Don't avoid bool tags anymore to use scalar pairs for tagged enums

Author: nox

src/librustc/ty/layout.rs

@@ -988,13 +988,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                 let mut abi = Abi::Aggregate { sized: true };
                 if tag.value.size(dl) == size {
                     abi = Abi::Scalar(tag.clone());
-                } else if !tag.is_bool() {
-                    // HACK(nox): Blindly using ScalarPair for all tagged enums
-                    // where applicable leads to Option<u8> being handled as {i1, i8},
-                    // which later confuses SROA and some loop optimisations,
-                    // ultimately leading to the repeat-trusted-len test
-                    // failing. We make the trade-off of using ScalarPair only
-                    // for types where the tag isn't a boolean.
+                } else {
                     let mut common_prim = None;
                     for (field_layouts, layout_variant) in variants.iter().zip(&layout_variants) {
                         let offsets = match layout_variant.fields {