Smaller test case

blort.lisp

#+sbcl
(eval-when (:compile-toplevel :load-toplevel :execute)
  (sb-int:set-floating-point-modes :traps nil))

(defpackage :a (:use :cl))

(in-package :a)

(cffi:define-foreign-library blort
  (:darwin "/Users/Baggers/Library/Developer/Xcode/DerivedData/blort-ewxiurstjoibccbijgkxqrtyvtbu/Build/Products/Debug/libblort.dylib"))

(cffi:use-foreign-library blort)

(defun print! (x &rest args)
  (format t "~%~a~{ ~s~}" x args)
  (finish-output)
  x)

;;void SDL_PumpEvents(void)
(cffi:defcfun ("Cocoa_Init" sdl_init) :void)
(cffi:defcfun ("Cocoa_PumpEvents" sdl_pump_events) :void)

(defun my-init ()
  (sdl_init))

(defun my-pump ()
  (sdl_pump_events))

(defun b ()
  #+ccl(let ((thread (find 0 (ccl:all-processes) :key #'ccl:process-serial-number)))
		 (ccl:process-interrupt thread #'do-it))
  #-ccl(do-it))

(defun do-it ()
  (print! "hi")
  (my-init)
  (print! "next will poll a single event a bunch of times")
  (print! (bt:all-threads))
  (print! (bt:current-thread))
  (loop :for i :below 300 :do (my-pump))
  (print! "done"))

blort.m

#import "blort.h"
#include <ApplicationServices/ApplicationServices.h>
#include <Cocoa/Cocoa.h>

@interface BlortAppDelegate : NSObject <NSApplicationDelegate>
@end

@implementation BlortAppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSLog(@"applicationDidFinishLaunching");
    [NSApp activateIgnoringOtherApps:YES];
}
@end

static BlortAppDelegate *appDelegate = nil;

extern void Cocoa_Init(void)
{ @autoreleasepool
    {
        [NSApplication sharedApplication];
        [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
        NSLog(@"\nFOIRST TROII!");
        [NSApp setDelegate:[[BlortAppDelegate alloc] init]];
        [NSApp finishLaunching];
    }
}
extern void Cocoa_PumpEvents(void)
{ @autoreleasepool
    {
        NSEvent* event = [NSApp nextEventMatchingMask:NSEventMaskAny untilDate:[NSDate distantPast] inMode:NSDefaultRunLoopMode dequeue:YES ];
    }
}

In xcode make a library project, add the Cocoa.framework, build.

Tweak blort.lisp to give it to correct path

Doesnt crash ccl but does sbcl.

This code needs understanding and reducing further before we report this to any implementation. They shouldnt have to deal with this.