Auto merge of rust-lang#82053 - JohnTitor:rollup-ymi9q0g, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - rust-lang#81811 (Fix doc test for Vec::retain(), now passes clippy::eval_order_dependence)
 - rust-lang#81900 (Organize trait test files)
 - rust-lang#81995 (Fix suggestion to introduce explicit lifetime)
 - rust-lang#82031 (Drop an unnecessary intermediate variable)
 - rust-lang#82033 (Refactor `get_word_attr` to return only `Option`)
 - rust-lang#82040 (Add test to prevent src link regression)
 - rust-lang#82041 (Add docs for shared_from_slice From impls)
 - rust-lang#82050 (Added tests to drain an empty vec)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2248,13 +2248,18 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     "...",
                 );
                 if let Some(infer::RelateParamBound(_, t)) = origin {
+                    let return_impl_trait = self
+                        .in_progress_typeck_results
+                        .map(|typeck_results| typeck_results.borrow().hir_owner)
+                        .and_then(|owner| self.tcx.return_type_impl_trait(owner))
+                        .is_some();
                     let t = self.resolve_vars_if_possible(t);
                     match t.kind() {
                         // We've got:
                         // fn get_later<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
                         // suggest:
                         // fn get_later<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
-                        ty::Closure(_, _substs) | ty::Opaque(_, _substs) => {
+                        ty::Closure(_, _substs) | ty::Opaque(_, _substs) if return_impl_trait => {
                             new_binding_suggestion(&mut err, type_param_span, bound_kind);
                         }
                         _ => {

compiler/rustc_typeck/src/check/upvar.rs

@@ -260,8 +260,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // local crate or were inlined into it along with some function.
         // This may change if abstract return types of some sort are
         // implemented.
-        let tcx = self.tcx;
-
         self.typeck_results
             .borrow()
             .closure_min_captures_flattened(closure_id)
@@ -276,7 +274,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
                 match capture {
                     ty::UpvarCapture::ByValue(_) => upvar_ty,
-                    ty::UpvarCapture::ByRef(borrow) => tcx.mk_ref(
+                    ty::UpvarCapture::ByRef(borrow) => self.tcx.mk_ref(
                         borrow.region,
                         ty::TypeAndMut { ty: upvar_ty, mutbl: borrow.kind.to_mutbl_lossy() },
                     ),

library/alloc/src/rc.rs

@@ -1652,6 +1652,16 @@ impl<T> From<T> for Rc<T> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T: Clone> From<&[T]> for Rc<[T]> {
+    /// Allocate a reference-counted slice and fill it by cloning `v`'s items.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::rc::Rc;
+    /// let original: &[i32] = &[1, 2, 3];
+    /// let shared: Rc<[i32]> = Rc::from(original);
+    /// assert_eq!(&[1, 2, 3], &shared[..]);
+    /// ```
     #[inline]
     fn from(v: &[T]) -> Rc<[T]> {
         <Self as RcFromSlice<T>>::from_slice(v)
@@ -1660,6 +1670,15 @@ impl<T: Clone> From<&[T]> for Rc<[T]> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<&str> for Rc<str> {
+    /// Allocate a reference-counted string slice and copy `v` into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::rc::Rc;
+    /// let shared: Rc<str> = Rc::from("statue");
+    /// assert_eq!("statue", &shared[..]);
+    /// ```
     #[inline]
     fn from(v: &str) -> Rc<str> {
         let rc = Rc::<[u8]>::from(v.as_bytes());
@@ -1669,6 +1688,16 @@ impl From<&str> for Rc<str> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<String> for Rc<str> {
+    /// Allocate a reference-counted string slice and copy `v` into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::rc::Rc;
+    /// let original: String = "statue".to_owned();
+    /// let shared: Rc<str> = Rc::from(original);
+    /// assert_eq!("statue", &shared[..]);
+    /// ```
     #[inline]
     fn from(v: String) -> Rc<str> {
         Rc::from(&v[..])
@@ -1677,6 +1706,16 @@ impl From<String> for Rc<str> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T: ?Sized> From<Box<T>> for Rc<T> {
+    /// Move a boxed object to a new, reference counted, allocation.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::rc::Rc;
+    /// let original: Box<i32> = Box::new(1);
+    /// let shared: Rc<i32> = Rc::from(original);
+    /// assert_eq!(1, *shared);
+    /// ```
     #[inline]
     fn from(v: Box<T>) -> Rc<T> {
         Rc::from_box(v)
@@ -1685,6 +1724,16 @@ impl<T: ?Sized> From<Box<T>> for Rc<T> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T> From<Vec<T>> for Rc<[T]> {
+    /// Allocate a reference-counted slice and move `v`'s items into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::rc::Rc;
+    /// let original: Box<Vec<i32>> = Box::new(vec![1, 2, 3]);
+    /// let shared: Rc<Vec<i32>> = Rc::from(original);
+    /// assert_eq!(vec![1, 2, 3], *shared);
+    /// ```
     #[inline]
     fn from(mut v: Vec<T>) -> Rc<[T]> {
         unsafe {

