Notice (2018-05-24): bugzilla.xamarin.com is now in
Please join us on
Visual Studio Developer Community and in the
Mono organizations on
GitHub to continue tracking issues. Bugzilla will remain
available for reference in read-only mode. We will continue to work
on open Bugzilla bugs, copy them to the new locations
as needed for follow-up, and add the new items under Related
Our sincere thanks to everyone who has contributed on this bug
tracker over the years. Thanks also for your understanding as we
make these adjustments and improvements for the future.
Please create a new report on
GitHub or Developer Community with
your current version information, steps to reproduce, and relevant error
messages or log files if you are hitting an issue that looks similar to
this resolved bug and you do not yet see a matching new report.
While working with a structure defined with [StructLayout(LayoutKind.Explicit)] and [FieldOffset(n)], I noticed that .NET throws an exception when loading the assembly if I overlap structs and references. Mono doesn't. The restriction seems to make sense in the presence of a precise GC - If I overlap my reference with a double, should I consider it a reference or a double?
Furthermore, there are weird crashes on Mono when using structures with a struct/reference overlap :-)
The code that I used: https://github.com/mbrezu/Shovel/blob/master/csharp/NShovel/Shovel/Value.cs (it is now fixed to eliminate the overlap, replace FieldOffset(8) with FieldOffset(0) to reintroduce it).
A simplified use case that is rejected by .NET and accepted by Mono:
public struct Value
public double DoubleValue;
public object ObjectValue;
static void Main(string args)
This is only checked if the verifier is enabled. This is by design.