Implementes the block ABI.2010.3.16 natively via the objc_block intrinsic and the Objc_Block builtin type.

See: https://clang.llvm.org/docs/Block-ABI-Apple.html

base/intrinsics/intrinsics.odin

@@ -381,6 +381,7 @@ objc_register_selector :: proc($name: string) -> objc_SEL   ---
 objc_find_class        :: proc($name: string) -> objc_Class ---
 objc_register_class    :: proc($name: string) -> objc_Class ---
 objc_ivar_get          :: proc(self: ^$T) -> ^$U ---
+objc_block             :: proc(invoke: $T, ..any) -> ^Objc_Block(T) where type_is_proc(T) ---
 
 valgrind_client_request :: proc(default: uintptr, request: uintptr, a0, a1, a2, a3, a4: uintptr) -> uintptr ---
 

base/runtime/core_builtin.odin

@@ -5,6 +5,11 @@ import "base:intrinsics"
 @builtin
 Maybe :: union($T: typeid) {T}
 
+/*
+Represents an Objective-C block with a given procedure signature T
+*/
+@builtin
+Objc_Block :: struct($T: typeid) where intrinsics.type_is_proc(T) { using _: intrinsics.objc_object }
 
 /*
 Recovers the containing/parent struct from a pointer to one of its fields.

base/runtime/procs_darwin.odin

@@ -1,9 +1,12 @@
 #+private
 package runtime
 
-@(priority_index=-1e6)
+@(priority_index=-1e5)
 foreign import ObjC "system:objc"
 
+@(priority_index=-1e6)
+foreign import libSystem "system:System"
+
 import "base:intrinsics"
 
 objc_id    :: ^intrinsics.objc_object
@@ -34,3 +37,10 @@ foreign ObjC {
 	object_getClass           :: proc "c" (obj: objc_id) -> objc_Class ---
 }
 
+foreign libSystem {
+	_NSConcreteGlobalBlock: intrinsics.objc_class
+	_NSConcreteStackBlock:  intrinsics.objc_class
+
+	_Block_object_assign  :: proc "c" (rawptr, rawptr, i32) ---
+	_Block_object_dispose :: proc "c" (rawptr, i32) ---
+}