Recover for PAT = EXPR {}

compiler/rustc_parse/src/errors.rs

@@ -585,14 +585,13 @@ pub(crate) struct MissingInInForLoop {
 
 #[derive(Subdiagnostic)]
 pub(crate) enum MissingInInForLoopSub {
+    // User wrote `for pat of expr {}`
     // Has been misleading, at least in the past (closed Issue #48492), thus maybe-incorrect
-    #[suggestion(
-        parse_use_in_not_of,
-        style = "verbose",
-        applicability = "maybe-incorrect",
-        code = "in"
-    )]
+    #[suggestion(parse_use_in, style = "verbose", applicability = "maybe-incorrect", code = "in")]
     InNotOf(#[primary_span] Span),
+    // User wrote `for pat = expr {}`
+    #[suggestion(parse_use_in, style = "verbose", applicability = "maybe-incorrect", code = "in")]
+    InNotEq(#[primary_span] Span),
     #[suggestion(parse_add_in, style = "verbose", applicability = "maybe-incorrect", code = " in ")]
     AddIn(#[primary_span] Span),
 }

compiler/rustc_parse/src/parser/expr.rs

@@ -3028,6 +3028,8 @@ impl<'a> Parser<'a> {
             let span = self.token.span;
             self.bump();
             (span, errors::MissingInInForLoopSub::InNotOf)
+        } else if self.eat(exp!(Eq)) {
+            (self.prev_token.span, errors::MissingInInForLoopSub::InNotEq)
         } else {
             (self.prev_token.span.between(self.token.span), errors::MissingInInForLoopSub::AddIn)
         };