Bug 5984 - string::Format handles incorrectly custom providers
Summary: string::Format handles incorrectly custom providers
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: master
Hardware: PC Linux
: Low normal
Target Milestone: Untriaged
Assignee: Marek Safar
URL:
Depends on:
Blocks:
 
Reported: 2012-07-05 05:10 UTC by Marek Safar
Modified: 2015-03-25 10:09 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Related Links:
Status:
RESOLVED FIXED

Description Marek Safar 2012-07-05 05:10:29 UTC
using System;

namespace Slask
{
	class MyFormatter: IFormatProvider, ICustomFormatter
	{
		public string Format(string format, object arg, IFormatProvider provider)
		{
			Console.WriteLine("Format:" + format);
			return "res";
		}
		
		public object GetFormat(Type formatType)
		{
			return this;
		}
	}
	
	class MyFormatter2: IFormatProvider, ICustomFormatter
	{
		public string Format(string format, object arg, IFormatProvider provider)
		{
			return null;
		}
		
		public object GetFormat(Type formatType)
		{
			return this;
		}
	}

	class Program
	{
		public static void Main(string[] args)
		{
			Console.WriteLine(string.Format(new MyFormatter (), "{0:}}}", "asdf"));
			Console.WriteLine(string.Format(new MyFormatter2 (), "{0:}}}", "asdf"));
		}
	}
}


.NET output

Format:}
res
asdf

Mono output

Format:
res}

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object
Comment 1 Marek Safar 2015-03-25 10:09:13 UTC
Fixed in master