fix: arithmetic expansions

grammar.js

@@ -562,7 +562,7 @@ module.exports = grammar({
       $.brace_expression,
     ),
 
-    arithmetic_expansion: $ => seq('$((', $._arithmetic_expression, '))'),
+    arithmetic_expansion: $ => seq(choice('$((', '(('), commaSep1($._arithmetic_expression), '))'),
 
     brace_expression: $ => seq(
       alias($._brace_start, '{'),
@@ -583,10 +583,12 @@ module.exports = grammar({
 
     _arithmetic_literal: $ => prec(1, choice(
       $.number,
+      $.test_operator,
       $.subscript,
       $.simple_expansion,
       $.expansion,
       $._simple_variable_name,
+      $.variable_name,
     )),
 
     _arithmetic_binary_expression: $ => prec.left(2, choice(
@@ -619,12 +621,12 @@ module.exports = grammar({
     ),
 
     _arithmetic_unary_expression: $ => choice(
-      prec(1, seq(
+      prec(3, seq(
         token(prec(1, choice('-', '+', '~', '++', '--'))),
         $._arithmetic_expression,
       )),
-      prec.right(1, seq(
+      prec.right(3, seq(
-        choice('!', $.test_operator),
+        '!',
         $._arithmetic_expression,
       )),
     ),

test/corpus/commands.txt

@@ -469,15 +469,13 @@ ${array[((number+1))]}
       (expansion
         (subscript
           (variable_name)
-          (parenthesized_expression
+          (arithmetic_expansion (binary_expression (simple_expansion (variable_name)) (number)))))))
-            (parenthesized_expression
-              (concatenation (simple_expansion (variable_name)) (word))))))))
   (command
     (command_name
       (expansion
         (subscript
           (variable_name)
-          (parenthesized_expression (parenthesized_expression (word))))))))
+          (arithmetic_expansion (binary_expression (variable_name) (number))))))))
 
 ==========================================
 Bare $

test/corpus/literals.txt

@@ -843,6 +843,11 @@ Arithmetic expansions
 echo $((1 + 2 - 3 * 4 / 5))
 a=$((6 % 7 ** 8 << 9 >> 10 & 11 | 12 ^ 13))
 $(((${1:-${SECONDS}} % 12) + 144))
+((foo=0))
+echo $((bar=1))
+echo $((-1, 1))
+echo $((! -a || ~ +b || ++c || --d))
+echo $((foo-- || bar++))
 
 --------------------------------------------------------------------------------
 
@@ -889,7 +894,52 @@ $(((${1:-${SECONDS}} % 12) + 144))
                 (expansion
                   (variable_name)))
               (number)))
-          (number))))))
+          (number)))))
+  (command
+    (command_name
+      (arithmetic_expansion
+        (binary_expression
+          (variable_name)
+          (number)))))
+  (command
+    (command_name
+      (word))
+    (arithmetic_expansion
+      (binary_expression
+        (variable_name)
+        (number))))
+  (command
+    (command_name
+      (word))
+    (arithmetic_expansion
+      (unary_expression
+        (number))
+      (number)))
+  (command
+    (command_name
+      (word))
+    (arithmetic_expansion
+      (binary_expression
+        (binary_expression
+          (binary_expression
+            (unary_expression
+              (test_operator))
+            (unary_expression
+              (unary_expression
+                (variable_name))))
+          (unary_expression
+            (variable_name)))
+        (unary_expression
+          (variable_name)))))
+  (command
+    (command_name
+      (word))
+    (arithmetic_expansion
+      (postfix_expression
+        (binary_expression
+          (postfix_expression
+            (variable_name))
+          (variable_name))))))
 
 ================================================================================
 Concatenation with double backticks

test/corpus/statements.txt

@@ -393,11 +393,13 @@ done )
         (simple_expansion
           (variable_name)))
       (if_statement
-        (test_command
+        (command
+          (command_name
+            (arithmetic_expansion
               (binary_expression
                 (simple_expansion
                   (variable_name))
-            (regex)))
+                (number)))))
         (command
           (command_name
             (word))))))
@@ -421,8 +423,12 @@ done )
           (command_substitution
             (redirected_statement
               (list
-                (test_command
+                (command
-                  (word))
+                  (command_name
+                    (arithmetic_expansion
+                      (binary_expression
+                        (variable_name)
+                        (number)))))
                 (command
                   (command_name
                     (word))
@@ -470,8 +476,12 @@ done )
             (command_substitution
               (redirected_statement
                 (list
-                  (test_command
+                  (command
-                    (word))
+                    (command_name
+                      (arithmetic_expansion
+                        (binary_expression
+                          (variable_name)
+                          (number)))))
                   (command
                     (command_name
                       (word))
@@ -935,13 +945,15 @@ fi
 
 (program
   (if_statement
-    (test_command
+    (command
+      (command_name
+        (arithmetic_expansion
           (ternary_expression
             (binary_expression
               (number)
               (number))
             (number)
-        (number)))
+            (number)))))
     (command
       (command_name
         (word))