Rollup merge of #100652 - compiler-errors:no-defer-sized-checks, r=TaKO8Ki

Remove deferred sized checks (make them eager)

Improves diagnostics spans... this doesn't seem to be the case anymore:

```rust
// Some additional `Sized` obligations badly affect type inference.
// These obligations are added in a later stage of typeck.
pub(super) deferred_sized_obligations:
        RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
```

compiler/rustc_typeck/src/check/expr.rs

@@ -561,16 +561,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // We just want to check sizedness, so instead of introducing
                     // placeholder lifetimes with probing, we just replace higher lifetimes
                     // with fresh vars.
-                    let span = args.get(i).map(|a| a.span).unwrap_or(expr.span);
+                    let arg_span = args.get(i).map(|a| a.span);
+                    let span = arg_span.unwrap_or(expr.span);
                     let input = self.replace_bound_vars_with_fresh_vars(
                         span,
                         infer::LateBoundRegionConversionTime::FnCall,
                         fn_sig.input(i),
                     );
-                    self.require_type_is_sized_deferred(
-                        input,
+                    self.require_type_is_sized(
+                        self.normalize_associated_types_in(span, input),
                         span,
-                        traits::SizedArgumentType(None),
+                        traits::SizedArgumentType(arg_span),
                     );
                 }
             }
@@ -585,7 +586,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 infer::LateBoundRegionConversionTime::FnCall,
                 fn_sig.output(),
             );
-            self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
+            self.require_type_is_sized(
+                self.normalize_associated_types_in(expr.span, output),
+                expr.span,
+                traits::SizedReturnType,
+            );
         }
 
         // We always require that the type provided as the value for

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -442,17 +442,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    pub fn require_type_is_sized_deferred(
-        &self,
-        ty: Ty<'tcx>,
-        span: Span,
-        code: traits::ObligationCauseCode<'tcx>,
-    ) {
-        if !ty.references_error() {
-            self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
-        }
-    }
-
     pub fn register_bound(
         &self,
         ty: Ty<'tcx>,

compiler/rustc_typeck/src/check/inherited.rs

@@ -35,11 +35,6 @@ pub struct Inherited<'a, 'tcx> {
 
     pub(super) fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
 
-    // Some additional `Sized` obligations badly affect type inference.
-    // These obligations are added in a later stage of typeck.
-    pub(super) deferred_sized_obligations:
-        RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
-
     // When we process a call like `c()` where `c` is a closure type,
     // we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
     // `FnOnce` closure. In that case, we defer full resolution of the
@@ -117,7 +112,6 @@ impl<'a, 'tcx> Inherited<'a, 'tcx> {
             infcx,
             fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
             locals: RefCell::new(Default::default()),
-            deferred_sized_obligations: RefCell::new(Vec::new()),
             deferred_call_resolutions: RefCell::new(Default::default()),
             deferred_cast_checks: RefCell::new(Vec::new()),
             deferred_transmute_checks: RefCell::new(Vec::new()),

compiler/rustc_typeck/src/check/mod.rs

@@ -467,11 +467,6 @@ fn typeck_with_fallback<'tcx>(
         fcx.resolve_rvalue_scopes(def_id.to_def_id());
         fcx.resolve_generator_interiors(def_id.to_def_id());
 
-        for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
-            let ty = fcx.normalize_ty(span, ty);
-            fcx.require_type_is_sized(ty, span, code);
-        }
-
         fcx.select_all_obligations_or_error();
 
         if !fcx.infcx.is_tainted_by_errors() {