Auto merge of #120401 - matthiaskrgr:rollup-7740vrx, r=matthiaskrgr

Rollup of 12 pull requests

Successful merges:

 - #103522 (stabilise array methods)
 - #113489 (impl `From<&[T; N]>` for `Cow<[T]>`)
 - #119342 (Emit suggestion when trying to write exclusive ranges as `..<`)
 - #119562 (Rename `pointer` field on `Pin`)
 - #119800 (Document `rustc_index::vec::IndexVec`)
 - #120205 (std: make `HEAP` initializer never inline)
 - #120277 (Normalize field types before checking validity)
 - #120311 (core: add `From<core::ascii::Char>` implementations)
 - #120366 (mark a doctest with UB as no_run)
 - #120378 (always normalize `LoweredTy` in the new solver)
 - #120382 (Classify closure arguments in refutable pattern in argument error)
 - #120389 (Add fmease to the compiler review rotation)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_const_eval/src/transform/validate.rs

@@ -810,13 +810,18 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     let adt_def = self.tcx.adt_def(def_id);
                     assert!(adt_def.is_union());
                     assert_eq!(idx, FIRST_VARIANT);
-                    let dest = adt_def.non_enum_variant().fields[field].ty(self.tcx, args);
-                    if fields.len() != 1 {
+                    let dest_ty = self.tcx.normalize_erasing_regions(
+                        self.param_env,
+                        adt_def.non_enum_variant().fields[field].ty(self.tcx, args),
+                    );
+                    if fields.len() == 1 {
+                        let src_ty = fields.raw[0].ty(self.body, self.tcx);
+                        if !self.mir_assign_valid_types(src_ty, dest_ty) {
+                            self.fail(location, "union field has the wrong type");
+                        }
+                    } else {
                         self.fail(location, "unions should have one initialized field");
                     }
-                    if !self.mir_assign_valid_types(fields.raw[0].ty(self.body, self.tcx), dest) {
-                        self.fail(location, "union field has the wrong type");
-                    }
                 }
                 AggregateKind::Adt(def_id, idx, args, _, None) => {
                     let adt_def = self.tcx.adt_def(def_id);
@@ -826,10 +831,10 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                         self.fail(location, "adt has the wrong number of initialized fields");
                     }
                     for (src, dest) in std::iter::zip(fields, &variant.fields) {
-                        if !self.mir_assign_valid_types(
-                            src.ty(self.body, self.tcx),
-                            dest.ty(self.tcx, args),
-                        ) {
+                        let dest_ty = self
+                            .tcx
+                            .normalize_erasing_regions(self.param_env, dest.ty(self.tcx, args));
+                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest_ty) {
                             self.fail(location, "adt field has the wrong type");
                         }
                     }

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -369,6 +369,14 @@ pub struct LoweredTy<'tcx> {
 
 impl<'tcx> LoweredTy<'tcx> {
     pub fn from_raw(fcx: &FnCtxt<'_, 'tcx>, span: Span, raw: Ty<'tcx>) -> LoweredTy<'tcx> {
-        LoweredTy { raw, normalized: fcx.normalize(span, raw) }
+        // FIXME(-Znext-solver): We're still figuring out how to best handle
+        // normalization and this doesn't feel too great. We should look at this
+        // code again before stabilizing it.
+        let normalized = if fcx.next_trait_solver() {
+            fcx.try_structurally_resolve_type(span, raw)
+        } else {
+            fcx.normalize(span, raw)
+        };
+        LoweredTy { raw, normalized }
     }
 }