coroutines: get photonlib/coroutines working with GC

thirdparty/photon/photonwrapper.h

@@ -24,8 +24,10 @@ int photon_init_default();
 void photon_thread_create(void* (* f)(void*), void* arg);
 void photon_sleep_s(int n);
 void photon_sleep_ms(int n);
-
-
+void set_photon_thread_stack_allocator(
+    void* (*alloc_func)(void*, size_t),
+    void (*dealloc_func)(void*, void*, size_t)
+);
 
 #ifdef __cplusplus
 }

vlib/builtin/builtin_d_gcboehm.c.v

@@ -139,3 +139,6 @@ pub fn gc_check_leaks() {
 
 fn C.GC_get_heap_usage_safe(pheap_size &usize, pfree_bytes &usize, punmapped_bytes &usize, pbytes_since_gc &usize, ptotal_bytes &usize)
 fn C.GC_get_memory_use() usize
+
+fn C.GC_add_roots(voidptr, voidptr)
+fn C.GC_remove_roots(voidptr, voidptr)

vlib/coroutines/coroutines.v

@@ -14,13 +14,28 @@ fn C.photon_init_default() int
 fn C.photon_thread_create(f voidptr, arg voidptr)
 fn C.photon_sleep_s(n int)
 fn C.photon_sleep_ms(n int)
+fn C.set_photon_thread_stack_allocator(fn (voidptr, int) voidptr, fn (voidptr, voidptr, int))
 
 // sleep is coroutine-safe version of time.sleep()
 pub fn sleep(duration time.Duration) {
 	C.photon_sleep_ms(duration.milliseconds())
 }
 
 fn init() {
+	alloc := fn (_ voidptr, stack_size int) voidptr {
+		unsafe {
+			stack_ptr := malloc(stack_size)
+			C.GC_add_roots(stack_ptr, charptr(stack_ptr) + stack_size)
+			return stack_ptr
+		}
+	}
+	dealloc := fn (_ voidptr, stack_ptr voidptr, stack_size int) {
+		unsafe {
+			C.GC_add_roots(stack_ptr, charptr(stack_ptr) + stack_size)
+			free(stack_ptr)
+		}
+	}
+	C.set_photon_thread_stack_allocator(alloc, dealloc)
 	ret := C.photon_init_default()
 	if ret < 0 {
 		panic('failed to initialize coroutines via photon (ret=${ret})')