clippy_lints/src/transmute/transmute_int_to_float.rs

   1 use super::TRANSMUTE_INT_TO_FLOAT;
   2 use crate::utils::sugg;
   3 use clippy_utils::diagnostics::span_lint_and_then;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::Expr;
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::{self, Ty};
   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(_)) if !const_context => {
  21             span_lint_and_then(
  22                 cx,
  23                 TRANSMUTE_INT_TO_FLOAT,
  24                 e.span,
  25                 &format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
  26                 |diag| {
  27                     let arg = sugg::Sugg::hir(cx, &args[0], "..");
  28                     let arg = if let ty::Int(int_ty) = from_ty.kind() {
  29                         arg.as_ty(format!(
  30                             "u{}",
  31                             int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
  32                         ))
  33                     } else {
  34                         arg
  35                     };
  36                     diag.span_suggestion(
  37                         e.span,
  38                         "consider using",
  39                         format!("{}::from_bits({})", to_ty, arg.to_string()),
  40                         Applicability::Unspecified,
  41                     );
  42                 },
  43             );
  44             true
  45         },
  46         _ => false,
  47     }
  48 }