add check that iterators are not returned

lints/par_iter/src/lib.rs

@@ -23,7 +23,8 @@ use rustc_hir::intravisit::Visitor;
 use rustc_hir::{self as hir};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::ty::{self, ty_kind::TyKind, Ty};
-use utils::{check_implements_par_iter, generate_suggestion, is_type_valid};
+use rustc_span::sym;
+use utils::{check_implements_par_iter, check_trait_impl, generate_suggestion, is_type_valid};
 use variable_check::check_variables;
 
 dylint_linting::declare_late_lint! {
@@ -111,6 +112,10 @@ impl<'tcx> LateLintPass<'tcx> for ParIter {
                 }
 
                 let ty: Ty<'_> = cx.typeck_results().expr_ty(top_expr);
+                // TODO: find a way to deal with iterators returns
+                if check_trait_impl(cx, ty, sym::Iterator) {
+                    return;
+                }
 
                 // TODO: this needs to change and find a better solutions for returns
                 if let TyKind::Adt(_, _) = ty.kind() {

lints/par_iter/src/utils.rs

@@ -41,7 +41,11 @@ pub(crate) fn check_implements_par_iter<'tcx>(
     implemented_traits
 }
 
-fn check_trait_impl<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, trait_name: Symbol) -> bool {
+pub(crate) fn check_trait_impl<'tcx>(
+    cx: &LateContext<'tcx>,
+    ty: Ty<'tcx>,
+    trait_name: Symbol,
+) -> bool {
     cx.tcx
         .get_diagnostic_item(trait_name)
         .map_or(false, |trait_id| implements_trait(cx, ty, trait_id, &[]))

lints/par_iter/ui/main.fixed

@@ -27,6 +27,16 @@ struct Case {
     priority: u32,
 }
 
+#[derive(Clone)]
+struct QosCase {
+    uid: u64, // Identifier for the Quality of Service case
+}
+
+struct ApplicationState {
+    foreground_high_qos_cases: Vec<QosCase>,
+    background_high_qos_cases: Vec<QosCase>,
+}
+
 fn main() {}
 
 // should parallelize
@@ -318,3 +328,15 @@ fn request_request_filter() {
     println!("Downgrade case: {:?}", down_grade_case);
     println!("Swap case index: {:?}", swap_case_index_opt);
 }
+
+// no
+impl ApplicationState {
+    fn transition_to_background(&mut self, target_uid: u64) {
+        let change_state_cases = self
+            .background_high_qos_cases
+            .iter()
+            .cloned()
+            .filter(|case| case.uid == target_uid);
+        self.foreground_high_qos_cases.extend(change_state_cases);
+    }
+}

lints/par_iter/ui/main.rs

@@ -27,6 +27,16 @@ struct Case {
     priority: u32,
 }
 
+#[derive(Clone)]
+struct QosCase {
+    uid: u64, // Identifier for the Quality of Service case
+}
+
+struct ApplicationState {
+    foreground_high_qos_cases: Vec<QosCase>,
+    background_high_qos_cases: Vec<QosCase>,
+}
+
 fn main() {}
 
 // should parallelize
@@ -318,3 +328,15 @@ fn request_request_filter() {
     println!("Downgrade case: {:?}", down_grade_case);
     println!("Swap case index: {:?}", swap_case_index_opt);
 }
+
+// no
+impl ApplicationState {
+    fn transition_to_background(&mut self, target_uid: u64) {
+        let change_state_cases = self
+            .background_high_qos_cases
+            .iter()
+            .cloned()
+            .filter(|case| case.uid == target_uid);
+        self.foreground_high_qos_cases.extend(change_state_cases);
+    }
+}

lints/par_iter/ui/main.stderr

@@ -1,5 +1,5 @@
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:34:5
+  --> $DIR/main.rs:44:5
    |
 LL |     (0..100).into_iter().for_each(|x| println!("{:?}", x));
    |     ^^^^^^^^^^^^^^^^^^^^ help: try using a parallel iterator: `(0..100).into_par_iter()`
@@ -8,7 +8,7 @@ LL |     (0..100).into_iter().for_each(|x| println!("{:?}", x));
    = help: to override `-D warnings` add `#[allow(par_iter)]`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:58:5
+  --> $DIR/main.rs:68:5
    |
 LL | /     (0..100)
 LL | |         .into_iter()
@@ -21,37 +21,37 @@ LL +         .into_par_iter()
    |
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:93:5
+  --> $DIR/main.rs:103:5
    |
 LL |     list.into_iter().for_each(|x| println!("{:?}", x));
    |     ^^^^^^^^^^^^^^^^ help: try using a parallel iterator: `list.into_par_iter()`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:109:5
+  --> $DIR/main.rs:119:5
    |
 LL |     (0..10).into_iter().for_each(|x| {
    |     ^^^^^^^^^^^^^^^^^^^ help: try using a parallel iterator: `(0..10).into_par_iter()`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:192:5
+  --> $DIR/main.rs:202:5
    |
 LL |     data.iter()
    |     ^^^^^^^^^^^ help: try using a parallel iterator: `data.par_iter()`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:219:5
+  --> $DIR/main.rs:229:5
    |
 LL |     numbers.iter().enumerate().for_each(|t| {
    |     ^^^^^^^^^^^^^^ help: try using a parallel iterator: `numbers.par_iter()`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:260:30
+  --> $DIR/main.rs:270:30
    |
 LL |     let names: Vec<String> = people.iter().map(|p| p.name.clone()).collect();
    |                              ^^^^^^^^^^^^^ help: try using a parallel iterator: `people.par_iter()`
 
 error: found iterator that can be parallelized
-  --> $DIR/main.rs:268:37
+  --> $DIR/main.rs:278:37
    |
 LL |       let doubled_numbers: Vec<i32> = numbers
    |  _____________________________________^