Rollup merge of #144200 - estebank:dont-point-at-closure, r=lcnr

Tweak output for non-`Clone` values moved into closures

When we encounter a non-`Clone` value being moved into a closure, try to find the corresponding type of the binding being moved, if it is a `let`-binding or a function parameter. If any of those cases, we point at them with the note explaining that the type is not `Copy`, instead of giving that label to the place where it is captured. When it is a `let`-binding with no explicit type, we point at the initializer (if it fits in a single line).

```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
  --> f111.rs:14:25
   |
13 | fn do_stuff(foo: Option<Foo>) {
   |             ---  ----------- move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
   |             |
   |             captured outer variable
14 |     require_fn_trait(|| async {
   |                      -- ^^^^^ `foo` is moved here
   |                      |
   |                      captured by this `Fn` closure
15 |         if foo.map_or(false, |f| f.foo()) {
   |            --- variable moved due to use in coroutine
```

instead of

```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
  --> f111.rs:14:25
   |
13 | fn do_stuff(foo: Option<Foo>) {
   |             --- captured outer variable
14 |     require_fn_trait(|| async {
   |                      -- ^^^^^ `foo` is moved here
   |                      |
   |                      captured by this `Fn` closure
15 |         if foo.map_or(false, |f| f.foo()) {
   |            ---
   |            |
   |            variable moved due to use in coroutine
   |            move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
```

