support pattern in as_aliasing rule

Author: aspeddro

grammar.js

@@ -675,7 +675,7 @@ module.exports = grammar({
 
     as_aliasing: $ => prec.left(seq(
       'as',
-      $.value_identifier,
+      $._pattern,
       optional($.type_annotation)
     )),
 

test/corpus/expressions.txt

@@ -428,8 +428,8 @@ switch foo {
           (variant_identifier)
           (formal_parameters
             (value_identifier)
-            (as_aliasing (value_identifier))
-            (type_annotation (type_identifier))
+            (as_aliasing (value_identifier)
+            (type_annotation (type_identifier)))
             (record_pattern
               (value_identifier)
               (value_identifier))))
@@ -465,8 +465,8 @@ switch foo {
           (polyvar_identifier)
           (formal_parameters
             (value_identifier)
-            (as_aliasing (value_identifier))
-            (type_annotation (type_identifier))
+            (as_aliasing (value_identifier)
+            (type_annotation (type_identifier)))
             (number)))
         (as_aliasing (value_identifier))
         (expression_statement (number)))

test/corpus/functions.txt

@@ -128,6 +128,7 @@ Parameter aliasing
 ===================================================
 
 (~xTheGreat as x: int=3) => 5
+(~p as (x, _)) => x
 
 ---
 
@@ -138,10 +139,22 @@ Parameter aliasing
         (parameter
           (labeled_parameter
             (value_identifier)
-            (as_aliasing (value_identifier))
-            (type_annotation (type_identifier))
+            (as_aliasing (value_identifier)
+            (type_annotation (type_identifier)))
             (number))))
-      (number))))
+      (number)))
+  
+  (expression_statement
+    (function
+      (formal_parameters
+        (parameter
+          (labeled_parameter
+            (value_identifier)
+            (as_aliasing
+              (tuple_pattern
+                (tuple_item_pattern (value_identifier))
+                (tuple_item_pattern (value_identifier)))))))
+      (value_identifier))))
 
 ===================================================
 Record pattern