ghOSt: Improve style of << overrides

PiperOrigin-RevId: 478907733

Author: jackhumphries

experiments/shared/thread_wait.h

@@ -62,15 +62,10 @@ inline std::ostream& operator<<(std::ostream& os,
                                 ThreadWait::WaitType wait_type) {
   switch (wait_type) {
     case ThreadWait::WaitType::kSpin:
-      os << "Spin";
-      break;
+      return os << "Spin";
     case ThreadWait::WaitType::kFutex:
-      os << "Futex";
-      break;
-      // We will get a compile error if a new member is added to the
-      // 'ThreadWait::WaitType' enum and a corresponding case is not added here.
+      return os << "Futex";
   }
-  return os;
 }
 
 }  // namespace ghost_test

lib/base.h

@@ -187,8 +187,7 @@ class Gtid {
   bool operator!() const { return id() == 0; }
 
   friend std::ostream& operator<<(std::ostream& os, const Gtid& gtid) {
-    os << gtid.id();
-    return os;
+    return os << gtid.id();
   }
 
   // These are just some simple debug helpers to make things more readable.
@@ -342,20 +341,12 @@ class Notification {
                                   Notification::NotifiedState notified_state) {
     switch (notified_state) {
       case Notification::NotifiedState::kNoWaiter:
-        os << "No Waiter";
-        break;
+        return os << "No Waiter";
       case Notification::NotifiedState::kWaiter:
-        os << "Waiter";
-        break;
+        return os << "Waiter";
       case Notification::NotifiedState::kNotified:
-        os << "Notified";
-        break;
-      default:
-        GHOST_ERROR("`notified_state` has non-enumerator value %d.",
-                    static_cast<int>(notified_state));
-        break;
+        return os << "Notified";
     }
-    return os;
   }
 
   // The notification state.

lib/channel.h

@@ -64,8 +64,7 @@ class Message {
   }
 
   friend std::ostream& operator<<(std::ostream& os, const Message& msg) {
-    os << msg.stringify();
-    return os;
+    return os << msg.stringify();
   }
 
  private:

lib/ghost.h

@@ -522,21 +522,14 @@ class GhostThread {
   GhostThread& operator=(const GhostThread&) = delete;
   ~GhostThread();
 
-  friend std::ostream& operator<<(
-      std::ostream& os, const GhostThread::KernelScheduler& kernel_scheduler) {
-    switch (kernel_scheduler) {
+  friend std::ostream& operator<<(std::ostream& os,
+                                  GhostThread::KernelScheduler scheduler) {
+    switch (scheduler) {
       case GhostThread::KernelScheduler::kCfs:
-        os << "CFS";
-        break;
+        return os << "CFS";
       case GhostThread::KernelScheduler::kGhost:
-        os << "ghOSt";
-        break;
-      default:
-        GHOST_ERROR("`kernel_scheduler` has non-enumerator value %d.",
-                    static_cast<int>(kernel_scheduler));
-        break;
+        return os << "ghOSt";
     }
-    return os;
   }
 
   // Joins the thread.

lib/topology.h

@@ -442,8 +442,7 @@ class CpuList : public CpuMap {
 
   // Dumps the bitmap in hexadecimal, highest cpus to the left
   friend std::ostream& operator<<(std::ostream& os, const CpuList& clist) {
-    os << clist.CpuMaskStr();
-    return os;
+    return os << clist.CpuMaskStr();
   }
 
  private:

schedulers/cfs/cfs_scheduler.cc

@@ -894,8 +894,6 @@ std::ostream& operator<<(std::ostream& os, const CfsTaskState& state) {
       return os << "kRunnable";
     case CfsTaskState::kNumStates:
       return os << "SENTINEL";
-      break;
-      // No default (exhaustive switch)
   }
 }
 

schedulers/edf/edf_scheduler.h

@@ -65,8 +65,7 @@ struct EdfTask : public Task<> {
 
   friend inline std::ostream& operator<<(std::ostream& os,
                                          EdfTask::RunState run_state) {
-    os << RunStateToString(run_state);
-    return os;
+    return os << RunStateToString(run_state);
   }
 
   RunState run_state = RunState::kBlocked;

schedulers/fifo/centralized/fifo_scheduler.h

@@ -48,18 +48,12 @@ struct FifoTask : public Task<> {
         return "OnCpu";
       case FifoTask::RunState::kYielding:
         return "Yielding";
-        // We will get a compile error if a new member is added to the
-        // `FifoTask::RunState` enum and a corresponding case is not added
-        // here.
     }
-    CHECK(false);
-    return "Unknown run state";
   }
 
   friend std::ostream& operator<<(std::ostream& os,
                                   FifoTask::RunState run_state) {
-    os << RunStateToString(run_state);
-    return os;
+    return os << RunStateToString(run_state);
   }
 
   RunState run_state = RunState::kBlocked;

schedulers/fifo/per_cpu/fifo_scheduler.cc

@@ -421,10 +421,7 @@ std::ostream& operator<<(std::ostream& os, const FifoTaskState& state) {
       return os << "kQueued";
     case FifoTaskState::kOnCpu:
       return os << "kOnCpu";
-      // No default (exhaustive switch)
   }
-
-  return os << static_cast<int>(state);  // 'state' has a non-enumerator value.
 }
 
 }  //  namespace ghost

schedulers/shinjuku/shinjuku_scheduler.h

@@ -83,27 +83,19 @@ struct ShinjukuTask : public Task<> {
 
   friend std::ostream& operator<<(std::ostream& os,
                                   ShinjukuTask::RunState run_state) {
-    os << RunStateToString(run_state);
-    return os;
+    return os << RunStateToString(run_state);
   }
 
   friend std::ostream& operator<<(
       std::ostream& os, ShinjukuTask::UnscheduleLevel unschedule_level) {
     switch (unschedule_level) {
       case ShinjukuTask::UnscheduleLevel::kNoUnschedule:
-        os << "No Unschedule";
-        break;
+        return os << "No Unschedule";
       case ShinjukuTask::UnscheduleLevel::kCouldUnschedule:
-        os << "Could Unschedule";
-        break;
+        return os << "Could Unschedule";
       case ShinjukuTask::UnscheduleLevel::kMustUnschedule:
-        os << "Must Unschedule";
-        break;
-        // We will get a compile error if a new member is added to the
-        // `ShinjukuTask::UnscheduleLevel` enum and a corresponding case is not
-        // added here.
+        return os << "Must Unschedule";
     }
-    return os;
   }
 
   RunState run_state = RunState::kBlocked;