11 files changed, 65 insertions, 48 deletions

diff --git a/tests/ui/async-await/async-closures/closure-shim-borrowck-error.stderr b/tests/ui/async-await/async-closures/closure-shim-borrowck-error.stderr
index 03fa220b0bf..3fe1431fda7 100644
--- a/tests/ui/async-await/async-closures/closure-shim-borrowck-error.stderr
+++ b/tests/ui/async-await/async-closures/closure-shim-borrowck-error.stderr
@@ -1,14 +1,13 @@
 error[E0507]: cannot move out of `x` which is behind a mutable reference
   --> $DIR/closure-shim-borrowck-error.rs:11:18
    |
+LL | fn hello(x: Ty) {
+   |             -- move occurs because `x` has type `Ty`, which does not implement the `Copy` trait
 LL |     needs_fn_mut(async || {
    |                  ^^^^^^^^ `x` is moved here
 LL |
 LL |         x.hello();
-   |         -
-   |         |
-   |         variable moved due to use in coroutine
-   |         move occurs because `x` has type `Ty`, which does not implement the `Copy` trait
+   |         - variable moved due to use in coroutine
    |
 note: if `Ty` implemented `Clone`, you could clone the value
   --> $DIR/closure-shim-borrowck-error.rs:17:1
diff --git a/tests/ui/async-await/async-closures/move-out-of-ref.stderr b/tests/ui/async-await/async-closures/move-out-of-ref.stderr
index 8a63515a8a9..d443dc9d483 100644
--- a/tests/ui/async-await/async-closures/move-out-of-ref.stderr
+++ b/tests/ui/async-await/async-closures/move-out-of-ref.stderr
@@ -1,8 +1,11 @@
 error[E0507]: cannot move out of `*x` which is behind a shared reference
   --> $DIR/move-out-of-ref.rs:9:9
    |
+LL | fn hello(x: &Ty) {
+   |             --- move occurs because `*x` has type `Ty`, which does not implement the `Copy` trait
+LL |     let c = async || {
 LL |         *x;
-   |         ^^ move occurs because `*x` has type `Ty`, which does not implement the `Copy` trait
+   |         ^^ `*x` is moved here
    |
 note: if `Ty` implemented `Clone`, you could clone the value
   --> $DIR/move-out-of-ref.rs:5:1
diff --git a/tests/ui/borrowck/borrowck-in-static.stderr b/tests/ui/borrowck/borrowck-in-static.stderr
index 745b02ae21b..9bcf64dd62e 100644
--- a/tests/ui/borrowck/borrowck-in-static.stderr
+++ b/tests/ui/borrowck/borrowck-in-static.stderr
@@ -2,9 +2,11 @@ error[E0507]: cannot move out of `x`, a captured variable in an `Fn` closure
   --> $DIR/borrowck-in-static.rs:5:17
    |
 LL |     let x = Box::new(0);
-   |         - captured outer variable
+   |         -   ----------- move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     Box::new(|| x)
-   |              -- ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |              -- ^ `x` is moved here
    |              |
    |              captured by this `Fn` closure
    |
diff --git a/tests/ui/borrowck/borrowck-move-by-capture.stderr b/tests/ui/borrowck/borrowck-move-by-capture.stderr
index 58d5e90e990..732af1593d6 100644
--- a/tests/ui/borrowck/borrowck-move-by-capture.stderr
+++ b/tests/ui/borrowck/borrowck-move-by-capture.stderr
@@ -2,14 +2,14 @@ error[E0507]: cannot move out of `bar`, a captured variable in an `FnMut` closur
   --> $DIR/borrowck-move-by-capture.rs:9:29
    |
 LL |     let bar: Box<_> = Box::new(3);
-   |         --- captured outer variable
+   |         ---  ------ move occurs because `bar` has type `Box<isize>`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     let _g = to_fn_mut(|| {
    |                        -- captured by this `FnMut` closure
 LL |         let _h = to_fn_once(move || -> isize { *bar });
-   |                             ^^^^^^^^^^^^^^^^   ----
-   |                             |                  |
-   |                             |                  variable moved due to use in closure
-   |                             |                  move occurs because `bar` has type `Box<isize>`, which does not implement the `Copy` trait
+   |                             ^^^^^^^^^^^^^^^^   ---- variable moved due to use in closure
+   |                             |
    |                             `bar` is moved here
    |
 help: consider cloning the value before moving it into the closure
diff --git a/tests/ui/borrowck/issue-103624.stderr b/tests/ui/borrowck/issue-103624.stderr
index 603055beadc..af65deb16dc 100644
--- a/tests/ui/borrowck/issue-103624.stderr
+++ b/tests/ui/borrowck/issue-103624.stderr
@@ -2,13 +2,16 @@ error[E0507]: cannot move out of `self.b`, as `self` is a captured variable in a
   --> $DIR/issue-103624.rs:16:13
    |
 LL |     async fn foo(&self) {
-   |                  ----- captured outer variable
+   |                  -----
+   |                  |
+   |                  captured outer variable
