1 use crate::utils::usage::mutated_variables;
2 use crate::utils::{is_type_diagnostic_item, meets_msrv, snippet, span_lint, span_lint_and_sugg};
3 use rustc_errors::Applicability;
5 use rustc_lint::LateContext;
6 use rustc_semver::RustcVersion;
7 use rustc_span::symbol::sym;
9 use super::MAP_UNWRAP_OR;
11 const MAP_UNWRAP_OR_MSRV: RustcVersion = RustcVersion::new(1, 41, 0);
13 /// lint use of `map().unwrap_or_else()` for `Option`s and `Result`s
14 /// Return true if lint triggered
15 pub(super) fn check<'tcx>(
16 cx: &LateContext<'tcx>,
17 expr: &'tcx hir::Expr<'_>,
18 map_args: &'tcx [hir::Expr<'_>],
19 unwrap_args: &'tcx [hir::Expr<'_>],
20 msrv: Option<&RustcVersion>,
22 if !meets_msrv(msrv, &MAP_UNWRAP_OR_MSRV) {
25 // lint if the caller of `map()` is an `Option`
26 let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym::option_type);
27 let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym::result_type);
29 if is_option || is_result {
30 // Don't make a suggestion that may fail to compile due to mutably borrowing
31 // the same variable twice.
32 let map_mutated_vars = mutated_variables(&map_args[0], cx);
33 let unwrap_mutated_vars = mutated_variables(&unwrap_args[1], cx);
34 if let (Some(map_mutated_vars), Some(unwrap_mutated_vars)) = (map_mutated_vars, unwrap_mutated_vars) {
35 if map_mutated_vars.intersection(&unwrap_mutated_vars).next().is_some() {
43 let msg = if is_option {
44 "called `map(<f>).unwrap_or_else(<g>)` on an `Option` value. This can be done more directly by calling \
45 `map_or_else(<g>, <f>)` instead"
47 "called `map(<f>).unwrap_or_else(<g>)` on a `Result` value. This can be done more directly by calling \
48 `.map_or_else(<g>, <f>)` instead"
50 // get snippets for args to map() and unwrap_or_else()
51 let map_snippet = snippet(cx, map_args[1].span, "..");
52 let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
53 // lint, with note if neither arg is > 1 line and both map() and
54 // unwrap_or_else() have the same span
55 let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
56 let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
57 if same_span && !multiline {
58 let var_snippet = snippet(cx, map_args[0].span, "..");
65 format!("{}.map_or_else({}, {})", var_snippet, unwrap_snippet, map_snippet),
66 Applicability::MachineApplicable,
69 } else if same_span && multiline {
70 span_lint(cx, MAP_UNWRAP_OR, expr.span, msg);