Everywhere: Switch from (void) to [[maybe_unused]] (#4473)

Problem:
- `(void)` simply casts the expression to void. This is understood to
  indicate that it is ignored, but this is really a compiler trick to
  get the compiler to not generate a warning.

Solution:
- Use the `[[maybe_unused]]` attribute to indicate the value is unused.

Note:
- Functions taking a `(void)` argument list have also been changed to
  `()` because this is not needed and shows up in the same grep
  command.

1 files changed, 9 insertions, 12 deletions

diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp
index 0df5f639b7..b863ab2597 100644
--- a/Kernel/Arch/i386/CPU.cpp
+++ b/Kernel/Arch/i386/CPU.cpp
@@ -64,9 +64,9 @@ static GenericInterruptHandler* s_interrupt_handler[GENERIC_INTERRUPT_HANDLERS_C
 extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread);
 extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap);
 extern "C" u32 do_init_context(Thread* thread, u32 flags);
-extern "C" void exit_kernel_thread(void);
-extern "C" void pre_init_finished(void);
-extern "C" void post_init_finished(void);
+extern "C" void exit_kernel_thread();
+extern "C" void pre_init_finished();
+extern "C" void post_init_finished();
 extern "C" void handle_interrupt(TrapFrame*);
 
 #define EH_ENTRY(ec, title)                         \
@@ -1490,13 +1490,10 @@ void Processor::switch_context(Thread*& from_thread, Thread*& to_thread)
 #endif
 }
 
-extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap)
+extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe_unused]] Thread* to_thread, [[maybe_unused]] TrapFrame* trap)
 {
     ASSERT(!are_interrupts_enabled());
     ASSERT(is_kernel_mode());
-    (void)from_thread;
-    (void)to_thread;
-    (void)trap;
 
 #ifdef CONTEXT_SWITCH_DEBUG
     dbg() << "switch_context <-- from " << VirtualAddress(from_thread) << " " << *from_thread << " to " << VirtualAddress(to_thread) << " " << *to_thread << " (context_first_init)";
@@ -1513,7 +1510,7 @@ extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapF
     Scheduler::leave_on_first_switch(trap->regs->eflags);
 }
 
-extern "C" void thread_context_first_enter(void);
+extern "C" void thread_context_first_enter();
 asm(
 // enter_thread_context returns to here first time a thread is executing
 ".globl thread_context_first_enter \n"
@@ -1529,7 +1526,7 @@ asm(
 "    jmp common_trap_exit \n"
 );
 
-void exit_kernel_thread(void)
+void exit_kernel_thread()
 {
     Thread::current()->exit();
 }
@@ -1674,7 +1671,7 @@ void Processor::assume_context(Thread& thread, u32 flags)
     ASSERT_NOT_REACHED();
 }
 
-extern "C" void pre_init_finished(void)
+extern "C" void pre_init_finished()
 {
     ASSERT(g_scheduler_lock.own_lock());
 
@@ -1687,7 +1684,7 @@ extern "C" void pre_init_finished(void)
     Scheduler::leave_on_first_switch(prev_flags);
 }
 
-extern "C" void post_init_finished(void)
+extern "C" void post_init_finished()
 {
     // We need to re-acquire the scheduler lock before a context switch
     // transfers control into the idle loop, which needs the lock held
@@ -1731,7 +1728,7 @@ void Processor::initialize_context_switching(Thread& initial_thread)
            [from_to_thread] "b" (&initial_thread),
            [cpu] "c" (id())
     );
-    
+
     ASSERT_NOT_REACHED();
 }