Bug 185 - IsAssignableFrom is incorrect for generics based on assignable types.
Summary: IsAssignableFrom is incorrect for generics based on assignable types.
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: 2.10.x
Hardware: Macintosh Mac OS
: --- major
Target Milestone: Untriaged
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2011-08-05 00:45 UTC by Sergey
Modified: 2011-08-19 18:37 UTC (History)
3 users (show)

Tags: reflection, generics, IsAssignableFrom
Is this bug a regression?: ---
Last known good build:


Attachments
A test file exposing the error (272 bytes, application/octet-stream)
2011-08-05 00:45 UTC, Sergey
Details


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Status:
RESOLVED FIXED

Description Sergey 2011-08-05 00:45:39 UTC
Created attachment 71 [details]
A test file exposing the error

The algorithm for determining if a generic type is assignable from another type is broken in 4.0. The expression below

typeof(IEnumerable<int?>).IsAssignableFrom(typeof(IEnumerable<int>))

returns True, when it should return False.

This used to work in 2.0, 3.0, and 3.5. It also returns False in Microsoft .NET 4.0 on Windows.

Steps to reproduce:
    Compile the attached file using "dmcs Main.cs" command
    Run using "mono Main.cs" command

Expected output:
    False

Actual output:
    True
Comment 1 Rodrigo Kumpera 2011-08-19 18:37:28 UTC
Fixed in master/2.10 and mobile