clippy_lints/src/transmute/transmute_int_to_float.rs

   1 use super::TRANSMUTE_INT_TO_FLOAT;
   2 use crate::utils::{span_lint_and_then, sugg};
   3 use rustc_errors::Applicability;
   4 use rustc_hir::Expr;
   5 use rustc_lint::LateContext;
   6 use rustc_middle::ty::{self, Ty};
   7
   8 /// Checks for `transmute_int_to_float` lint.
   9 /// Returns `true` if it's triggered, otherwise returns `false`.
  10 pub(super) fn check<'tcx>(
  11     cx: &LateContext<'tcx>,
  12     e: &'tcx Expr<'_>,
  13     from_ty: Ty<'tcx>,
  14     to_ty: Ty<'tcx>,
  15     args: &'tcx [Expr<'_>],
  16     const_context: bool,
  17 ) -> bool {
  18     match (&from_ty.kind(), &to_ty.kind()) {
  19         (ty::Int(_) | ty::Uint(_), ty::Float(_)) if !const_context => {
  20             span_lint_and_then(
  21                 cx,
  22                 TRANSMUTE_INT_TO_FLOAT,
  23                 e.span,
  24                 &format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
  25                 |diag| {
  26                     let arg = sugg::Sugg::hir(cx, &args[0], "..");
  27                     let arg = if let ty::Int(int_ty) = from_ty.kind() {
  28                         arg.as_ty(format!(
  29                             "u{}",
  30                             int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
  31                         ))
  32                     } else {
  33                         arg
  34                     };
  35                     diag.span_suggestion(
  36                         e.span,
  37                         "consider using",
  38                         format!("{}::from_bits({})", to_ty, arg.to_string()),
  39                         Applicability::Unspecified,
  40                     );
  41                 },
  42             );
  43             true
  44         },
  45         _ => false,
  46     }
  47 }