Auto merge of #86456 - JohnTitor:rollup-jjzupny, r=JohnTitor

Rollup of 9 pull requests

Successful merges:

 - #86136 (Stabilize span_open() and span_close().)
 - #86359 (Use as_secs_f64 in JunitFormatter)
 - #86370 (Fix rustdoc stabilized versions layout)
 - #86397 (Alter std::cell::Cell::get_mut documentation)
 - #86407 (Use `map_or` instead of open-coding it)
 - #86425 (Update rustversion to 1.0.5)
 - #86440 (Update library tracking issue for libs-api rename.)
 - #86444 (Fix ICE with `#[repr(simd)]` on enum)
 - #86453 (stdlib: Fix typo in internal RefCell docs )

Failed merges:

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

compiler/rustc_middle/src/ty/layout.rs

@@ -672,6 +672,15 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
             // SIMD vector types.
             ty::Adt(def, substs) if def.repr.simd() => {
+                if !def.is_struct() {
+                    // Should have yielded E0517 by now.
+                    tcx.sess.delay_span_bug(
+                        DUMMY_SP,
+                        "#[repr(simd)] was applied to an ADT that is not a struct",
+                    );
+                    return Err(LayoutError::Unknown(ty));
+                }
+
                 // Supported SIMD vectors are homogeneous ADTs with at least one field:
                 //
                 // * #[repr(simd)] struct S(T, T, T, T);