Suppress redundant error

compiler/rustc_hir/src/hir.rs

@@ -2370,6 +2370,10 @@ impl Expr<'_> {
             // Lang item paths cannot currently be local variables or statics.
             ExprKind::Path(QPath::LangItem(..)) => false,
 
+            // Suppress errors for bad expressions.
+            ExprKind::Err(_guar)
+            | ExprKind::Let(&LetExpr { recovered: ast::Recovered::Yes(_guar), .. }) => true,
+
             // Partially qualified paths in expressions can only legally
             // refer to associated items which are always rvalues.
             ExprKind::Path(QPath::TypeRelative(..))
@@ -2401,8 +2405,7 @@ impl Expr<'_> {
             | ExprKind::Binary(..)
             | ExprKind::Yield(..)
             | ExprKind::Cast(..)
-            | ExprKind::DropTemps(..)
-            | ExprKind::Err(_) => false,
+            | ExprKind::DropTemps(..) => false,
         }
     }
 

tests/ui/destructuring-assignment/bad-let-in-destructure.rs

@@ -10,5 +10,4 @@ fn main() {
   // in the AST, the `let` expression was visited first.
   (let x = 1,) = x;
   //~^ ERROR expected expression, found `let` statement
-  //~| ERROR invalid left-hand side of assignment
 }

tests/ui/destructuring-assignment/bad-let-in-destructure.stderr

@@ -1,19 +1,10 @@
 error: expected expression, found `let` statement
-  --> $DIR/bad-let-in-destructure.rs:10:4
+  --> $DIR/bad-let-in-destructure.rs:11:4
    |
 LL |   (let x = 1,) = x;
    |    ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 
-error[E0070]: invalid left-hand side of assignment
-  --> $DIR/bad-let-in-destructure.rs:10:16
-   |
-LL |   (let x = 1,) = x;
-   |    ---------   ^
-   |    |
-   |    cannot assign to this expression
+error: aborting due to 1 previous error
 
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0070`.