Let a glob class range start at a leading ] [patch]

TextFilter.Test/TextFilterTests.cs

@@ -1004,6 +1004,8 @@ public void ExpandGlobClassesRejectsClassesThatCannotBeListed(string token) =>
 	[DataRow("file[0-9a-]", "file5 filea file-", "fileb file_")]
 	[DataRow("[]a-]", "a - ]", "b [")]
 	[DataRow("[!]a-]", "b [", "a - ]")]
+	[DataRow("[]-a]", "] ^ _ ` a", "- b [")]
+	[DataRow("[!]-a]", "- b [", "] ^ _ ` a")]
 	[DataRow("[!-#]", "a $ ! \"", "- #")]
 	public void GlobClassMatchesEveryMemberOfEveryRange(string pattern, string matching, string notMatching)
 	{

TextFilter/TextFilter.cs

@@ -125,7 +125,7 @@
 	private static readonly TimeSpan RegexMatchTimeout = TimeSpan.FromSeconds(1);
 
 	[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "SYSLIB1045:Convert to 'GeneratedRegexAttribute'.", Justification = "Not available in older frameworks")]
 	private static Regex RegexMatchAnything() => new(".*", RegexOptions.Compiled);
 
 	// Stands in for a pattern that has already run out of time once. The timeout bounds a single
 	// IsMatch call, so without this the same pathological pattern would pay it again for every word
@@ -300,7 +300,7 @@
 
 			return ExcludedTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Excluded
 				: RequiredTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Required
 				: TextFilterTokenType.Optional;
 		})
@@ -575,7 +575,8 @@
 		while (i < content.Length)
 		{
 			char first = content[i];
-			bool isRange = i + 2 < content.Length && content[i + 1] == '-' && !(i == 0 && first == ']');
+			// A leading "]" can start a range too: "[]-a]" is "]".."a", as in POSIX.
+			bool isRange = i + 2 < content.Length && content[i + 1] == '-';
 			if (!isRange)
 			{
 				members.Add(first);