Rollup merge of #120270 - compiler-errors:randos, r=lcnr

A bunch of random modifications

r? oli-obk

Kitchen sink of changes that I didn't know where to put elsewhere. Documentation tweaks mostly, but also removing some unreachable code and simplifying the pretty printing for closures/coroutines.

3 files changed, 13 insertions, 35 deletions

diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/weak_types.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/weak_types.rs
index 6d5728797d1..9f91c02c1ab 100644
--- a/compiler/rustc_trait_selection/src/solve/normalizes_to/weak_types.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/weak_types.rs
@@ -1,7 +1,7 @@
 //! Computes a normalizes-to (projection) goal for inherent associated types,
 //! `#![feature(lazy_type_alias)]` and `#![feature(type_alias_impl_trait)]`.
 //!
-//! Since a weak alias is not ambiguous, this just computes the `type_of` of
+//! Since a weak alias is never ambiguous, this just computes the `type_of` of
 //! the alias and registers the where-clauses of the type alias.
 use rustc_middle::traits::solve::{Certainty, Goal, GoalSource, QueryResult};
 use rustc_middle::ty;
diff --git a/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs b/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
index 138bc6129f7..79f03242c58 100644
--- a/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
@@ -232,32 +232,12 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
             Ok::<_, NoSolution>(())
         })?,
 
-        ty::Closure(_, args) => {
-            if !args.as_closure().is_valid() {
-                // By the time this code runs, all type variables ought to
-                // be fully resolved.
-
-                tcx.dcx().span_delayed_bug(
-                    span,
-                    format!("upvar_tys for closure not found. Expected capture information for closure {ty}",),
-                );
-                return Err(NoSolution);
+        ty::Closure(_, args) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
+            for ty in args.as_closure().upvar_tys() {
+                dtorck_constraint_for_ty_inner(tcx, param_env, span, depth + 1, ty, constraints)?;
             }
-
-            rustc_data_structures::stack::ensure_sufficient_stack(|| {
-                for ty in args.as_closure().upvar_tys() {
-                    dtorck_constraint_for_ty_inner(
-                        tcx,
-                        param_env,
-                        span,
-                        depth + 1,
-                        ty,
-                        constraints,
-                    )?;
-                }
-                Ok::<_, NoSolution>(())
-            })?
-        }
+            Ok::<_, NoSolution>(())
+        })?,
 
         ty::Coroutine(_, args) => {
             // rust-lang/rust#49918: types can be constructed, stored
@@ -283,15 +263,6 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
             // derived from lifetimes attached to the upvars and resume
             // argument, and we *do* incorporate those here.
             let args = args.as_coroutine();
-            if !args.is_valid() {
-                // By the time this code runs, all type variables ought to
-                // be fully resolved.
-                tcx.dcx().span_delayed_bug(
-                    span,
-                    format!("upvar_tys for coroutine not found. Expected capture information for coroutine {ty}",),
-                );
-                return Err(NoSolution);
-            }
 
             // While we conservatively assume that all coroutines require drop
             // to avoid query cycles during MIR building, we can check the actual
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
index 957de925dd3..fb09f094d37 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
@@ -141,6 +141,13 @@ where
         infcx: &InferCtxt<'tcx>,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
+        // In the new trait solver, query type ops are performed locally. This
+        // is because query type ops currently use the old canonicalizer, and
+        // that doesn't preserve things like opaques which have been registered
+        // during MIR typeck. Even after the old canonicalizer is gone, it's
+        // probably worthwhile just keeping this run-locally logic, since we
+        // probably don't gain much from caching here given the new solver does
+        // caching internally.
         if infcx.next_trait_solver() {
             return Ok(scrape_region_constraints(
                 infcx,