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.

compiler/rustc_ast/src/attr/mod.rs

@@ -520,9 +520,7 @@ impl NestedMetaItem {
         I: Iterator<Item = &'a TokenTree>,
     {
         match tokens.peek() {
-            Some(TokenTree::Token(token, _))
-                if let Some(lit) = MetaItemLit::from_token(token) =>
-            {
+            Some(TokenTree::Token(token, _)) if let Some(lit) = MetaItemLit::from_token(token) => {
                 tokens.next();
                 return Some(NestedMetaItem::Lit(lit));
             }

compiler/rustc_ast/src/entry.rs

@@ -21,7 +21,9 @@ pub fn entry_point_type(
     } else if attr::contains_name(attrs, sym::rustc_main) {
         EntryPointType::RustcMainAttr
     } else {
-        if let Some(name) = name && name == sym::main {
+        if let Some(name) = name
+            && name == sym::main
+        {
             if at_root {
                 // This is a top-level function so it can be `main`.
                 EntryPointType::MainNamed

compiler/rustc_ast/src/token.rs

@@ -107,13 +107,11 @@ impl Lit {
     /// Keep this in sync with `Token::can_begin_literal_or_bool` excluding unary negation.
     pub fn from_token(token: &Token) -> Option<Lit> {
         match token.uninterpolate().kind {
-            Ident(name, false) if name.is_bool_lit() => {
-                Some(Lit::new(Bool, name, None))
-            }
+            Ident(name, false) if name.is_bool_lit() => Some(Lit::new(Bool, name, None)),
             Literal(token_lit) => Some(token_lit),
             Interpolated(ref nt)
                 if let NtExpr(expr) | NtLiteral(expr) = &**nt
-                && let ast::ExprKind::Lit(token_lit) = expr.kind =>
+                    && let ast::ExprKind::Lit(token_lit) = expr.kind =>
             {
                 Some(token_lit)
             }
@@ -655,7 +653,9 @@ impl Token {
 
     /// Returns `true` if the token is an interpolated path.
     fn is_path(&self) -> bool {
-        if let Interpolated(nt) = &self.kind && let NtPath(..) = **nt {
+        if let Interpolated(nt) = &self.kind
+            && let NtPath(..) = **nt
+        {
             return true;
         }
 
@@ -677,7 +677,9 @@ impl Token {
 
     /// Is the token an interpolated block (`$b:block`)?
     pub fn is_whole_block(&self) -> bool {
-        if let Interpolated(nt) = &self.kind && let NtBlock(..) = **nt {
+        if let Interpolated(nt) = &self.kind
+            && let NtBlock(..) = **nt
+        {
             return true;
         }
 

compiler/rustc_ast/src/tokenstream.rs

@@ -550,7 +550,9 @@ impl TokenStream {
 
         let stream_iter = stream.0.iter().cloned();
 
-        if let Some(first) = stream.0.first() && Self::try_glue_to_last(vec_mut, first) {
+        if let Some(first) = stream.0.first()
+            && Self::try_glue_to_last(vec_mut, first)
+        {
             // Now skip the first token tree from `stream`.
             vec_mut.extend(stream_iter.skip(1));
         } else {