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()
  },