ));
                             resugared = true;
                         }

compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs

@@ -726,7 +726,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReplaceProjectionWith<'_, 'tcx> {
                     )
                     .expect("expected to be able to unify goal projection with dyn's projection"),
             );
-            proj.term.ty().unwrap()
+            proj.term.expect_type()
         } else {
             ty.super_fold_with(self)
         }

compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs

@@ -17,7 +17,7 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     ) -> QueryResult<'tcx> {
         let tcx = self.interner();
         let opaque_ty = goal.predicate.alias;
-        let expected = goal.predicate.term.ty().expect("no such thing as an opaque const");
+        let expected = goal.predicate.term.as_type().expect("no such thing as an opaque const");
 
         match (goal.param_env.reveal(), self.solver_mode()) {
             (Reveal::UserFacing, SolverMode::Normal) => {

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -553,7 +553,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
     }
 
     fn is_self_referential_projection(&self, p: ty::PolyProjectionPredicate<'tcx>) -> bool {
-        if let Some(ty) = p.term().skip_binder().ty() {
+        if let Some(ty) = p.term().skip_binder().as_type() {
             matches!(ty.kind(), ty::Alias(ty::Projection, proj) if proj == &p.skip_binder().projection_term.expect_ty(self.tcx))
         } else {
             false

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1112,7 +1112,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                 {
                                     Some((
                                         DefIdOrName::DefId(def_id),
-                                        pred.kind().rebind(proj.term.ty().unwrap()),
+                                        pred.kind().rebind(proj.term.expect_type()),
                                         pred.kind().rebind(args.as_slice()),
                                     ))
                                 } else {
@@ -1129,7 +1129,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             {
                                 Some((
                                     DefIdOrName::Name("trait object"),
-                                    pred.rebind(proj.term.ty().unwrap()),
+                                    pred.rebind(proj.term.expect_type()),
                                     pred.rebind(args.as_slice()),
                                 ))
                             } else {
@@ -1157,7 +1157,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             {
                                 Some((
                                     name,
-                                    pred.kind().rebind(proj.term.ty().unwrap()),
+                                    pred.kind().rebind(proj.term.expect_type()),
                                     pred.kind().rebind(args.as_slice()),
                                 ))
                             } else {
@@ -3840,7 +3840,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     })
                 } else if let Some(where_pred) = where_pred.as_projection_clause()
                     && let Some(failed_pred) = failed_pred.as_projection_clause()
-                    && let Some(found) = failed_pred.skip_binder().term.ty()
+                    && let Some(found) = failed_pred.skip_binder().term.as_type()
                 {
                     type_diffs = vec![Sorts(ty::error::ExpectedFound {
                         expected: where_pred

compiler/rustc_trait_selection/src/traits/normalize.rs

@@ -259,7 +259,7 @@ impl<'a, 'b, 'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTypeNormalizer<'a, 'b, 'tcx
                     obligations.len = ?self.obligations.len(),
                     "AssocTypeNormalizer: normalized type"
                 );
-                normalized_ty.ty().unwrap()
+                normalized_ty.expect_type()
             }
 
             ty::Projection => {
@@ -289,7 +289,7 @@ impl<'a, 'b, 'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTypeNormalizer<'a, 'b, 'tcx
                 )
                 .ok()
                 .flatten()
-                .map(|term| term.ty().unwrap())
+                .map(|term| term.expect_type())
                 .map(|normalized_ty| {
                     PlaceholderReplacer::replace_placeholders(
                         infcx,

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -946,7 +946,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // since we don't actually use them.
                 &mut vec![],
             )
-            .ty()
+            .as_type()
             .unwrap();
 
             if let ty::Dynamic(data, ..) = ty.kind() { data.principal() } else { None }

compiler/rustc_trait_selection/src/traits/wf.rs

@@ -286,7 +286,7 @@ fn extend_cause_with_original_assoc_item_obligation<'tcx>(
             // implemented, but rather from a "second order" obligation, where an associated
             // type has a projection coming from another associated type.
             // See `tests/ui/traits/assoc-type-in-superbad.rs` for an example.
-            if let Some(term_ty) = proj.term.ty()
+            if let Some(term_ty) = proj.term.as_type()
                 && let Some(impl_item_span) = ty_to_impl_span(term_ty)
             {
                 cause.span = impl_item_span;

