Rollup merge of rust-lang#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

Author: fmease

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

@@ -2250,7 +2250,7 @@ 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

@@ -436,7 +436,9 @@ 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

@@ -158,7 +158,7 @@ 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

@@ -626,14 +626,22 @@ 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(),