There now exists a problem building apps on OSX using FPC trunk sources.

Issue: Any attempt to build with a form present causes a popup dialog to be show with the message "Streaming Error Unable to Form1:TForm1 Abstract method called"

This error will occur even if you're not trying to compile a project with a form. For instance if you have a form project open, then open a package and try to build the package you will get this error. But if you start a new console project without a form, and then open and compile the same package, the package compilation or installation works.

Steps to reproduce:

Check out FPC trunk sources on OSX
Make FPC (3.1.1 the default should be darwin i386) Configure the compiler and paths
Rebuild Lazarus with the new compiler
Open Lazarus
A blank form project will be opened by default
Press build and you will receive this error

Notes:

At first I tried new Lazarus with trunk sources. When i received this error, I copied my existing and working Lazarus and compiled with the new FPC from trunk. The same behavior is exhibited, thus leading me to believe the problem s with FPC and not Lazarus.

I will attempt older FPC revisions before filing an official bug report. In the mean time if anyone can confirm or test this issue your efforts would be appreciated.