Andreas, I was watching an old video of yours, where you were adding for_each_widget, for_each_widget_of_type<>, etc. In the video, you bemoaned having to turn your nice one-line native loops into for_each calls with two-lined bodies, since you needed to now return IterationDecision::Continue. But since you use a modern compiler, you can use "if constexpr" to get rid of the need for returning an IterationDecision if it can be assumed to always return IterationDecision::Continue (which is likely the common case, so we optimize for that).

Here's an example patch for for_each_in_pgrp() in Kernel/Process.h. There are four places where for_each_in_pgrp() is called: two returning Continue and two returning Break. Those first two can be changed to return nothing, as shown below.

diff --git a/Kernel/Process.h b/Kernel/Process.h
index 7848baa31..4edaf32e7 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -51,6 +51,7 @@
 #include <Kernel/VM/Space.h>
 #include <LibC/signal_numbers.h>
 #include <LibELF/exec_elf.h>
+#include <type_traits>
 
 namespace Kernel {
 
@@ -693,8 +694,12 @@ inline void Process::for_each_in_pgrp(ProcessGroupID pgid, Callback callback)
     for (auto* process = g_processes->head(); process;) {
         auto* next_process = process->next();
         if (!process->is_dead() && process->pgid() == pgid) {
-            if (callback(*process) == IterationDecision::Break)
-                break;
+            if constexpr (std::is_void_v<std::invoke_result_t<Callback, decltype(*process)>>) {
+                callback(*process);
+            } else {
+                if (callback(*process) == IterationDecision::Break)
+                    break;
+            }
         }
         process = next_process;
     }
diff --git a/Kernel/Syscalls/kill.cpp b/Kernel/Syscalls/kill.cpp
index 48eb07fd2..1a9c86fc8 100644
--- a/Kernel/Syscalls/kill.cpp
+++ b/Kernel/Syscalls/kill.cpp
@@ -67,8 +67,6 @@ KResult Process::do_killpg(ProcessGroupID pgrp, int signal)
             any_succeeded = true;
         else
             error = res;
-
-        return IterationDecision::Continue;
     });
 
     if (group_was_empty)
diff --git a/Kernel/TTY/TTY.cpp b/Kernel/TTY/TTY.cpp
index b4544e09b..a4dd4e994 100644
--- a/Kernel/TTY/TTY.cpp
+++ b/Kernel/TTY/TTY.cpp
@@ -289,7 +289,6 @@ void TTY::generate_signal(int signal)
         dbgln_if(TTY_DEBUG, "{}: Send signal {} to {}", tty_name(), signal, process);
         // FIXME: Should this error be propagated somehow?
         [[maybe_unused]] auto rc = process.send_signal(signal, nullptr);
-        return IterationDecision::Continue;
     });
 }