fix clang generated code

interpreter/Makefile

 TARGET = main
 LIBS =
-CC = g++
+CC = clang++
 CFLAGS = -g -Wno-write-strings
 
 .PHONY: default all clean

interpreter/code.c

@@ -170,4 +170,6 @@ exec(Code* expr, int frame_ptr, Thunk* target, bool force)
         printf("Exec: Unhandled CODE type");
         exit(-1);
     }
+    
+    return NULL;
 }

interpreter/thunk.h

@@ -21,6 +21,8 @@ typedef struct __attribute__((packed)) Thunk {
     };
 } Thunk;
 
+#pragma pack(pop)
+
 Thunk* forward_to(Thunk* target, Thunk* thunk);
 
 struct Thunk* updateI(Thunk* target, int i);