Warn about hidden_lifetimes_in_output_paths by default

Author: shepmaster

compiler/rustc_lint/src/lifetime_style.rs

@@ -136,7 +136,7 @@ declare_lint! {
     ///
     /// [placeholder lifetime]: https://doc.rust-lang.org/reference/lifetime-elision.html#lifetime-elision-in-functions
     pub HIDDEN_LIFETIMES_IN_OUTPUT_PATHS,
-    Allow,
+    Warn,
     "hidden lifetime parameters in types in function return values are deprecated"
 }
 

tests/ui/associated-types/associated-types-impl-redirect.rs

@@ -21,7 +21,7 @@ trait Iterator {
 }
 
 trait IteratorExt: Iterator + Sized {
-    fn by_ref(&mut self) -> ByRef<Self> {
+    fn by_ref(&mut self) -> ByRef<'_, Self> {
         ByRef(self)
     }
 }

tests/ui/associated-types/associated-types-normalize-in-bounds-ufcs.rs

@@ -21,11 +21,11 @@ trait SliceExt2 {
 impl<T> SliceExt2 for [T] {
     type Item = T;
 
-    fn split2<P>(&self, pred: P) -> Splits<T, P> where P: FnMut(&T) -> bool {
+    fn split2<P>(&self, pred: P) -> Splits<'_, T, P> where P: FnMut(&T) -> bool {
         loop {}
     }
 
-    fn splitn2<P>(&self, n: u32, pred: P) -> SplitsN<Splits<T, P>> where P: FnMut(&T) -> bool {
+    fn splitn2<P>(&self, n: u32, pred: P) -> SplitsN<Splits<'_, T, P>> where P: FnMut(&T) -> bool {
         SliceExt2::split2(self, pred);
         loop {}
     }

tests/ui/associated-types/associated-types-normalize-in-bounds.rs

@@ -21,11 +21,17 @@ trait SliceExt2 {
 impl<T> SliceExt2 for [T] {
     type Item = T;
 
-    fn split2<P>(&self, pred: P) -> Splits<T, P> where P: FnMut(&T) -> bool {
+    fn split2<P>(&self, pred: P) -> Splits<'_, T, P>
+    where
+        P: FnMut(&T) -> bool,
+    {
         loop {}
     }
 
-    fn splitn2<P>(&self, n: usize, pred: P) -> SplitsN<Splits<T, P>> where P: FnMut(&T) -> bool {
+    fn splitn2<P>(&self, n: usize, pred: P) -> SplitsN<Splits<'_, T, P>>
+    where
+        P: FnMut(&T) -> bool,
+    {
         self.split2(pred);
         loop {}
     }

tests/ui/associated-types/associated-types-where-clause-impl-ambiguity.rs

@@ -20,7 +20,7 @@ trait Iterator {
 }
 
 trait IteratorExt: Iterator + Sized {
-    fn by_ref(&mut self) -> ByRef<Self> {
+    fn by_ref(&mut self) -> ByRef<'_, Self> {
         ByRef(self)
     }
 }

tests/ui/associated-types/cache/elision.rs

@@ -1,3 +1,5 @@
+#![allow(hidden_lifetimes_in_output_paths)]
+
 // Check that you are allowed to implement using elision but write
 // trait without elision (a bug in this cropped up during
 // bootstrapping, so this is a regression test).

tests/ui/associated-types/project-defer-unification.rs

@@ -50,7 +50,7 @@ where P: Pixel + 'static,
         loop { }
     }
 
-    pub fn pixels_mut(&mut self) -> PixelsMut<P> {
+    pub fn pixels_mut(&mut self) -> PixelsMut<'_, P> {
         loop { }
     }
 }

tests/ui/borrowck/copy-suggestion-region-vid.fixed

@@ -7,7 +7,7 @@ pub struct HelperStruct<'n> {
 }
 
 impl DataStruct {
-    pub fn f(&self) -> HelperStruct {
+    pub fn f(&self) -> HelperStruct<'_> {
         let helpers = [vec![], vec![]];
 
         HelperStruct { helpers: helpers.clone(), is_empty: helpers[0].is_empty() }

tests/ui/borrowck/copy-suggestion-region-vid.rs

@@ -7,7 +7,7 @@ pub struct HelperStruct<'n> {
 }
 
 impl DataStruct {
-    pub fn f(&self) -> HelperStruct {
+    pub fn f(&self) -> HelperStruct<'_> {
         let helpers = [vec![], vec![]];
 
         HelperStruct { helpers, is_empty: helpers[0].is_empty() }