Auto merge of #116688 - compiler-errors:rustfmt-up, r=WaffleLapkin,Nilstrieb

Format all the let-chains in compiler crates

Since rust-lang/rustfmt#5910 has landed, soon we will have support for formatting let-chains (as soon as rustfmt syncs and beta gets bumped).

This PR applies the changes [from master rustfmt to rust-lang/rust eagerly](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/out.20formatting.20of.20prs/near/374997516), so that the next beta bump does not have to deal with a 200+ file diff and can remain concerned with other things like `cfg(bootstrap)` -- #113637 was a pain to land, for example, because of let-else.

I will also add this commit to the ignore list after it has landed.

The commands that were run -- I'm not great at bash-foo, but this applies rustfmt to every compiler crate, and then reverts the two crates that should probably be formatted out-of-tree.
```
~/rustfmt $ ls -1d ~/rust/compiler/* | xargs -I@ cargo run --bin rustfmt -- `@/src/lib.rs` --config-path ~/rust --edition=2021 # format all of the compiler crates
~/rust $ git checkout HEAD -- compiler/rustc_codegen_{gcc,cranelift} # revert changes to cg-gcc and cg-clif
```

cc `@rust-lang/rustfmt`
r? `@WaffleLapkin` or `@Nilstrieb` who said they may be able to review this purely mechanical PR :>

cc `@Mark-Simulacrum` and `@petrochenkov,` who had some thoughts on the order of operations with big formatting changes in https://github.com/rust-lang/rust/pull/95262#issue-1178993801. I think the situation has changed since then, given that let-chains support exists on master rustfmt now, and I'm fairly confident that this formatting PR should land even if *bootstrap* rustfmt doesn't yet format let-chains in order to lessen the burden of the next beta bump.

1 files changed, 9 insertions, 4 deletions

diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 76659458dad..46683d2d258 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -405,7 +405,9 @@ fn parse_stability(sess: &Session, attr: &Attribute) -> Option<(Symbol, Stabilit
         }
     }
 
-    if let Some(s) = since && s.as_str() == VERSION_PLACEHOLDER {
+    if let Some(s) = since
+        && s.as_str() == VERSION_PLACEHOLDER
+    {
         since = Some(rust_version_symbol());
     }
 
@@ -694,13 +696,16 @@ pub fn eval_condition(
                     !eval_condition(mis[0].meta_item().unwrap(), sess, features, eval)
                 }
                 sym::target => {
-                    if let Some(features) = features && !features.cfg_target_compact {
+                    if let Some(features) = features
+                        && !features.cfg_target_compact
+                    {
                         feature_err(
                             sess,
                             sym::cfg_target_compact,
                             cfg.span,
-                            "compact `cfg(target(..))` is experimental and subject to change"
-                        ).emit();
+                            "compact `cfg(target(..))` is experimental and subject to change",
+                        )
+                        .emit();
                     }
 
                     mis.iter().fold(true, |res, mi| {