From a69b0c80324b2a26bab6bd36fd941359ddeabf7b Mon Sep 17 00:00:00 2001
From: "Dustin J. Mitchell" <djmitche@google.com>
Date: Sun, 28 May 2023 21:13:01 +0000
Subject: [PATCH] Remove properties when set to an empty string

Fixes #3109.
---
 src/TDB2.cpp   |  7 ++++++-
 test/tw-3109.t | 11 +++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 test/tw-3109.t

diff --git a/src/TDB2.cpp b/src/TDB2.cpp
index 90e9202ba..4411475f5 100644
--- a/src/TDB2.cpp
+++ b/src/TDB2.cpp
@@ -169,7 +169,12 @@ void TDB2::modify (Task& task)
       update = true;
     }
     if (update) {
-      tctask.set_value(k, make_optional (v_new));
+      // An empty string indicates the value should be removed.
+      if (v_new == "") {
+        tctask.set_value(k, {});
+      } else {
+        tctask.set_value(k, make_optional (v_new));
+      }
     }
   }
 
diff --git a/test/tw-3109.t b/test/tw-3109.t
new file mode 100644
index 000000000..5375c91ba
--- /dev/null
+++ b/test/tw-3109.t
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+. bash_tap_tw.sh
+
+task add emptyval
+task 1 done
+task 1 mod end: status:pending
+task_end=`task 1 info | grep ^End | sed -e 's/^End //' || true`
+echo "task_end: $task_end"
+
+# `task mod end:` should have deleted the end.
+[[ "$task_end" == "" ]]