clippy_lints/src/transmute/transmute_num_to_bytes.rs

   1 use super::TRANSMUTE_NUM_TO_BYTES;
   2 use clippy_utils::diagnostics::span_lint_and_then;
   3 use clippy_utils::sugg;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::Expr;
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::{self, Ty, UintTy};
   8
   9 /// Checks for `transmute_int_to_float` lint.
  10 /// Returns `true` if it's triggered, otherwise returns `false`.
  11 pub(super) fn check<'tcx>(
  12     cx: &LateContext<'tcx>,
  13     e: &'tcx Expr<'_>,
  14     from_ty: Ty<'tcx>,
  15     to_ty: Ty<'tcx>,
  16     args: &'tcx [Expr<'_>],
  17     const_context: bool,
  18 ) -> bool {
  19     match (&from_ty.kind(), &to_ty.kind()) {
  20         (ty::Int(_) | ty::Uint(_) | ty::Float(_), ty::Array(arr_ty, _)) => {
  21             if !matches!(arr_ty.kind(), ty::Uint(UintTy::U8)) {
  22                 return false;
  23             }
  24             if matches!(from_ty.kind(), ty::Float(_)) && const_context {
  25                 // TODO: Remove when const_float_bits_conv is stabilized
  26                 // rust#72447
  27                 return false;
  28             }
  29
  30             span_lint_and_then(
  31                 cx,
  32                 TRANSMUTE_NUM_TO_BYTES,
  33                 e.span,
  34                 &format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
  35                 |diag| {
  36                     let arg = sugg::Sugg::hir(cx, &args[0], "..");
  37                     diag.span_suggestion(
  38                         e.span,
  39                         "consider using `to_ne_bytes()`",
  40                         format!("{}.to_ne_bytes()", arg),
  41                         Applicability::Unspecified,
  42                     );
  43                 },
  44             );
  45             true
  46         },
  47         _ => false,
  48     }
  49 }