src/tools/clippy/clippy_lints/src/casts/fn_to_numeric_cast_any.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::source::snippet_with_applicability;
   3 use rustc_errors::Applicability;
   4 use rustc_hir::Expr;
   5 use rustc_lint::LateContext;
   6 use rustc_middle::ty::{self, Ty};
   7
   8 use super::FN_TO_NUMERIC_CAST_ANY;
   9
  10 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
  11     // We allow casts from any function type to any function type.
  12     match cast_to.kind() {
  13         ty::FnDef(..) | ty::FnPtr(..) => return,
  14         _ => { /* continue to checks */ },
  15     }
  16
  17     match cast_from.kind() {
  18         ty::FnDef(..) | ty::FnPtr(_) => {
  19             let mut applicability = Applicability::MaybeIncorrect;
  20             let from_snippet = snippet_with_applicability(cx, cast_expr.span, "..", &mut applicability);
  21
  22             span_lint_and_sugg(
  23                 cx,
  24                 FN_TO_NUMERIC_CAST_ANY,
  25                 expr.span,
  26                 &format!("casting function pointer `{}` to `{}`", from_snippet, cast_to),
  27                 "did you mean to invoke the function?",
  28                 format!("{}() as {}", from_snippet, cast_to),
  29                 applicability,
  30             );
  31         },
  32         _ => {},
  33     }
  34 }