compiler/rustc_traits/src/normalize_projection_ty.rs

@@ -58,7 +58,7 @@ fn normalize_canonicalized_projection_ty<'tcx>(
             // FIXME(associated_const_equality): All users of normalize_canonicalized_projection_ty
             // expected a type, but there is the possibility it could've been a const now.
             // Maybe change it to a Term later?
-            Ok(NormalizationResult { normalized_ty: answer.ty().unwrap() })
+            Ok(NormalizationResult { normalized_ty: answer.expect_type() })
         },
     )
 }

src/tools/clippy/clippy_lints/src/methods/iter_on_single_or_empty_collections.rs

@@ -42,7 +42,7 @@ fn is_arg_ty_unified_in_fn<'tcx>(
     cx.tcx.predicates_of(fn_id).predicates.iter().any(|(clause, _)| {
         clause
             .as_projection_clause()
-            .and_then(|p| p.map_bound(|p| p.term.ty()).transpose())
+            .and_then(|p| p.map_bound(|p| p.term.as_type()).transpose())
             .is_some_and(|ty| ty.skip_binder() == arg_ty_in_args)
     }) || fn_sig
         .inputs()

src/tools/clippy/clippy_lints/src/needless_borrows_for_generic_args.rs

@@ -311,7 +311,7 @@ fn is_mixed_projection_predicate<'tcx>(
 ) -> bool {
     let generics = cx.tcx.generics_of(callee_def_id);
     // The predicate requires the projected type to equal a type parameter from the parent context.
-    if let Some(term_ty) = projection_predicate.term.ty()
+    if let Some(term_ty) = projection_predicate.term.as_type()
         && let ty::Param(term_param_ty) = term_ty.kind()
         && (term_param_ty.index as usize) < generics.parent_count
     {
@@ -370,7 +370,7 @@ fn replace_types<'tcx>(
         if replaced.insert(param_ty.index) {
             for projection_predicate in projection_predicates {
                 if projection_predicate.projection_term.self_ty() == param_ty.to_ty(cx.tcx)
-                    && let Some(term_ty) = projection_predicate.term.ty()
+                    && let Some(term_ty) = projection_predicate.term.as_type()
                     && let ty::Param(term_param_ty) = term_ty.kind()
                 {
                     let projection = projection_predicate

src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs

@@ -100,12 +100,12 @@ fn get_args_to_check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Ve
                     {
                         if ord_preds
                             .iter()
-                            .any(|ord| Some(ord.self_ty()) == return_ty_pred.term.ty())
+                            .any(|ord| Some(ord.self_ty()) == return_ty_pred.term.as_type())
                         {
                             args_to_check.push((i, "Ord".to_string()));
                         } else if partial_ord_preds
                             .iter()
-                            .any(|pord| pord.self_ty() == return_ty_pred.term.ty().unwrap())
+                            .any(|pord| pord.self_ty() == return_ty_pred.term.expect_type())
                         {
                             args_to_check.push((i, "PartialOrd".to_string()));
                         }

src/tools/clippy/clippy_utils/src/ty.rs

@@ -750,7 +750,7 @@ pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'t
                     let output = bounds
                         .projection_bounds()
                         .find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
-                        .map(|p| p.map_bound(|p| p.term.ty().unwrap()));
+                        .map(|p| p.map_bound(|p| p.term.expect_type()));
                     Some(ExprFnSig::Trait(bound.map_bound(|b| b.args.type_at(0)), output, None))
                 },
                 _ => None,
@@ -798,7 +798,7 @@ fn sig_from_bounds<'tcx>(
                     // Multiple different fn trait impls. Is this even allowed?
                     return None;
                 }
-                output = Some(pred.kind().rebind(p.term.ty().unwrap()));
+                output = Some(pred.kind().rebind(p.term.expect_type()));
             },
             _ => (),
         }
@@ -836,7 +836,7 @@ fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: AliasTy<'tcx>) -> Option
                     // Multiple different fn trait impls. Is this even allowed?
                     return None;
                 }
-                output = pred.kind().rebind(p.term.ty()).transpose();
+                output = pred.kind().rebind(p.term.as_type()).transpose();
             },
             _ => (),
         }