'_' isn't an integer and octal, hex, and binary values are

grammar.js

@@ -571,7 +571,12 @@ module.exports = grammar({
     /* Literals */
     string: ($) => /\"(?:\\[efnrt\"\\]|[^\"])*\"/,
     float: ($) => /-?[0-9_]+\.[0-9_]+/,
-    integer: ($) => /-?[0-9_]+/,
+    integer: ($) =>
+      seq(optional("-"), choice($._hex, $._decimal, $._octal, $._binary)),
+    _hex: ($) => /0[xX][0-9a-fA-F_]+/,
+    _decimal: ($) => /[0-9][0-9_]*/,
+    _octal: ($) => /0[oO][0-7_]+/,
+    _binary: ($) => /0[bB][0-1_]+/,
     _bit_string_segment_option_unit: ($) =>
       seq("unit", "(", alias($.integer, $.bit_string_segment_option_unit), ")"),
     _bit_string_segment_option_literal: ($) =>

src/grammar.json

@@ -3957,8 +3957,58 @@
       "value": "-?[0-9_]+\\.[0-9_]+"
     },
     "integer": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "STRING",
+              "value": "-"
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
+        },
+        {
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "_hex"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "_decimal"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "_octal"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "_binary"
+            }
+          ]
+        }
+      ]
+    },
+    "_hex": {
+      "type": "PATTERN",
+      "value": "0[xX][0-9a-fA-F_]+"
+    },
+    "_decimal": {
+      "type": "PATTERN",
+      "value": "[0-9][0-9_]*"
+    },
+    "_octal": {
+      "type": "PATTERN",
+      "value": "0[oO][0-7_]+"
+    },
+    "_binary": {
       "type": "PATTERN",
-      "value": "-?[0-9_]+"
+      "value": "0[bB][0-1_]+"
     },
     "_bit_string_segment_option_unit": {
       "type": "SEQ",

src/node-types.json

@@ -477,6 +477,11 @@
       ]
     }
   },
+  {
+    "type": "bit_string_segment_option_unit",
+    "named": true,
+    "fields": {}
+  },
   {
     "type": "bit_string_segment_options",
     "named": true,
@@ -1599,6 +1604,11 @@
       ]
     }
   },
+  {
+    "type": "integer",
+    "named": true,
+    "fields": {}
+  },
   {
     "type": "list",
     "named": true,
@@ -2995,10 +3005,6 @@
     "type": "bit_string_segment_option_signed",
     "named": true
   },
-  {
-    "type": "bit_string_segment_option_unit",
-    "named": true
-  },
   {
     "type": "bit_string_segment_option_unsigned",
     "named": true
@@ -3063,10 +3069,6 @@
     "type": "import",
     "named": false
   },
-  {
-    "type": "integer",
-    "named": true
-  },
   {
     "type": "javascript",
     "named": false