c++: ICE with scoped enum in switch condition [PR103825]

c++: ICE with scoped enum in switch condition [PR103825]

Here we ICE when gimplifying

  enum class Type { Pawn };
  struct Piece {
    Type type : 4;
  };
  void foo() {
    switch (Piece().type)
      case Type::Pawn:;
  }

because we ended up with TYPE_PRECISION (cond) < TYPE_PRECISION (case).
That's because the case expr type here is the unlowered type Type,
whereas the conditional's type is the lowered <unnamed-signed:4>.  This
is not supposed to happen: see the comment in pop_switch around the
is_bitfield_expr_with_lowered_type check.

But here we did not revert to the lowered SWITCH_STMT_TYPE, because
the conditional contains a TARGET_EXPR, which has side-effects, which
means that finish_switch_cond -> maybe_cleanup_point_expr wraps it
in a CLEANUP_POINT_EXPR.  And is_bitfield_expr_with_lowered_type does
not see through those.

	PR c++/103825

gcc/cp/ChangeLog:

	* typeck.cc (is_bitfield_expr_with_lowered_type): Handle
	CLEANUP_POINT_EXPR.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/enum44.C: New test.