[Mono-list] Delegates and inter-assembly custom marshaler lookup

[Patrick Hartling]

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I have run across what I think is a bug in Mono's lookup of custom
marshalers associated with delegates.  The problem occurs when a
delegate defined in a base class (A.Base in assembly A.dll) has a custom
marshaler for a parameter.  If a class drived from A.Base in a different
assembly (B.Derived in assembly B.dll) tries to pass the delegate as a
function pointer to native code, Mono 0.29 hits an assertion failure on
line 2069 of mono/metadata/marshal.c (line 2082 for today's snapshot).

At a high level, mono_reflection_type_from_name() is returning NULL for
the custom marshaler type in question, though I have not nailed down
exactly why this is happening.  In mono_reflection_type_from_name(),
info.assembly.name comes back NULL after the call to
mono_reflection_parse_type().  I think that if info.assembly.name were
not NULL, the correct assembly image would be found to get the custom
marshaler.

I have attached C# and C++ code with a makefile that can be used to
repeat the problem I am running into.  I have verified that this code
works with the .NET Framework versions 1.0 and 1.1 (compiling the C++
code with Visual C++ 7.0 and 7.1 to match the .NET Framework version
accordingly).  The code is more complicated than I would like it to be,
but to the best of my current understanding, it is the least amount of
code I can come up with to demonstrate the crash.  Note that in B.cs, a
custom marshaler from the assembly A is used for a P/Invoke call, and it
works fine.  For that reason, I concluded that the lookup problem is
related to delegates.

Looking through Bugzilla, it looks as though the first C# attachment
with Bug 43351
(http://bugzilla.ximian.com/showattachment.cgi?attach_id=3D4400) is
related to what I am running into, but that code runs correctly with
Mono 0.29.  My guess is that the difference between the two cases is
that I am trying to access a delegate in an external assembly whereas
Marcus' example is contained within a single assembly.

 -Patrick


--=20
Patrick L. Hartling                     | Research Assistant, VRAC
patrick@vrac.iastate.edu                | 2274 Howe Hall Room 2624
http://www.vrac.iastate.edu/~patrick/   | http://www.vrac.iastate.edu/
PGP: http://wwwkeys.gpg.cz:11371/pks/lookup?op=3Dget&search=3D0xEBF86398


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