From 5e0f46583b313efe53f66d7c236f871dc7cb0a53 Mon Sep 17 00:00:00 2001
From: Silvio <silvio.traversaro@iit.it>
Date: Fri, 26 Jul 2024 11:00:05 +0200
Subject: [PATCH 1/2] Fix sending empty yarp::sig::Vector in Debug build type

---
 src/libYARP_sig/src/yarp/sig/Vector.cpp | 12 +++++---
 src/libYARP_sig/tests/VectorOfTest.cpp  | 37 ++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/src/libYARP_sig/src/yarp/sig/Vector.cpp b/src/libYARP_sig/src/yarp/sig/Vector.cpp
index 2e190931e7f..6add16bc639 100644
--- a/src/libYARP_sig/src/yarp/sig/Vector.cpp
+++ b/src/libYARP_sig/src/yarp/sig/Vector.cpp
@@ -84,11 +84,15 @@ bool VectorBase::write(yarp::os::ConnectionWriter& connection) const {
     header.listLen = (int)getListSize();
 
     connection.appendBlock((char*)&header, sizeof(header));
-    const char *ptr = getMemoryBlock();
-    int elemSize=getElementSize();
-    yCAssert(VECTOR, ptr != nullptr);
 
-    connection.appendExternalBlock(ptr, elemSize*header.listLen);
+    if (header.listLen > 0)
+    {
+        const char *ptr = getMemoryBlock();
+        int elemSize=getElementSize();
+        yCAssert(VECTOR, ptr != nullptr);
+
+        connection.appendExternalBlock(ptr, elemSize*header.listLen);
+    }
 
     // if someone is foolish enough to connect in text mode,
     // let them see something readable.
diff --git a/src/libYARP_sig/tests/VectorOfTest.cpp b/src/libYARP_sig/tests/VectorOfTest.cpp
index 35f30a484ad..643c7d7ca85 100644
--- a/src/libYARP_sig/tests/VectorOfTest.cpp
+++ b/src/libYARP_sig/tests/VectorOfTest.cpp
@@ -31,7 +31,6 @@ TEST_CASE("sig::VectorOfTest", "[yarp::sig]")
     SECTION("Check send and receive integers")
     {
         INFO("check VectorO<int> send receive");
-
         {
             Port portIn;
             Port portOut;
@@ -79,6 +78,42 @@ TEST_CASE("sig::VectorOfTest", "[yarp::sig]")
             portIn.close();
         }
 
+        INFO("check VectorOf<int> send empty vector");
+        {
+            Port portIn;
+            Port portOut;
+
+            portOut.open("/harness_sig/vtest/empty_vector/o");
+            portIn.open("/harness_sig/vtest/empty_vector/i");
+
+            Network::connect("/harness_sig/vtest/empty_vector/o", "/harness_sig/vtest/empty_vector/i");
+
+            portOut.enableBackgroundWrite(true);
+
+
+            VectorOf<int> vector;
+            vector.resize(0);
+
+            bool success = true;
+            portOut.write(vector);
+
+            VectorOf<int> tmp;
+            portIn.read(tmp);
+
+            //compare vector and tmp
+            if (tmp.size() != vector.size())
+            {
+                success = false;
+            }
+
+            CHECK(success); // empty VectorOf<int> was sent and received correctly
+
+            portOut.interrupt();
+            portOut.close();
+            portIn.interrupt();
+            portIn.close();
+        }
+
         INFO("check VectorOf<int> bottle compatibility");
         {
             //write the same vector again and receive it as a bottle

From 39b4fef6505d225603abd91ef149f245784bbc02 Mon Sep 17 00:00:00 2001
From: Silvio Traversaro <silvio@traversaro.it>
Date: Fri, 26 Jul 2024 11:39:03 +0200
Subject: [PATCH 2/2] Update release notes

---
 doc/release/master.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/release/master.md b/doc/release/master.md
index a2a4e6d3661..4eb546ff369 100644
--- a/doc/release/master.md
+++ b/doc/release/master.md
@@ -32,6 +32,7 @@ Fixes
 * `yarpbatterygui` now compatible with battery_nwc_yarp.
 * Fixed compilation of portmonitor carrier when a custom non-system swig is used
 * Fixed compatibility with ffmpeg 7 (https://github.com/robotology/yarp/pull/3109).
+* Fix sending empty yarp::sig::Vector when building in Debug (https://github.com/robotology/yarp/pull/3123).
 
 New Features
 ------------