accept tabs as whitespace

corpus/shebang.txt

@@ -15,6 +15,26 @@ nix-shell shebang whitespace
 #! /usr/bin/env nix-shell
 ---
 
+(source_file
+  (first_line))
+
+==================
+nix-shell shebang tab
+==================
+
+#!	/usr/bin/env	nix-shell
+---
+
+(source_file
+  (first_line))
+
+==================
+nix-shell shebang tabs and spaces
+==================
+
+#!	  /usr/bin/env 	 	nix-shell
+---
+
 (source_file
   (first_line))
 

grammar.js

@@ -55,8 +55,12 @@ module.exports = grammar({
       'env',
     ),
     _nix_shell: $ => 'nix-shell',
-    _ws: $ => / +/,
+    // N.B.: this accepts more than it needs to:
-    _opt_ws: $ => / */,
+    // - shebang parser allows tab characters
+    // - #!nix-shell directives do not support tabs
+    // - wherever #!nix-shell directives allow whitespace, it's a *single* space -- never multiple
+    _ws: $ => /[ \t]+/,
+    _opt_ws: $ => /[ \t]*/,
     _newline: $ => '\n',
   }
 });