+   |                  move occurs because `self.b` has type `StructB`, which does not implement the `Copy` trait
 LL |         let bar = self.b.bar().await;
 LL |         spawn_blocking(move || {
    |                        ------- captured by this `Fn` closure
 LL |
 LL |             self.b;
-   |             ^^^^^^ move occurs because `self.b` has type `StructB`, which does not implement the `Copy` trait
+   |             ^^^^^^ `self.b` is moved here
    |
 note: if `StructB` implemented `Clone`, you could clone the value
   --> $DIR/issue-103624.rs:23:1
diff --git a/tests/ui/issues/issue-4335.stderr b/tests/ui/issues/issue-4335.stderr
index 14b5cfa9f9a..42ac6322564 100644
--- a/tests/ui/issues/issue-4335.stderr
+++ b/tests/ui/issues/issue-4335.stderr
@@ -2,9 +2,11 @@ error[E0507]: cannot move out of `*v`, as `v` is a captured variable in an `FnMu
   --> $DIR/issue-4335.rs:6:20
    |
 LL | fn f<'r, T>(v: &'r T) -> Box<dyn FnMut() -> T + 'r> {
-   |             - captured outer variable
+   |             -  ----- move occurs because `*v` has type `T`, which does not implement the `Copy` trait
+   |             |
+   |             captured outer variable
 LL |     id(Box::new(|| *v))
-   |                 -- ^^ move occurs because `*v` has type `T`, which does not implement the `Copy` trait
+   |                 -- ^^ `*v` is moved here
    |                 |
    |                 captured by this `FnMut` closure
    |
diff --git a/tests/ui/moves/moves-based-on-type-move-out-of-closure-env-issue-1965.stderr b/tests/ui/moves/moves-based-on-type-move-out-of-closure-env-issue-1965.stderr
index 523134a9425..51d0f85c031 100644
--- a/tests/ui/moves/moves-based-on-type-move-out-of-closure-env-issue-1965.stderr
+++ b/tests/ui/moves/moves-based-on-type-move-out-of-closure-env-issue-1965.stderr
@@ -2,9 +2,11 @@ error[E0507]: cannot move out of `i`, a captured variable in an `Fn` closure
   --> $DIR/moves-based-on-type-move-out-of-closure-env-issue-1965.rs:9:28
    |
 LL |     let i = Box::new(3);
-   |         - captured outer variable
+   |         -   ----------- move occurs because `i` has type `Box<usize>`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     let _f = to_fn(|| test(i));
-   |                    --      ^ move occurs because `i` has type `Box<usize>`, which does not implement the `Copy` trait
+   |                    --      ^ `i` is moved here
    |                    |
    |                    captured by this `Fn` closure
    |
diff --git a/tests/ui/nll/issue-52663-span-decl-captured-variable.stderr b/tests/ui/nll/issue-52663-span-decl-captured-variable.stderr
index fbaec8a6008..57546037006 100644
--- a/tests/ui/nll/issue-52663-span-decl-captured-variable.stderr
+++ b/tests/ui/nll/issue-52663-span-decl-captured-variable.stderr
@@ -2,9 +2,11 @@ error[E0507]: cannot move out of `x.0`, as `x` is a captured variable in an `Fn`
   --> $DIR/issue-52663-span-decl-captured-variable.rs:8:26
    |
 LL |        let x = (vec![22], vec![44]);
-   |            - captured outer variable
+   |            -   -------------------- move occurs because `x.0` has type `Vec<i32>`, which does not implement the `Copy` trait
+   |            |
+   |            captured outer variable
 LL |        expect_fn(|| drop(x.0));
-   |                  --      ^^^ move occurs because `x.0` has type `Vec<i32>`, which does not implement the `Copy` trait
+   |                  --      ^^^ `x.0` is moved here
    |                  |
    |                  captured by this `Fn` closure
    |
diff --git a/tests/ui/suggestions/option-content-move2.stderr b/tests/ui/suggestions/option-content-move2.stderr
index be97cba17b9..436441d6f1b 100644
--- a/tests/ui/suggestions/option-content-move2.stderr
+++ b/tests/ui/suggestions/option-content-move2.stderr
@@ -2,7 +2,9 @@ error[E0507]: cannot move out of `var`, a captured variable in an `FnMut` closur
   --> $DIR/option-content-move2.rs:11:9
    |
 LL |     let mut var = None;
-   |         ------- captured outer variable
+   |         -------   ---- move occurs because `var` has type `Option<NotCopyable>`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     func(|| {
    |          -- captured by this `FnMut` closure
 LL |         // Shouldn't suggest `move ||.as_ref()` here
@@ -10,16 +12,15 @@ LL |         move || {
    |         ^^^^^^^ `var` is moved here
 LL |
 LL |             var = Some(NotCopyable);
-   |             ---
-   |             |
-   |             variable moved due to use in closure
-   |             move occurs because `var` has type `Option<NotCopyable>`, which does not implement the `Copy` trait
+   |             --- variable moved due to use in closure
 
