Auto merge of rust-lang#112549 - jieyouxu:fix-tests-for-unit-bindings, r=Nilstrieb

Adjust UI tests for `unit_bindings` lint

- Explicitly annotate `let x: () = expr;` where `x` has unit type, or remove the unit binding to leave only `expr;` instead.
- Use `let () = init;` or `let pat = ();` where appropriate.
- Fix disjoint-capture-in-same-closure test which wasn't actually testing a closure: `tests/ui/closures/2229_closure_analysis/run_pass/disjoint-capture-in-same-closure.rs`.

Note that unfortunately there's *a lot* of UI tests, there are a couple of places where I may have left something like `let (): ()` (this is not needed but is left over from an ealier version of the lint) which is bad style.

This PR is to help with the `unit_bindings` lint at rust-lang#112380.

Author: bors

tests/ui/assign-assign.rs

@@ -6,7 +6,7 @@ fn test_assign() {
     let y: () = x = 10;
     assert_eq!(x, 10);
     assert_eq!(y, ());
-    let mut z = x = 11;
+    let mut z: () = x = 11;
     assert_eq!(x, 11);
     assert_eq!(z, ());
     z = x = 12;
@@ -19,7 +19,7 @@ fn test_assign_op() {
     let y: () = x += 10;
     assert_eq!(x, 10);
     assert_eq!(y, ());
-    let mut z = x += 11;
+    let mut z: () = x += 11;
     assert_eq!(x, 21);
     assert_eq!(z, ());
     z = x += 12;

tests/ui/associated-type-bounds/dyn-impl-trait-type.rs

@@ -59,8 +59,8 @@ fn def_et4() -> Et4 {
 pub fn use_et4() { assert_forall_tr2(def_et4().mk()); }
 
 fn main() {
-    let _ = use_et1();
-    let _ = use_et2();
-    let _ = use_et3();
-    let _ = use_et4();
+    use_et1();
+    use_et2();
+    use_et3();
+    use_et4();
 }

tests/ui/associated-type-bounds/dyn-rpit-and-let.rs

@@ -66,8 +66,8 @@ fn def_et4() -> Box<dyn Tr1<As1: for<'a> Tr2<'a>>> {
 pub fn use_et4() { assert_forall_tr2(def_et4().mk()); }
 
 fn main() {
-    let _ = use_et1();
-    let _ = use_et2();
-    let _ = use_et3();
-    let _ = use_et4();
+    use_et1();
+    use_et2();
+    use_et3();
+    use_et4();
 }

tests/ui/associated-type-bounds/rpit.rs

@@ -57,8 +57,8 @@ fn def_et4() -> impl Tr1<As1: for<'a> Tr2<'a>> {
 pub fn use_et4() { assert_forall_tr2(def_et4().mk()); }
 
 fn main() {
-    let _ = use_et1();
-    let _ = use_et2();
-    let _ = use_et3();
-    let _ = use_et4();
+    use_et1();
+    use_et2();
+    use_et3();
+    use_et4();
 }

tests/ui/associated-type-bounds/trait-alias-impl-trait.rs

@@ -89,8 +89,8 @@ pub fn use_et4() {
 }
 
 fn main() {
-    let _ = use_et1();
-    let _ = use_et2();
-    let _ = use_et3();
-    let _ = use_et4();
+    use_et1();
+    use_et2();
+    use_et3();
+    use_et4();
 }

tests/ui/associated-types/normalization-debruijn-3.rs

@@ -6,10 +6,10 @@
 
 use std::future::{Future, Ready};
 async fn read() {
-    let _ = connect(&()).await;
+    connect(&()).await;
 }
 async fn connect<A: ToSocketAddr>(addr: A) {
-    let _ = addr.to_socket_addr().await;
+    addr.to_socket_addr().await;
 }
 pub trait ToSocketAddr {
     type Future: Future<Output = ()>;

tests/ui/async-await/drop-track-field-assign.rs

@@ -21,7 +21,7 @@ impl Agent {
         let mut info = self.info_result.clone();
         info.node = Some("bar".into());
         let element = parse_info(info);
-        let _ = send_element(element).await;
+        send_element(element).await;
     }
 }
 

tests/ui/async-await/field-assign.rs

@@ -21,7 +21,7 @@ impl Agent {
         let mut info = self.info_result.clone();
         info.node = Some("bar".into());
         let element = parse_info(info);
-        let _ = send_element(element).await;
+        send_element(element).await;
     }
 }
 

tests/ui/async-await/issue-64130-4-async-move.no_drop_tracking.stderr

@@ -6,13 +6,13 @@ LL | pub fn foo() -> impl Future + Send {
    |
    = help: the trait `Sync` is not implemented for `(dyn Any + Send + 'static)`
 note: future is not `Send` as this value is used across an await
-  --> $DIR/issue-64130-4-async-move.rs:27:32
+  --> $DIR/issue-64130-4-async-move.rs:27:23
    |
 LL |         match client.status() {
    |               ------ has type `&Client` which is not `Send`
 LL |             200 => {
-LL |                 let _x = get().await;
-   |                                ^^^^^ await occurs here, with `client` maybe used later
+LL |                 get().await;
+   |                       ^^^^^ await occurs here, with `client` maybe used later
 ...
 LL |     }
    |     - `client` is later dropped here

tests/ui/async-await/issue-64130-4-async-move.rs

@@ -24,7 +24,7 @@ pub fn foo() -> impl Future + Send {
     async move {
         match client.status() {
             200 => {
-                let _x = get().await;
+                get().await;
             }
             _ => (),
         }