From 6d47b919e62fa60453808745f07b3d1e9feded77 Mon Sep 17 00:00:00 2001
From: Jonas Rembser <jonas.rembser@cern.ch>
Date: Fri, 19 Apr 2024 01:21:12 +0200
Subject: [PATCH] [RF] Throw exception if element in `RooAbsCollection` can't
 be replaced

This would leave the collection in an undesired state, so it's not good
to continue at that point.
---
 roofit/roofitcore/src/RooAbsCollection.cxx | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/roofit/roofitcore/src/RooAbsCollection.cxx b/roofit/roofitcore/src/RooAbsCollection.cxx
index b906d628a47d6..edf331341a6d4 100644
--- a/roofit/roofitcore/src/RooAbsCollection.cxx
+++ b/roofit/roofitcore/src/RooAbsCollection.cxx
@@ -536,8 +536,11 @@ bool RooAbsCollection::replace(const RooAbsCollection &other)
 {
   // check that this isn't a copy of a list
   if(_ownCont) {
-    coutE(ObjectHandling) << "RooAbsCollection: cannot replace variables in a copied list" << std::endl;
-    return false;
+    std::stringstream errMsg;
+    errMsg << "RooAbsCollection: cannot replace variables in a copied list";
+    coutE(ObjectHandling) << errMsg.str() << std::endl;
+    // better than returning "false" and leaving the collection in a broken state:
+    throw std::invalid_argument(errMsg.str());
   }
 
   // loop over elements in the other list
@@ -561,8 +564,11 @@ bool RooAbsCollection::replace(const RooAbsArg& var1, const RooAbsArg& var2)
 {
   // check that this isn't a copy of a list
   if(_ownCont) {
-    coutE(ObjectHandling) << "RooAbsCollection: cannot replace variables in a copied list" << std::endl;
-    return false;
+    std::stringstream errMsg;
+    errMsg << "RooAbsCollection: cannot replace variables in a copied list";
+    coutE(ObjectHandling) << errMsg.str() << std::endl;
+    // better than returning "false" and leaving the collection in a broken state:
+    throw std::invalid_argument(errMsg.str());
   }
 
   // is var1 already in this list?