Keep track of patterns that could have introduced a binding, but didn't

When we recover from a pattern parse error, or a pattern uses `..`, we keep track of that and affect resolution error for missing bindings that could have been provided by that pattern. We differentiate between `..` and parse recovery. We silence resolution errors likely caused by the pattern parse error.

```
error[E0425]: cannot find value `title` in this scope
  --> $DIR/struct-pattern-with-missing-fields-resolve-error.rs:19:30
   |
LL |         println!("[{}]({})", title, url);
   |                              ^^^^^ not found in this scope
   |
note: `Website` has a field `title` which could have been included in this pattern, but it wasn't
  --> $DIR/struct-pattern-with-missing-fields-resolve-error.rs:17:12
   |
LL | / struct Website {
LL | |     url: String,
LL | |     title: Option<String> ,
   | |     ----- defined here
LL | | }
   | |_-
...
LL |       if let Website { url, .. } = website {
   |              ^^^^^^^^^^^^^^^^^^^ this pattern doesn't include `title`, which is available in `Website`
```

Fix #74863.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 4cda887a02b..255be721525 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -1371,10 +1371,10 @@ impl<'a> Parser<'a> {
         self.bump();
         let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
             e.span_label(path.span, "while parsing the fields for this pattern");
-            e.emit();
+            let guar = e.emit();
             self.recover_stmt();
             // When recovering, pretend we had `Foo { .. }`, to avoid cascading errors.
-            (ThinVec::new(), PatFieldsRest::Rest)
+            (ThinVec::new(), PatFieldsRest::Recovered(guar))
         });
         self.bump();
         Ok(PatKind::Struct(qself, path, fields, etc))