Cast IMPs to the correct signature before calling

arc.mm

@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <atomic>
+#include <type_traits>
 #include <vector>
 #include <tsl/robin_map.h>
 #import "lock.h"
@@ -250,9 +251,11 @@ static TLS_CALLBACK(cleanupPools)(struct arc_tls* tls)
 
 
 static Class AutoreleasePool;
-static IMP NewAutoreleasePool;
-static IMP DeleteAutoreleasePool;
-static IMP AutoreleaseAdd;
+template<typename Return, typename... Arguments>
+using Selector = Return (*)(id, SEL, Arguments...);
+static Selector<id> NewAutoreleasePool;
+static Selector<void> DeleteAutoreleasePool;
+static Selector<void, id> AutoreleaseAdd;
 
 static BOOL useARCAutoreleasePool;
 
@@ -566,12 +569,14 @@ static inline void initAutorelease(void)
 			if (!useARCAutoreleasePool)
 			{
 				[AutoreleasePool class];
-				NewAutoreleasePool = class_getMethodImplementation(object_getClass(AutoreleasePool),
-				                                                   SELECTOR(new));
-				DeleteAutoreleasePool = class_getMethodImplementation(AutoreleasePool,
-				                                                      SELECTOR(release));
-				AutoreleaseAdd = class_getMethodImplementation(object_getClass(AutoreleasePool),
-				                                               SELECTOR(addObject:));
+				auto storeSelector = [](auto &target, Class cls, SEL selector)
+				{
+					target = reinterpret_cast<std::remove_reference_t<decltype(target)>>(
+						class_getMethodImplementation(cls, selector));
+				};
+				storeSelector(NewAutoreleasePool, object_getClass(AutoreleasePool), SELECTOR(new));
+				storeSelector(DeleteAutoreleasePool, AutoreleasePool, SELECTOR(release));
+				storeSelector(AutoreleaseAdd, object_getClass(AutoreleasePool), SELECTOR(addObject:));
 			}
 		}
 	}

class.h

@@ -5,6 +5,9 @@
 #include "sarray2.h"
 #include <stdint.h>
 
+typedef id (*CXXConstructIMP)(id, SEL);
+typedef void (*CXXDestructIMP)(id, SEL);
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -107,12 +110,12 @@ struct objc_class
 	 * Pointer to the .cxx_construct method if one exists.  This method needs
 	 * to be called outside of the normal dispatch mechanism.
 	 */
-	IMP                        cxx_construct;
+	CXXConstructIMP             cxx_construct;
 	/**
 	 * Pointer to the .cxx_destruct method if one exists.  This method needs to
 	 * be called outside of the normal dispatch mechanism.
 	 */
-	IMP                        cxx_destruct;
+	CXXDestructIMP              cxx_destruct;
 	/**
 	 * A pointer to the next sibling class to this.  You may find all
 	 * subclasses of a given class by following the subclass_list pointer and

dtable.c

@@ -381,11 +381,11 @@ static BOOL installMethodInDtable(Class class,
 	}
 	if (selEqualUnTyped(method->selector, cxx_construct))
 	{
-		class->cxx_construct = method->imp;
+		class->cxx_construct = (CXXConstructIMP)method->imp;
 	}
 	else if (selEqualUnTyped(method->selector, cxx_destruct))
 	{
-		class->cxx_destruct = method->imp;
+		class->cxx_destruct = (CXXDestructIMP)method->imp;
 	}
 
 	for (struct objc_class *subclass=class->subclass_list ; 
@@ -673,6 +673,7 @@ LEGACY void update_dispatch_table_for_class(Class cls)
 }
 
 BOOL objc_resolve_class(Class);
+typedef void (*InitializeIMP)(id, SEL);
 
 __attribute__((unused)) static void objc_release_object_lock(id *x)
 {
@@ -851,6 +852,6 @@ OBJC_PUBLIC void objc_send_initialize(id object)
 	// Store the buffer in the temporary dtables list.  Note that it is safe to
 	// insert it into a global list, even though it's a temporary variable,
 	// because we will clean it up after this function.
-	initializeSlot->imp((id)class, initializeSel);
+	InitializeIMP initialize = (InitializeIMP)initializeSlot->imp;
+	initialize((id)class, initializeSel);
 }
-

runtime.c

@@ -846,4 +846,3 @@ void objc_registerClassPair(Class cls)
 	class_table_insert(cls);
 	objc_resolve_class(cls);
 }
-