Add more receivers to useless_conversion

- `ControlFlow::map_break()`
- `ControlFlow::map_continue()`
- `Iterator::map()`

Author: samueltardieu

clippy_lints/src/methods/mod.rs

@@ -4984,6 +4984,9 @@ impl Methods {
                     manual_inspect::check(cx, expr, m_arg, name, span, &self.msrv);
                     crate::useless_conversion::check_function_application(cx, expr, recv, m_arg);
                 },
+                ("map_break" | "map_continue", [m_arg]) => {
+                    crate::useless_conversion::check_function_application(cx, expr, recv, m_arg);
+                },
                 ("map_or", [def, map]) => {
                     option_map_or_none::check(cx, expr, recv, def, map);
                     manual_ok_or::check(cx, expr, recv, def, map);

clippy_lints/src/useless_conversion.rs

@@ -14,7 +14,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::{self, AdtDef, EarlyBinder, GenericArg, GenericArgsRef, Ty, TypeVisitableExt};
 use rustc_session::impl_lint_pass;
-use rustc_span::{Span, sym};
+use rustc_span::{Span, Symbol, sym};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 
 declare_clippy_lint! {
@@ -415,9 +415,25 @@ fn has_eligible_receiver(cx: &LateContext<'_>, recv: &Expr<'_>, expr: &Expr<'_>)
     let recv_ty = cx.typeck_results().expr_ty(recv);
     if is_inherent_method_call(cx, expr)
         && let Some(recv_ty_defid) = recv_ty.ty_adt_def().map(AdtDef::did)
-        && let Some(diag_name) = cx.tcx.get_diagnostic_name(recv_ty_defid)
-        && matches!(diag_name, sym::Option | sym::Result)
     {
+        if let Some(diag_name) = cx.tcx.get_diagnostic_name(recv_ty_defid)
+            && matches!(diag_name, sym::Option | sym::Result)
+        {
+            return true;
+        }
+
+        // FIXME: Add ControlFlow diagnostic item
+        let def_path = cx.get_def_path(recv_ty_defid);
+        if def_path
+            .iter()
+            .map(Symbol::as_str)
+            .zip(["core", "ops", "control_flow", "ControlFlow"])
+            .all(|(sym, s)| sym == s)
+        {
+            return true;
+        }
+    }
+    if is_trait_method(cx, expr, sym::Iterator) {
         return true;
     }
     false

tests/ui/useless_conversion.fixed

@@ -3,6 +3,8 @@
 // FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
 #![allow(static_mut_refs)]
 
+use std::ops::ControlFlow;
+
 fn test_generic<T: Copy>(val: T) -> T {
     let _ = val;
     val
@@ -308,6 +310,13 @@ fn direct_application() {
     let _: Result<(), std::io::Error> = test_issue_3913();
     //~^ useless_conversion
 
+    let c: ControlFlow<()> = ControlFlow::Continue(());
+    let _: ControlFlow<()> = c;
+    //~^ useless_conversion
+    let c: ControlFlow<()> = ControlFlow::Continue(());
+    let _: ControlFlow<()> = c;
+    //~^ useless_conversion
+
     struct Absorb;
     impl From<()> for Absorb {
         fn from(_: ()) -> Self {
@@ -319,11 +328,17 @@ fn direct_application() {
             Self
         }
     }
+    let _: Vec<u32> = [1u32].into_iter().collect();
+    //~^ useless_conversion
 
     // No lint for those
     let _: Result<Absorb, std::io::Error> = test_issue_3913().map(Into::into);
     let _: Result<(), Absorb> = test_issue_3913().map_err(Into::into);
     let _: Result<Absorb, std::io::Error> = test_issue_3913().map(From::from);
     let _: Result<(), Absorb> = test_issue_3913().map_err(From::from);
-    let _: Vec<u32> = [1u32].into_iter().map(Into::into).collect();
+}
+
+fn gen_identity<T>(x: [T; 3]) -> Vec<T> {
+    x.into_iter().collect()
+    //~^ useless_conversion
 }

tests/ui/useless_conversion.rs

@@ -3,6 +3,8 @@
 // FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
 #![allow(static_mut_refs)]
 
+use std::ops::ControlFlow;
+
 fn test_generic<T: Copy>(val: T) -> T {
     let _ = T::from(val);
     val.into()
@@ -308,6 +310,13 @@ fn direct_application() {
     let _: Result<(), std::io::Error> = test_issue_3913().map_err(From::from);
     //~^ useless_conversion
 
+    let c: ControlFlow<()> = ControlFlow::Continue(());
+    let _: ControlFlow<()> = c.map_break(Into::into);
+    //~^ useless_conversion
+    let c: ControlFlow<()> = ControlFlow::Continue(());
+    let _: ControlFlow<()> = c.map_continue(Into::into);
+    //~^ useless_conversion
+
     struct Absorb;
     impl From<()> for Absorb {
         fn from(_: ()) -> Self {
@@ -319,11 +328,17 @@ fn direct_application() {
             Self
         }
     }
+    let _: Vec<u32> = [1u32].into_iter().map(Into::into).collect();
+    //~^ useless_conversion
 
     // No lint for those
     let _: Result<Absorb, std::io::Error> = test_issue_3913().map(Into::into);
     let _: Result<(), Absorb> = test_issue_3913().map_err(Into::into);
     let _: Result<Absorb, std::io::Error> = test_issue_3913().map(From::from);
     let _: Result<(), Absorb> = test_issue_3913().map_err(From::from);
-    let _: Vec<u32> = [1u32].into_iter().map(Into::into).collect();
+}
+
+fn gen_identity<T>(x: [T; 3]) -> Vec<T> {
+    x.into_iter().map(Into::into).collect()
+    //~^ useless_conversion
 }