fix filter_map_bool_then with a bool reference

Author: kiscad

clippy_lints/src/methods/filter_map_bool_then.rs

@@ -8,7 +8,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LintContext};
 use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::Binder;
+use rustc_middle::ty::{self, Binder};
 use rustc_span::{sym, Span};
 
 pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, arg: &Expr<'_>, call_span: Span) {
@@ -36,6 +36,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, arg: &
         && let Some(def_id) = cx.typeck_results().type_dependent_def_id(value.hir_id)
         && match_def_path(cx, def_id, &BOOL_THEN)
         && !is_from_proc_macro(cx, expr)
+        && let ref_bool = matches!(cx.typeck_results().expr_ty(recv).kind(), ty::Ref(..))
         && let Some(param_snippet) = snippet_opt(cx, param.span)
         && let Some(filter) = snippet_opt(cx, recv.span)
         && let Some(map) = snippet_opt(cx, then_body.span)
@@ -46,7 +47,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, arg: &
             call_span,
             "usage of `bool::then` in `filter_map`",
             "use `filter` then `map` instead",
-            format!("filter(|&{param_snippet}| {filter}).map(|{param_snippet}| {map})"),
+            format!("filter(|&{param_snippet}| {}{filter}).map(|{param_snippet}| {map})", if ref_bool { "*" } else { "" }),
             Applicability::MachineApplicable,
         );
     }

tests/ui/filter_map_bool_then.fixed

@@ -55,3 +55,8 @@ fn main() {
 fn issue11309<'a>(iter: impl Iterator<Item = (&'a str, &'a str)>) -> Vec<&'a str> {
     iter.filter_map(|(_, s): (&str, _)| Some(s)).collect()
 }
+
+fn issue11503() {
+    let bools: &[bool] = &[true, false, false, true];
+    let _: Vec<usize> = bools.iter().enumerate().filter(|&(i, b)| *b).map(|(i, b)| i).collect();
+}

tests/ui/filter_map_bool_then.rs

@@ -55,3 +55,8 @@ fn main() {
 fn issue11309<'a>(iter: impl Iterator<Item = (&'a str, &'a str)>) -> Vec<&'a str> {
     iter.filter_map(|(_, s): (&str, _)| Some(s)).collect()
 }
+
+fn issue11503() {
+    let bools: &[bool] = &[true, false, false, true];
+    let _: Vec<usize> = bools.iter().enumerate().filter_map(|(i, b)| b.then(|| i)).collect();
+}

tests/ui/filter_map_bool_then.stderr

@@ -37,5 +37,11 @@ error: usage of `bool::then` in `filter_map`
 LL |     v.clone().iter().filter_map(|i| (i == &NonCopy).then(|| i));
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `filter` then `map` instead: `filter(|&i| (i == &NonCopy)).map(|i| i)`
 
-error: aborting due to 6 previous errors
+error: usage of `bool::then` in `filter_map`
+  --> $DIR/filter_map_bool_then.rs:61:50
+   |
+LL |     let _: Vec<usize> = bools.iter().enumerate().filter_map(|(i, b)| b.then(|| i)).collect();
+   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `filter` then `map` instead: `filter(|&(i, b)| *b).map(|(i, b)| i)`
+
+error: aborting due to 7 previous errors