Destructor ~Loop() may throw exception (violates C++ standard and guidelines)

src/collective/loop.cc

@@ -199,7 +199,7 @@ void Loop::Process() {
   }
 }
 
-Result Loop::Stop() {
+Result Loop::Stop(bool from_destructor) {
   // Finish all remaining tasks
   CHECK_EQ(this->Block().OK(), this->rc_.OK());
 
@@ -214,7 +214,17 @@ Result Loop::Stop() {
   }
 
   if (curr_exce_) {
-    std::rethrow_exception(curr_exce_);
+    if (from_destructor) {
+      try {
+        std::rethrow_exception(curr_exce_);
+      } catch (const std::exception& e) {
+        return Fail("Exception in loop: " + std::string(e.what()));
+      } catch (...) {
+        return Fail("Unknown exception in loop");
+      }
+    } else {
+      std::rethrow_exception(curr_exce_);
+    }
   }
 
   return Success();

src/collective/loop.h

@@ -72,7 +72,7 @@ class Loop {
   /**
    * @brief Stop the worker thread.
    */
-  Result Stop();
+  Result Stop(bool from_destructor = false);
 
   void Submit(Op op);
 
@@ -84,9 +84,10 @@ class Loop {
 
   explicit Loop(std::chrono::seconds timeout);
 
-  ~Loop() noexcept(false) {
+  ~Loop() noexcept {
     // The worker will be joined in the stop function.
-    this->Stop();
+    this->Stop(true);
   }
+
 };
 }  // namespace xgboost::collective