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

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt};
   3 use clippy_utils::ty::is_type_diagnostic_item;
   4 use clippy_utils::{is_lang_ctor, path_to_local_id};
   5 use if_chain::if_chain;
   6 use rustc_errors::Applicability;
   7 use rustc_hir::LangItem::{ResultErr, ResultOk};
   8 use rustc_hir::{Closure, Expr, ExprKind, PatKind};
   9 use rustc_lint::LateContext;
  10 use rustc_span::symbol::sym;
  11
  12 use super::MANUAL_OK_OR;
  13
  14 pub(super) fn check<'tcx>(
  15     cx: &LateContext<'tcx>,
  16     expr: &'tcx Expr<'tcx>,
  17     recv: &'tcx Expr<'_>,
  18     or_expr: &'tcx Expr<'_>,
  19     map_expr: &'tcx Expr<'_>,
  20 ) {
  21     if_chain! {
  22         if let Some(method_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
  23         if let Some(impl_id) = cx.tcx.impl_of_method(method_id);
  24         if is_type_diagnostic_item(cx, cx.tcx.type_of(impl_id), sym::Option);
  25         if let ExprKind::Call(Expr { kind: ExprKind::Path(err_path), .. }, [err_arg]) = or_expr.kind;
  26         if is_lang_ctor(cx, err_path, ResultErr);
  27         if is_ok_wrapping(cx, map_expr);
  28         if let Some(recv_snippet) = snippet_opt(cx, recv.span);
  29         if let Some(err_arg_snippet) = snippet_opt(cx, err_arg.span);
  30         if let Some(indent) = indent_of(cx, expr.span);
  31         then {
  32             let reindented_err_arg_snippet = reindent_multiline(err_arg_snippet.into(), true, Some(indent + 4));
  33             span_lint_and_sugg(
  34                 cx,
  35                 MANUAL_OK_OR,
  36                 expr.span,
  37                 "this pattern reimplements `Option::ok_or`",
  38                 "replace with",
  39                 format!(
  40                     "{}.ok_or({})",
  41                     recv_snippet,
  42                     reindented_err_arg_snippet
  43                 ),
  44                 Applicability::MachineApplicable,
  45             );
  46         }
  47     }
  48 }
  49
  50 fn is_ok_wrapping(cx: &LateContext<'_>, map_expr: &Expr<'_>) -> bool {
  51     if let ExprKind::Path(ref qpath) = map_expr.kind {
  52         if is_lang_ctor(cx, qpath, ResultOk) {
  53             return true;
  54         }
  55     }
  56     if_chain! {
  57         if let ExprKind::Closure(&Closure { body, .. }) = map_expr.kind;
  58         let body = cx.tcx.hir().body(body);
  59         if let PatKind::Binding(_, param_id, ..) = body.params[0].pat.kind;
  60         if let ExprKind::Call(Expr { kind: ExprKind::Path(ok_path), .. }, &[ref ok_arg]) = body.value.kind;
  61         if is_lang_ctor(cx, ok_path, ResultOk);
  62         then { path_to_local_id(ok_arg, param_id) } else { false }
  63     }
  64 }