Fix crash on redraw in BufCloseFifo hook

FifoWatcher::read_fifo() deletes the fifo watcher in

	m_buffer.values().erase(fifo_watcher_id); // will delete this

which calls:           HashMap::unordered_remove()
                           constexpr_swap(m_items[index], m_items.back());
destructor called here --> m_items.pop_back();
                           m_index.remove(hash, index);

So hash map invariants (of buffer.values()) are broken, when calling
~FifoWatcher which fires BufCloseFifo hooks. Things blow up if those
hooks access buffer.values() such as by accessing cached highlighters
to redraw the buffer.  A shell call with a long sleep in the client
context seems to trigger this.

Fix this by destroying removed map items only at the end of
HashMap::remove(), when invariants are restored.  Alternatively, we
could introduce a fifo_trash container; I haven't explored that.

4 files changed, 20 insertions, 0 deletions

diff --git a/test/regression/0-slow-BufCloseFifo/cmd b/test/regression/0-slow-BufCloseFifo/cmd
new file mode 100644
index 00000000..2eeea72e
--- /dev/null
+++ b/test/regression/0-slow-BufCloseFifo/cmd
@@ -0,0 +1 @@
+:run<ret>
diff --git a/test/regression/0-slow-BufCloseFifo/in b/test/regression/0-slow-BufCloseFifo/in
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/test/regression/0-slow-BufCloseFifo/in
@@ -0,0 +1 @@
+
diff --git a/test/regression/0-slow-BufCloseFifo/rc b/test/regression/0-slow-BufCloseFifo/rc
new file mode 100644
index 00000000..8a953e18
--- /dev/null
+++ b/test/regression/0-slow-BufCloseFifo/rc
@@ -0,0 +1,16 @@
+define-command run %{
+    evaluate-commands %sh{
+        mkfifo fifo1 fifo2 2>/dev/null
+        ( : >fifo1 & ) > /dev/null 2>&1 </dev/null
+    }
+    edit! -fifo fifo1 *fifo*
+    add-highlighter global/myhl regex foo 0:green
+    hook -once global BufCloseFifo .* %{
+        evaluate-commands -client client0 %{
+            nop %sh{sleep 2}
+        }
+        hook -once buffer NormalIdle .* %{
+            echo -to-file fifo2 still alive
+        }
+    }
+}
diff --git a/test/regression/0-slow-BufCloseFifo/script b/test/regression/0-slow-BufCloseFifo/script
new file mode 100644
index 00000000..2147a8e8
--- /dev/null
+++ b/test/regression/0-slow-BufCloseFifo/script
@@ -0,0 +1,2 @@
+mkfifo fifo2 2>/dev/null
+assert_eq "$(cat fifo2)" "still alive"