library/alloc/src/sync.rs

@@ -2285,6 +2285,16 @@ impl<T> From<T> for Arc<T> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T: Clone> From<&[T]> for Arc<[T]> {
+    /// Allocate a reference-counted slice and fill it by cloning `v`'s items.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// let original: &[i32] = &[1, 2, 3];
+    /// let shared: Arc<[i32]> = Arc::from(original);
+    /// assert_eq!(&[1, 2, 3], &shared[..]);
+    /// ```
     #[inline]
     fn from(v: &[T]) -> Arc<[T]> {
         <Self as ArcFromSlice<T>>::from_slice(v)
@@ -2293,6 +2303,15 @@ impl<T: Clone> From<&[T]> for Arc<[T]> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<&str> for Arc<str> {
+    /// Allocate a reference-counted `str` and copy `v` into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// let shared: Arc<str> = Arc::from("eggplant");
+    /// assert_eq!("eggplant", &shared[..]);
+    /// ```
     #[inline]
     fn from(v: &str) -> Arc<str> {
         let arc = Arc::<[u8]>::from(v.as_bytes());
@@ -2302,6 +2321,16 @@ impl From<&str> for Arc<str> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<String> for Arc<str> {
+    /// Allocate a reference-counted `str` and copy `v` into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// let unique: String = "eggplant".to_owned();
+    /// let shared: Arc<str> = Arc::from(unique);
+    /// assert_eq!("eggplant", &shared[..]);
+    /// ```
     #[inline]
     fn from(v: String) -> Arc<str> {
         Arc::from(&v[..])
@@ -2310,6 +2339,16 @@ impl From<String> for Arc<str> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T: ?Sized> From<Box<T>> for Arc<T> {
+    /// Move a boxed object to a new, reference-counted allocation.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// let unique: Box<str> = Box::from("eggplant");
+    /// let shared: Arc<str> = Arc::from(unique);
+    /// assert_eq!("eggplant", &shared[..]);
+    /// ```
     #[inline]
     fn from(v: Box<T>) -> Arc<T> {
         Arc::from_box(v)
@@ -2318,6 +2357,16 @@ impl<T: ?Sized> From<Box<T>> for Arc<T> {
 
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T> From<Vec<T>> for Arc<[T]> {
+    /// Allocate a reference-counted slice and move `v`'s items into it.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// let unique: Vec<i32> = vec![1, 2, 3];
+    /// let shared: Arc<[i32]> = Arc::from(unique);
+    /// assert_eq!(&[1, 2, 3], &shared[..]);
+    /// ```
     #[inline]
     fn from(mut v: Vec<T>) -> Arc<[T]> {
         unsafe {

