BUG? Named numbered groups that are too large cannot be directly accessed

[longxya]

Description

If name of Named group is a number, and the number is larger than the count of Groups,using Match.Groups to check the groups in quick check in visual studio, u will find wrong infomation of this group. But u can use Match.Groups[number] to accesse this group.

Reproduction Steps

using System;
using System.Text.RegularExpressions;

var pattern = @"(?'2'.)";
//pattern = @"(?'2'.)(?'wtf')";//use this will Output normal result
var input = @"1";
var mh = Regex.Match(input,pattern);
Console.WriteLine(string.Join(",",mh.Groups.Keys)+"#");
Console.WriteLine(mh.Groups[1].Success);
Console.WriteLine(mh.Groups[2].Success);
Console.WriteLine(mh.Groups[2]);

Output:

0,#
False
True
1

Expected behavior

Output:

0,2#
False
True
1

Actual behavior

OUtput:

0,#
False
True
1

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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[longxya]

@stephentoub
Just like this:

[longxya]

Use Group.Name cannot get the name of such a group:

using System;
using System.Text.RegularExpressions;

string input = "1";
string pattern = @"(?'2'.)";
try
{
	var regex=new Regex(pattern, RegexOptions.None);
	Match match = regex.Match(input);
	var groupNums = regex.GetGroupNumbers();
	for (int i = 0; i < groupNums.Length; i++)
	{
		var group=match.Groups[groupNums[i]];
		Console.WriteLine($"Group{groupNums[i]} : Group.Name:'{group.Name}', Real Name:'{regex.GroupNameFromNumber(groupNums[i])}'  Success: {group.Success}");
	}
}
catch(Exception ex)
{
	Console.WriteLine($"Exception: {ex.Message}");
}

Output:

Group0 : Group.Name:'0', Real Name:'0'  Success: True
Group2 : Group.Name:'', Real Name:'2'  Success: True