Suggest `;` or assignment to drop borrows in tail exprs

Address the diagnostics part of #70844.

```
error[E0597]: `counter` does not live long enough
  --> $DIR/issue-54556-niconii.rs:22:20
   |
LL |     if let Ok(_) = counter.lock() { }
   |                    ^^^^^^^-------
   |                    |
   |                    borrowed value does not live long enough
   |                    a temporary with access to the borrow is created here ...
...
LL | }
   | -
   | |
   | `counter` dropped here while still borrowed
   | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result<MutexGuard<'_>, ()>`
   |
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
   |
LL |     if let Ok(_) = counter.lock() { };
   |                                      ^
```

7 files changed, 78 insertions, 16 deletions

diff --git a/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr b/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr
index 8412cbdc54b..2dca92e2be1 100644
--- a/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr
+++ b/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr
@@ -13,7 +13,10 @@ LL |
 LL |     ;
    |     - ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D`
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |             D("other").next(&_thing1);
+   |                                      ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/nll/issue-54556-niconii.stderr b/src/test/ui/nll/issue-54556-niconii.stderr
index 40cd04de5ec..b4791fd22b4 100644
--- a/src/test/ui/nll/issue-54556-niconii.stderr
+++ b/src/test/ui/nll/issue-54556-niconii.stderr
@@ -13,7 +13,10 @@ LL | }
    | `counter` dropped here while still borrowed
    | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result<MutexGuard<'_>, ()>`
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     if let Ok(_) = counter.lock() { };
+   |                                      ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/nll/issue-54556-stephaneyfx.stderr b/src/test/ui/nll/issue-54556-stephaneyfx.stderr
index 0bf76485eef..77065f0b8d2 100644
--- a/src/test/ui/nll/issue-54556-stephaneyfx.stderr
+++ b/src/test/ui/nll/issue-54556-stephaneyfx.stderr
@@ -12,7 +12,12 @@ LL | }
    | `stmt` dropped here while still borrowed
    | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::iter::Map<Rows<'_>, [closure@$DIR/issue-54556-stephaneyfx.rs:28:14: 28:23]>`
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |     let x = rows.map(|row| row).next(); x
+   |     ^^^^^^^                           ^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr b/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr
index 513dca7950a..047fdbc9148 100644
--- a/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr
+++ b/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr
@@ -12,7 +12,10 @@ LL |
 LL |     ;
    |     - ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D`
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |         D(&_thing1).end();
+   |                          ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr b/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr
index 52d0870b78f..85920a8e739 100644
--- a/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr
+++ b/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr
@@ -8,7 +8,10 @@ LL |     {              let mut _t1 = D(Box::new("t1")); D(&_t1).end()    } ; //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     {              let mut _t1 = D(Box::new("t1")); D(&_t1).end();    } ; // suggest `;`
+   |                                                                  ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:13:55
@@ -20,7 +23,10 @@ LL |     {            { let mut _t1 = D(Box::new("t1")); D(&_t1).end() }  } ; //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     {            { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); }  } ; // suggest `;`
+   |                                                                  ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:16:55
@@ -32,7 +38,10 @@ LL |     {            { let mut _t1 = D(Box::new("t1")); D(&_t1).end() }; }   //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     {            { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); }; }   // suggest `;`
+   |                                                                  ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:19:55
@@ -44,7 +53,10 @@ LL |     let _ =      { let mut _t1 = D(Box::new("t1")); D(&_t1).end()    } ; //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     let _ =      { let mut _t1 = D(Box::new("t1")); D(&_t1).end();    } ; // suggest `;`
+   |                                                                  ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:22:55
@@ -56,7 +68,10 @@ LL |     let _u =     { let mut _t1 = D(Box::new("t1")); D(&_t1).unit()   } ; //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL |     let _u =     { let mut _t1 = D(Box::new("t1")); D(&_t1).unit();   } ; // suggest `;`
+   |                                                                   ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:25:55
@@ -68,7 +83,12 @@ LL |     let _x =     { let mut _t1 = D(Box::new("t1")); D(&_t1).end()    } ; //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |     let _x =     { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x    } ; // `let x = ...; x`
+   |                                                     ^^^^^^^              ^^^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:30:55
@@ -80,7 +100,12 @@ LL |     _y =         { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } ; // `l
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |     _y =         { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x } ; // `let x = ...; x`
+   |                                                     ^^^^^^^              ^^^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:37:55
@@ -93,7 +118,10 @@ LL | fn f_local_ref() { let mut _t1 = D(Box::new("t1")); D(&_t1).unit()   }  //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped.
+help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
+   |
+LL | fn f_local_ref() { let mut _t1 = D(Box::new("t1")); D(&_t1).unit();   }  // suggest `;`
+   |                                                                   ^
 
 error[E0597]: `_t1` does not live long enough
   --> $DIR/issue-54556-used-vs-unused-tails.rs:40:55
@@ -106,7 +134,12 @@ LL | fn f() -> String { let mut _t1 = D(Box::new("t1")); D(&_t1).end()   }   //
    |                                                     | borrowed value does not live long enough
    |                                                     a temporary with access to the borrow is created here ...
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL | fn f() -> String { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x   }   // `let x = ...; x`
+   |                                                     ^^^^^^^              ^^^
 
 error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/span/destructor-restrictions.stderr b/src/test/ui/span/destructor-restrictions.stderr
index a3c6cfb6ae4..b5cd29f99c6 100644
--- a/src/test/ui/span/destructor-restrictions.stderr
+++ b/src/test/ui/span/destructor-restrictions.stderr
@@ -11,7 +11,12 @@ LL |     };
    |     |
    |     `*a` dropped here while still borrowed
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |         let x = *a.borrow() + 1; x
+   |         ^^^^^^^                ^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
index 46969458145..46702d364a8 100644
--- a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
+++ b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
@@ -12,7 +12,12 @@ LL | }
    | `y` dropped here while still borrowed
    | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::cell::Ref<'_, std::string::String>`
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |     let x = y.borrow().clone(); x
+   |     ^^^^^^^                   ^^^
 
 error[E0597]: `y` does not live long enough
   --> $DIR/issue-23338-locals-die-before-temps-of-body.rs:17:9
@@ -27,7 +32,12 @@ LL |     };
    |     |
    |     `y` dropped here while still borrowed
    |
-   = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
+   = note: the temporary is part of an expression at the end of a block;
+           consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
+help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
+   |
+LL |         let x = y.borrow().clone(); x
+   |         ^^^^^^^                   ^^^
 
 error: aborting due to 2 previous errors