Separate `RemoveLet` span into primary span for `let` and removal
suggestion span for `let `, so that primary span does not include
whitespace.

Fixes: rust-lang#133031

Signed-off-by: Tyrone Wu <[email protected]>

Look at the expression that was parsed when trying to recover from a bad `if` condition to determine what was likely intended by the user beyond "maybe this was meant to be an `else` body".

```
error: expected `{`, found `map`
  --> $DIR/missing-dot-on-if-condition-expression-fixable.rs:4:30
   |
LL |     for _ in [1, 2, 3].iter()map(|x| x) {}
   |                              ^^^ expected `{`
   |
help: you might have meant to write a method call
   |
LL |     for _ in [1, 2, 3].iter().map(|x| x) {}
   |                              +
```

If a macro statement has been parsed after `else`, suggest a missing `if`:

```
error: expected `{`, found `falsy`
  --> $DIR/else-no-if.rs:47:12
   |
LL |     } else falsy! {} {
   |       ---- ^^^^^
   |       |
   |       expected an `if` or a block after this `else`
   |
help: add an `if` if this is the condition of a chained `else if` statement
   |
LL |     } else if falsy! {} {
   |            ++
```

…ngjubilee

ABI checks: add support for some tier3 arches, warn on others.

Followup to
- rust-lang#132842
- rust-lang#132173
- rust-lang#131800

r? ``@workingjubilee``

Increase accuracy of `if` condition misparse suggestion

Fix rust-lang#132656.

Look at the expression that was parsed when trying to recover from a bad `if` condition to determine what was likely intended by the user beyond "maybe this was meant to be an `else` body".

```
error: expected `{`, found `map`
  --> $DIR/missing-dot-on-if-condition-expression-fixable.rs:4:30
   |
LL |     for _ in [1, 2, 3].iter()map(|x| x) {}
   |                              ^^^ expected `{`
   |
help: you might have meant to write a method call
   |
LL |     for _ in [1, 2, 3].iter().map(|x| x) {}
   |                              +
```

If a macro statement has been parsed after `else`, suggest a missing `if`:

```
error: expected `{`, found `falsy`
  --> $DIR/else-no-if.rs:47:12
   |
LL |     } else falsy! {} {
   |       ---- ^^^^^
   |       |
   |       expected an `if` or a block after this `else`
   |
help: add an `if` if this is the condition of a chained `else if` statement
   |
LL |     } else if falsy! {} {
   |            ++
```

…n, r=jieyouxu

Trim whitespace in RemoveLet primary span

Separate `RemoveLet` span into primary span for `let` and removal suggestion span for `let `, so that primary span does not include whitespace.

Fixes: rust-lang#133031

Let chains tests

Filing this as this marks off two of the open issues in rust-lang#132833:

* extending the tests for `move-guard-if-let-chain.rs` and `conflicting_bindings.rs` to have chains with multiple let's (one implementation could for example search for the first `let` and then terminate).
* An instance where a temporary lives shorter than with nested ifs, breaking compilation: rust-lang#103476. This was fixed in the end by the if let rescoping work.

Closes rust-lang#103476

stabilize const_ptr_is_null

FCP passed in rust-lang#74939.

The second commit cleans up const stability around UB checks a bit, now that everything they need (except for `const_eval_select`) is stable.

Fixes rust-lang#74939

alloc: fix `String`'s doc

Just a minor fix for `String` struct.