Rollup merge of rust-lang#73586 - RalfJung:switch-ty, r=oli-obk

switch_ty is redundant

This field is redundant, but we cannot remove it currently as pretty-printing relies on it (and it does not have access to `mir::Body` to compute the type itself).

Cc @oli-obk @matthewjasper @jonas-schievink

src/librustc_codegen_ssa/mir/block.rs

@@ -200,6 +200,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
  targets: &Vec<mir::BasicBlock>,
  ) {
  let discr = self.codegen_operand(&mut bx, &discr);
+ // `switch_ty` is redundant, sanity-check that.
+ assert_eq!(discr.layout.ty, switch_ty);
  if targets.len() == 2 {
  // If there are two targets, emit br instead of switch
  let lltrue = helper.llblock(self, targets[0]);

src/librustc_middle/mir/mod.rs

@@ -1075,6 +1075,8 @@ pub enum TerminatorKind<'tcx> {
  discr: Operand<'tcx>,
 
  /// The type of value being tested.
+ /// This is always the same as the type of `discr`.
+ /// FIXME: remove this redundant information. Currently, it is relied on by pretty-printing.
  switch_ty: Ty<'tcx>,
 
  /// Possible values. The locations to branch to in each case

src/librustc_mir/interpret/terminator.rs

@@ -24,9 +24,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
  Goto { target } => self.go_to_block(target),
 
- SwitchInt { ref discr, ref values, ref targets, .. } => {
+ SwitchInt { ref discr, ref values, ref targets, switch_ty } => {
  let discr = self.read_immediate(self.eval_operand(discr, None)?)?;
  trace!("SwitchInt({:?})", *discr);
+ assert_eq!(discr.layout.ty, switch_ty);
 
  // Branch to the `otherwise` case by default, if no match is found.
  assert!(!targets.is_empty());
@@ -50,14 +51,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  self.go_to_block(target_block);
  }
 
- Call {
- ref func,
- ref args,
- destination,
- ref cleanup,
- from_hir_call: _from_hir_call,
- fn_span: _,
- } => {
+ Call { ref func, ref args, destination, ref cleanup, from_hir_call: _, fn_span: _ } => {
  let old_stack = self.frame_idx();
  let old_loc = self.frame().loc;
  let func = self.eval_operand(func, None)?;

src/librustc_mir/transform/validate.rs

@@ -121,7 +121,17 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
  TerminatorKind::Goto { target } => {
  self.check_edge(location, *target, EdgeKind::Normal);
  }
- TerminatorKind::SwitchInt { targets, values, .. } => {
+ TerminatorKind::SwitchInt { targets, values, switch_ty, discr } => {
+ let ty = discr.ty(&self.body.local_decls, self.tcx);
+ if ty != *switch_ty {
+ self.fail(
+ location,
+ format!(
+ "encountered `SwitchInt` terminator with type mismatch: {:?} != {:?}",
+ ty, switch_ty,
+ ),
+ );
+ }
  if targets.len() != values.len() + 1 {
  self.fail(
  location,