 error[E0507]: cannot move out of `var`, a captured variable in an `FnMut` closure
   --> $DIR/option-content-move2.rs:21:9
    |
 LL |     let mut var = None;
-   |         ------- captured outer variable
+   |         -------   ---- move occurs because `var` has type `Option<NotCopyableButCloneable>`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     func(|| {
    |          -- captured by this `FnMut` closure
 LL |         // Shouldn't suggest `move ||.as_ref()` nor to `clone()` here
@@ -27,10 +28,7 @@ LL |         move || {
    |         ^^^^^^^ `var` is moved here
 LL |
 LL |             var = Some(NotCopyableButCloneable);
-   |             ---
-   |             |
-   |             variable moved due to use in closure
-   |             move occurs because `var` has type `Option<NotCopyableButCloneable>`, which does not implement the `Copy` trait
+   |             --- variable moved due to use in closure
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/suggestions/option-content-move3.stderr b/tests/ui/suggestions/option-content-move3.stderr
index faaf8a9df9d..68c52352a65 100644
--- a/tests/ui/suggestions/option-content-move3.stderr
+++ b/tests/ui/suggestions/option-content-move3.stderr
@@ -26,17 +26,16 @@ error[E0507]: cannot move out of `var`, a captured variable in an `FnMut` closur
   --> $DIR/option-content-move3.rs:12:9
    |
 LL |     let var = NotCopyable;
-   |         --- captured outer variable
+   |         ---   ----------- move occurs because `var` has type `NotCopyable`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     func(|| {
    |          -- captured by this `FnMut` closure
 LL |         // Shouldn't suggest `move ||.as_ref()` here
 LL |         move || {
    |         ^^^^^^^ `var` is moved here
 LL |             let x = var;
-   |                     ---
-   |                     |
-   |                     variable moved due to use in closure
-   |                     move occurs because `var` has type `NotCopyable`, which does not implement the `Copy` trait
+   |                     --- variable moved due to use in closure
    |
 note: if `NotCopyable` implemented `Clone`, you could clone the value
   --> $DIR/option-content-move3.rs:2:1
@@ -67,17 +66,16 @@ error[E0507]: cannot move out of `var`, a captured variable in an `FnMut` closur
   --> $DIR/option-content-move3.rs:23:9
    |
 LL |     let var = NotCopyableButCloneable;
-   |         --- captured outer variable
+   |         ---   ----------------------- move occurs because `var` has type `NotCopyableButCloneable`, which does not implement the `Copy` trait
+   |         |
+   |         captured outer variable
 LL |     func(|| {
    |          -- captured by this `FnMut` closure
 LL |         // Shouldn't suggest `move ||.as_ref()` here
 LL |         move || {
    |         ^^^^^^^ `var` is moved here
 LL |             let x = var;
-   |                     ---
-   |                     |
-   |                     variable moved due to use in closure
-   |                     move occurs because `var` has type `NotCopyableButCloneable`, which does not implement the `Copy` trait
+   |                     --- variable moved due to use in closure
    |
 help: consider cloning the value before moving it into the closure
    |
diff --git a/tests/ui/unboxed-closures/unboxed-closure-illegal-move.stderr b/tests/ui/unboxed-closures/unboxed-closure-illegal-move.stderr
index cf4391311d0..8d9a61cb681 100644
--- a/tests/ui/unboxed-closures/unboxed-closure-illegal-move.stderr
+++ b/tests/ui/unboxed-closures/unboxed-closure-illegal-move.stderr
@@ -2,9 +2,11 @@ error[E0507]: cannot move out of `x`, a captured variable in an `Fn` closure
   --> $DIR/unboxed-closure-illegal-move.rs:15:31
    |
 LL |         let x = Box::new(0);
-   |             - captured outer variable
+   |             -   ----------- move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |             |
+   |             captured outer variable
 LL |         let f = to_fn(|| drop(x));
-   |                       --      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |                       --      ^ `x` is moved here
    |                       |
    |                       captured by this `Fn` closure
    |
@@ -17,9 +19,11 @@ error[E0507]: cannot move out of `x`, a captured variable in an `FnMut` closure
   --> $DIR/unboxed-closure-illegal-move.rs:19:35
    |
 LL |         let x = Box::new(0);
-   |             - captured outer variable
+   |             -   ----------- move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |             |
+   |             captured outer variable
 LL |         let f = to_fn_mut(|| drop(x));
-   |                           --      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |                           --      ^ `x` is moved here
    |                           |
    |                           captured by this `FnMut` closure
    |
@@ -32,9 +36,11 @@ error[E0507]: cannot move out of `x`, a captured variable in an `Fn` closure
   --> $DIR/unboxed-closure-illegal-move.rs:28:36
    |
 LL |         let x = Box::new(0);
-   |             - captured outer variable
+   |             -   ----------- move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |             |
+   |             captured outer variable
 LL |         let f = to_fn(move || drop(x));
-   |                       -------      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |                       -------      ^ `x` is moved here
    |                       |
    |                       captured by this `Fn` closure
 
@@ -42,9 +48,11 @@ error[E0507]: cannot move out of `x`, a captured variable in an `FnMut` closure
   --> $DIR/unboxed-closure-illegal-move.rs:32:40
    |
 LL |         let x = Box::new(0);
-   |             - captured outer variable
+   |             -   ----------- move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |             |
+   |             captured outer variable
 LL |         let f = to_fn_mut(move || drop(x));
-   |                           -------      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
+   |                           -------      ^ `x` is moved here
    |                           |
    |                           captured by this `FnMut` closure