Bug 6987 - error MT2002: Can not resolve reference when building for iPhone
Summary: error MT2002: Can not resolve reference when building for iPhone
Alias: None
Product: iOS
Classification: Xamarin
Component: General ()
Version: 5.3.x
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Sebastien Pouliot
Depends on:
Reported: 2012-09-07 09:22 UTC by Bob Reck
Modified: 2012-09-07 13:17 UTC (History)
2 users (show)

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

Build output with --linkskip=IOSTChart -v -v -v in additional monotouch arguments (31.57 KB, text/rtf)
2012-09-07 09:22 UTC, Bob Reck
hotfix (3.45 MB, application/octet-stream)
2012-09-07 11:24 UTC, Sebastien Pouliot

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Description Bob Reck 2012-09-07 09:22:56 UTC
Created attachment 2473 [details]
Build output with --linkskip=IOSTChart -v -v -v in additional monotouch arguments

I am getting a strange error when building my app for debug deployment to my test device. This does not happen when compiling for the simulator. 

The specific error is: error MT2002: Can not resolve reference: 
System.Void MonoTouch.Foundation.NSTimer::.ctor() I've searched for this and found a bunch of similar error MT2002's but nothing has resolved this issue. 

I am running the MonoDevelop and MonoTouch 5.4.0. 

I have posted about this to the MonoTouch forums. Sebastien was trying to help me and suggested that it was a 3rd party DLL that was causing the problem.  I have one (IOSTChart.dll) from Steema for charting purposes. Sebastien had suggested that I use the "--linkskip=IOSTChart" in the additional monotouch arguments field. Trying that did not remove the build error.

The only other references I have are: 

Sebastien requested that I submit this bug report and include the build output (attached). 

Please let me know if you need more information to make sense of this. Thank you! 
Comment 1 Sebastien Pouliot 2012-09-07 10:25:39 UTC
IOSTChart does refer to the broken NSTimer ctor. Sadly "linkskip" won't be enough (you can remove it from your options) as, by default, the linker will need to process the IOSTChart assembly anyway.

Two things you can try (quickly):

1. Use "Link all assemblies". That will "likely" remove the code that use the invalid NSTimer. However if your application use (even indirectly) reflection you might run into other issues.

2. Use "Don't link". That will not run the linker but your application will be *much* larger (and will take more time to compile and upload to devices).

In the meantime I'll re-introduce the broken .ctor in a way that people can't use in (in new code) but make it available (as a symbol) for existing assembly binaries. I'll attach an hotfix (with instructions) once I tested it.
Comment 2 Sebastien Pouliot 2012-09-07 11:23:12 UTC
master: c396ab596f14889438a4526d1c022707fd1ac4bc
monotouch-5.4-series: 6f74748b37404f6ab464f785029ec48f06de5737
Comment 3 Sebastien Pouliot 2012-09-07 11:24:47 UTC
Created attachment 2476 [details]

To use the attached assembly (on top of MonoTouch 5.4.0) do:

1) backup your /Developer/MonoTouch/usr/lib/mono/2.1/monotouch.dll and /Developer/MonoTouch/usr/lib/mono/2.1/monotouch.dll.mdb files

2) copy the attached file to /Developer/MonoTouch/usr/lib/mono/2.1/monotouch.dll

3) remove the /Developer/MonoTouch/usr/lib/mono/2.1/monotouch.dll.mdb symbols (they won't match anymore)

4) clean, rebuild and test your application

Once you update to 5.4.1 the fix will be part of MonoTouch and this won't be required anymore.
Comment 4 Bob Reck 2012-09-07 12:12:46 UTC
Thank you Sebastien. Will let you know the results when I have this hotfix in place.
Comment 5 Bob Reck 2012-09-07 12:19:36 UTC
Ok, I feel like a complete tool, but can you give me some instruction on how to find those files? I'm a windows user who is still very much a Mac newbie.  Sorry and thanks!
Comment 6 Bob Reck 2012-09-07 12:47:38 UTC
Nevermind... found it. Thanks.
Comment 7 Bob Reck 2012-09-07 12:59:15 UTC
YES! It works! Thank you Sebastien!
Comment 8 Sebastien Pouliot 2012-09-07 13:17:57 UTC
Sorry it was lunch time - but I'm glad you got it working. Have fun!