Rollup merge of #139035 - nnethercote:PatKind-Missing, r=oli-obk

Add new `PatKind::Missing` variants

To avoid some ugly uses of `kw::Empty` when handling "missing" patterns, e.g. in bare fn tys. Helps with #137978. Details in the individual commits.

r? ``@oli-obk``

2 files changed, 14 insertions, 15 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index dae0efcbbc4..38c2bf54432 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -779,21 +779,19 @@ impl EarlyLintPass for AnonymousParameters {
         }
         if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind {
             for arg in sig.decl.inputs.iter() {
-                if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
-                    if ident.name == kw::Empty {
-                        let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
+                if let ast::PatKind::Missing = arg.pat.kind {
+                    let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
 
-                        let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
-                            (snip.as_str(), Applicability::MachineApplicable)
-                        } else {
-                            ("<type>", Applicability::HasPlaceholders)
-                        };
-                        cx.emit_span_lint(
-                            ANONYMOUS_PARAMETERS,
-                            arg.pat.span,
-                            BuiltinAnonymousParams { suggestion: (arg.pat.span, appl), ty_snip },
-                        );
-                    }
+                    let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
+                        (snip.as_str(), Applicability::MachineApplicable)
+                    } else {
+                        ("<type>", Applicability::HasPlaceholders)
+                    };
+                    cx.emit_span_lint(
+                        ANONYMOUS_PARAMETERS,
+                        arg.pat.span,
+                        BuiltinAnonymousParams { suggestion: (arg.pat.span, appl), ty_snip },
+                    );
                 }
             }
         }
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index 7b43aac90c7..806bca78f78 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -1201,7 +1201,8 @@ impl EarlyLintPass for UnusedParens {
             // Do not lint on `(..)` as that will result in the other arms being useless.
             Paren(_)
             // The other cases do not contain sub-patterns.
-            | Wild | Never | Rest | Expr(..) | MacCall(..) | Range(..) | Ident(.., None) | Path(..) | Err(_) => {},
+            | Missing | Wild | Never | Rest | Expr(..) | MacCall(..) | Range(..) | Ident(.., None)
+            | Path(..) | Err(_) => {},
             // These are list-like patterns; parens can always be removed.
             TupleStruct(_, _, ps) | Tuple(ps) | Slice(ps) | Or(ps) => for p in ps {
                 self.check_unused_parens_pat(cx, p, false, false, keep_space);