From f24b03fc7f9cf6c09607a1ffca6af2f893e3da09 Mon Sep 17 00:00:00 2001
From: Max Sagebaum <max.sagebaum@scicomp.uni-kl.de>
Date: Wed, 3 Apr 2024 13:58:53 +0200
Subject: [PATCH] Bugfix for false positive of the tagging tape for MPI reduce
 operations.

---
 include/codi/tapes/tagging/tagTapeBase.hpp    | 5 +++--
 include/codi/tapes/tagging/tagTapeReverse.hpp | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/codi/tapes/tagging/tagTapeBase.hpp b/include/codi/tapes/tagging/tagTapeBase.hpp
index c203490a..60a564e0 100644
--- a/include/codi/tapes/tagging/tagTapeBase.hpp
+++ b/include/codi/tapes/tagging/tagTapeBase.hpp
@@ -85,7 +85,8 @@ namespace codi {
       /// Callback for a tag error.
       using TagErrorCallback = void (*)(Tag const& correctTag, Tag const& wrongTag, void* userData);
 
-      static Tag constexpr PassiveTag = Tag(0);  ///< Tag indicating an inactive value.
+      static Tag constexpr PassiveTag = Tag(0);   ///< Tag indicating an inactive value.
+      static Tag constexpr InvalidTag = Tag(-1);  ///< Tag indicating an invalid value.
 
     protected:
 
@@ -223,7 +224,7 @@ namespace codi {
 
       /// Checks if the tag is correct. Errors are set on the ValidationIndicator object.
       CODI_INLINE void verifyTag(ValidationIndicator<Real, Tag>& vi, Tag const& tag) const {
-        if (PassiveTag != tag) {
+        if (PassiveTag != tag && InvalidTag != tag) {
           vi.isActive = true;
           if (tag != curTag) {
             vi.hasError = true;
diff --git a/include/codi/tapes/tagging/tagTapeReverse.hpp b/include/codi/tapes/tagging/tagTapeReverse.hpp
index 251dd3f1..2eda2ed1 100644
--- a/include/codi/tapes/tagging/tagTapeReverse.hpp
+++ b/include/codi/tapes/tagging/tagTapeReverse.hpp
@@ -250,7 +250,7 @@ namespace codi {
 
       /// -1 tag.
       Identifier getInvalidIndex() const {
-        return Identifier(-1);
+        return Identifier(Base::InvalidTag);
       }
 
       /// Verify tag.