Remove some dead code

Author: oli-obk

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -369,13 +369,6 @@ impl<'tcx> ConstToPat<'tcx> {
                 suffix: Box::new([]),
             },
             ty::Ref(_, pointee_ty, ..) => match *pointee_ty.kind() {
-                // These are not allowed and will error elsewhere anyway.
-                ty::Dynamic(..) => {
-                    self.saw_const_match_error.set(true);
-                    let err = InvalidPattern { span, non_sm_ty: ty };
-                    tcx.sess.emit_err(err);
-                    PatKind::Wild
-                }
                 // `&str` is represented as a valtree, let's keep using this
                 // optimization for now.
                 ty::Str => PatKind::Constant { value: mir::ConstantKind::Ty(tcx.mk_const(cv, ty)) },
@@ -467,6 +460,7 @@ impl<'tcx> ConstToPat<'tcx> {
                         let err = UnsizedPattern { span, non_sm_ty: *pointee_ty };
                         tcx.sess.emit_err(err);
 
+                        // FIXME: introduce PatKind::Error to silence follow up diagnostics due to unreachable patterns.
                         PatKind::Wild
                     } else {
                         let old = self.behind_reference.replace(true);

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -53,11 +53,11 @@ use smallvec::{smallvec, SmallVec};
 use rustc_data_structures::captures::Captures;
 use rustc_hir::{HirId, RangeEnd};
 use rustc_index::Idx;
+use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::mir;
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
-use rustc_middle::{middle::stability::EvalResult, mir::interpret::ConstValue};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Integer, Size, VariantIdx, FIRST_VARIANT};
@@ -142,13 +142,6 @@ impl IntRange {
         let ty = value.ty();
         if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, ty) {
             let val = match value {
-                mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) => {
-                    // For this specific pattern we can skip a lot of effort and go
-                    // straight to the result, after doing a bit of checking. (We
-                    // could remove this branch and just fall through, which
-                    // is more general but much slower.)
-                    scalar.to_bits_or_ptr_internal(target_size).unwrap().left()
-                }
                 mir::ConstantKind::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => {
                     valtree.unwrap_leaf().to_bits(target_size).ok()
                 },