fix compiler warnings

src/task.c

@@ -169,7 +169,7 @@ static void NOINLINE save_stack(jl_task_t *t)
     size_t nb = (char*)jl_stackbase - (char*)&_x;
     char *buf;
     if (t->stkbuf == NULL || ((size_t*)t->stkbuf)[-1] < nb) {
-        buf = (char*)realloc(t->stkbuf ? t->stkbuf - sizeof(size_t) : NULL,
+        buf = (char*)realloc(t->stkbuf ? (char*)t->stkbuf - sizeof(size_t) : NULL,
                 nb + sizeof(size_t));
         if (buf == NULL)
             jl_throw(jl_memory_exception);
@@ -216,7 +216,7 @@ static void NORETURN finish_task(jl_task_t *t, jl_value_t *resultval)
     void *stkbuf = t->stkbuf;
     if (t->copy_stack && stkbuf != NULL && stkbuf != (void*)(intptr_t*)-1) {
         t->stkbuf = (void*)(intptr_t)-1;
-        free(stkbuf - sizeof(size_t));
+        free((char*)stkbuf - sizeof(size_t));
     }
 #endif
     if (ti_tid != 0) {
@@ -305,7 +305,7 @@ static void ctx_switch(jl_task_t *t)
 
 #ifdef COPY_STACKS
     if (t->copy_stack && t->stkbuf) // task already exists, resume from the copy-stack
-        restore_stack(t, lastt->copy_stack ? NULL : (void*)(intptr_t)1); // resume at jl_setjmp of the other task after restoring the stack (doesn't return)
+        restore_stack(t, lastt->copy_stack ? NULL : (char*)(intptr_t)1); // resume at jl_setjmp of the other task after restoring the stack (doesn't return)
 #endif
 
     if (!t->copy_stack && !t->stkbuf) // task not started yet, jump to start_task
@@ -755,7 +755,7 @@ static void jl_task_cleanup(jl_task_t *t)
     if (stk && stk != (void*)(intptr_t)-1) {
         t->stkbuf = (void*)(intptr_t)-1;
         if (t->copy_stack)
-            free(stk - sizeof(size_t));
+            free((char*)stk - sizeof(size_t));
         else
 #ifdef _OS_WINDOWS_
             DeleteFiber(t->fiber);
@@ -1087,7 +1087,7 @@ void jl_init_root_task(void *stack, size_t ssize)
     jl_set_typeof(jl_current_task, jl_task_type);
 
     jl_current_task->copy_stack = 0;
-    jl_current_task->stkbuf = stack - ssize - 3000000; // guess at address of bottom of stack
+    jl_current_task->stkbuf = (char*)stack - ssize - 3000000; // guess at address of bottom of stack
     jl_current_task->ssize = ssize + 3000000; // guess at sizeof stack
     jl_current_task->parent = jl_current_task;
     jl_current_task->current_module = jl_current_module;