library/alloc/src/vec/mod.rs

@@ -1385,13 +1385,14 @@ impl<T, A: Allocator> Vec<T, A> {
     /// assert_eq!(vec, [2, 4]);
     /// ```
     ///
-    /// The exact order may be useful for tracking external state, like an index.
+    /// Because the elements are visited exactly once in the original order,
+    /// external state may be used to decide which elements to keep.
     ///
     /// ```
     /// let mut vec = vec![1, 2, 3, 4, 5];
     /// let keep = [false, true, true, false, true];
-    /// let mut i = 0;
-    /// vec.retain(|_| (keep[i], i += 1).0);
+    /// let mut iter = keep.iter();
+    /// vec.retain(|_| *iter.next().unwrap());
     /// assert_eq!(vec, [2, 3, 5]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]

library/alloc/tests/vec.rs

@@ -609,6 +609,17 @@ fn test_move_items_zero_sized() {
     assert_eq!(vec2, [(), (), ()]);
 }
 
+#[test]
+fn test_drain_empty_vec() {
+    let mut vec: Vec<i32> = vec![];
+    let mut vec2: Vec<i32> = vec![];
+    for i in vec.drain(..) {
+        vec2.push(i);
+    }
+    assert!(vec.is_empty());
+    assert!(vec2.is_empty());
+}
+
 #[test]
 fn test_drain_items() {
     let mut vec = vec![1, 2, 3];

src/librustdoc/clean/mod.rs

@@ -2161,18 +2161,20 @@ fn clean_use_statement(
         return Vec::new();
     }
 
-    let (doc_meta_item, please_inline) = import.attrs.lists(sym::doc).get_word_attr(sym::inline);
+    let inline_attr = import.attrs.lists(sym::doc).get_word_attr(sym::inline);
     let pub_underscore = import.vis.node.is_pub() && name == kw::Underscore;
 
-    if pub_underscore && please_inline {
-        rustc_errors::struct_span_err!(
-            cx.tcx.sess,
-            doc_meta_item.unwrap().span(),
-            E0780,
-            "anonymous imports cannot be inlined"
-        )
-        .span_label(import.span, "anonymous import")
-        .emit();
+    if pub_underscore {
+        if let Some(ref inline) = inline_attr {
+            rustc_errors::struct_span_err!(
+                cx.tcx.sess,
+                inline.span(),
+                E0780,
+                "anonymous imports cannot be inlined"
+            )
+            .span_label(import.span, "anonymous import")
+            .emit();
+        }
     }
 
     // We consider inlining the documentation of `pub use` statements, but we
@@ -2205,7 +2207,7 @@ fn clean_use_statement(
         }
         Import::new_glob(resolve_use_source(cx, path), true)
     } else {
-        if !please_inline {
+        if inline_attr.is_none() {
             if let Res::Def(DefKind::Mod, did) = path.res {
                 if !did.is_local() && did.index == CRATE_DEF_INDEX {
                     // if we're `pub use`ing an extern crate root, don't inline it unless we

src/librustdoc/clean/types.rs

@@ -438,7 +438,7 @@ impl AttributesExt for [ast::Attribute] {
 crate trait NestedAttributesExt {
     /// Returns `true` if the attribute list contains a specific `Word`
     fn has_word(self, word: Symbol) -> bool;
-    fn get_word_attr(self, word: Symbol) -> (Option<ast::NestedMetaItem>, bool);
+    fn get_word_attr(self, word: Symbol) -> Option<ast::NestedMetaItem>;
 }
 
 impl<I: Iterator<Item = ast::NestedMetaItem> + IntoIterator<Item = ast::NestedMetaItem>>
@@ -448,11 +448,8 @@ impl<I: Iterator<Item = ast::NestedMetaItem> + IntoIterator<Item = ast::NestedMe
         self.into_iter().any(|attr| attr.is_word() && attr.has_name(word))
     }
 
