src/tools/clippy/clippy_lints/src/methods/filetype_is_file.rs

   1 use clippy_utils::diagnostics::span_lint_and_help;
   2 use clippy_utils::ty::match_type;
   3 use clippy_utils::{get_parent_expr, paths};
   4 use if_chain::if_chain;
   5 use rustc_hir as hir;
   6 use rustc_lint::LateContext;
   7 use rustc_span::source_map::Span;
   8
   9 use super::FILETYPE_IS_FILE;
  10
  11 pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>) {
  12     let ty = cx.typeck_results().expr_ty(recv);
  13
  14     if !match_type(cx, ty, &paths::FILE_TYPE) {
  15         return;
  16     }
  17
  18     let span: Span;
  19     let verb: &str;
  20     let lint_unary: &str;
  21     let help_unary: &str;
  22     if_chain! {
  23         if let Some(parent) = get_parent_expr(cx, expr);
  24         if let hir::ExprKind::Unary(op, _) = parent.kind;
  25         if op == hir::UnOp::Not;
  26         then {
  27             lint_unary = "!";
  28             verb = "denies";
  29             help_unary = "";
  30             span = parent.span;
  31         } else {
  32             lint_unary = "";
  33             verb = "covers";
  34             help_unary = "!";
  35             span = expr.span;
  36         }
  37     }
  38     let lint_msg = format!("`{}FileType::is_file()` only {} regular files", lint_unary, verb);
  39     let help_msg = format!("use `{}FileType::is_dir()` instead", help_unary);
  40     span_lint_and_help(cx, FILETYPE_IS_FILE, span, &lint_msg, None, &help_msg);
  41 }