-    fn get_word_attr(mut self, word: Symbol) -> (Option<ast::NestedMetaItem>, bool) {
-        match self.find(|attr| attr.is_word() && attr.has_name(word)) {
-            Some(a) => (Some(a), true),
-            None => (None, false),
-        }
+    fn get_word_attr(mut self, word: Symbol) -> Option<ast::NestedMetaItem> {
+        self.find(|attr| attr.is_word() && attr.has_name(word))
     }
 }
 

src/test/rustdoc/ensure-src-link.rs

@@ -0,0 +1,6 @@
+#![crate_name = "foo"]
+
+// This test ensures that the [src] link is present on traits items.
+
+// @has foo/trait.Iterator.html '//h3[@id="method.zip"]/a[@class="srclink"]' "[src]"
+pub use std::iter::Iterator;

src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature-2.nll.stderr

@@ -0,0 +1,17 @@
+error[E0311]: the parameter type `T` may not live long enough
+  --> $DIR/missing-lifetimes-in-signature-2.rs:20:5
+   |
+LL | /     foo.bar(move |_| {
+LL | |
+LL | |         t.test();
+LL | |     });
+   | |______^
+   |
+note: the parameter type `T` must be valid for the anonymous lifetime #2 defined on the function body at 19:1...
+  --> $DIR/missing-lifetimes-in-signature-2.rs:19:1
+   |
+LL | fn func<T: Test>(foo: &Foo, t: T) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature-2.rs

@@ -0,0 +1,26 @@
+// Regression test for #81650
+
+struct Foo<'a> {
+    x: &'a mut &'a i32,
+}
+
+impl<'a> Foo<'a> {
+    fn bar<F, T>(&self, f: F)
+    where
+        F: FnOnce(&Foo<'a>) -> T,
+        F: 'a,
+    {}
+}
+
+trait Test {
+    fn test(&self);
+}
+
+fn func<T: Test>(foo: &Foo, t: T) {
+    foo.bar(move |_| {
+    //~^ ERROR the parameter type `T` may not live long enough
+        t.test();
+    });
+}
+
+fn main() {}

src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature-2.stderr

@@ -0,0 +1,21 @@
+error[E0311]: the parameter type `T` may not live long enough
+  --> $DIR/missing-lifetimes-in-signature-2.rs:20:9
+   |
+LL | fn func<T: Test>(foo: &Foo, t: T) {
+   |         -- help: consider adding an explicit lifetime bound...: `T: 'a +`
+LL |     foo.bar(move |_| {
+   |         ^^^
+   |
+note: the parameter type `T` must be valid for the anonymous lifetime #2 defined on the function body at 19:1...
+  --> $DIR/missing-lifetimes-in-signature-2.rs:19:1
+   |
+LL | fn func<T: Test>(foo: &Foo, t: T) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: ...so that the type `[closure@$DIR/missing-lifetimes-in-signature-2.rs:20:13: 23:6]` will meet its required lifetime bounds
+  --> $DIR/missing-lifetimes-in-signature-2.rs:20:9
+   |
+LL |     foo.bar(move |_| {
+   |         ^^^
+
+error: aborting due to previous error
+

src/test/ui/traits/trait-alias-ambiguous.stderr → src/test/ui/traits/alias/ambiguous.stderr

@@ -1,16 +1,16 @@
 error[E0034]: multiple applicable items in scope
-  --> $DIR/trait-alias-ambiguous.rs:21:7
+  --> $DIR/ambiguous.rs:21:7
    |
 LL |     t.foo();
    |       ^^^ multiple `foo` found
    |
 note: candidate #1 is defined in an impl of the trait `A` for the type `u8`
-  --> $DIR/trait-alias-ambiguous.rs:8:9
+  --> $DIR/ambiguous.rs:8:9
    |
 LL |         fn foo(&self) {}
    |         ^^^^^^^^^^^^^
 note: candidate #2 is defined in an impl of the trait `B` for the type `u8`
-  --> $DIR/trait-alias-ambiguous.rs:11:9
+  --> $DIR/ambiguous.rs:11:9
    |
 LL |         fn foo(&self) {}
    |         ^^^^^^^^^^^^^