Ensure buffer create/close hooks are run at appropriate times

They used to be ran before the buffer was added to the buffer list
we now run them afterwards.

src/buffer.cc

@@ -69,8 +69,6 @@ Buffer::Buffer(String name, Flags flags, StringView data,
       m_last_save_undo_index(0),
       m_fs_timestamp(fs_timestamp)
 {
-    options().register_watcher(*this);
-
     ParsedLines parsed_lines = parse_lines(data);
 
     if (parsed_lines.lines.empty())
@@ -87,9 +85,24 @@ Buffer::Buffer(String name, Flags flags, StringView data,
 
     apply_options(options(), parsed_lines);
 
-    if (flags & Flags::File)
+    // now we may begin to record undo data
+    if (not (flags & Flags::NoUndo))
+        m_flags &= ~Flags::NoUndo;
+}
+
+void Buffer::on_registered()
 {
-        if (flags & Flags::New)
+    // Ignore debug buffer, as it can be created in many
+    // corner cases (including while destroying the BufferManager
+    // if a BufClose hooks triggers writing to it.
+    if (m_flags & Flags::Debug)
+        return;
+
+    options().register_watcher(*this);
+
+    if (m_flags & Flags::File)
+    {
+        if (m_flags & Buffer::Flags::New)
             run_hook_in_own_context("BufNew", m_name);
         else
         {
@@ -100,19 +113,21 @@ Buffer::Buffer(String name, Flags flags, StringView data,
 
     run_hook_in_own_context("BufCreate", m_name);
 
-    // now we may begin to record undo data
-    if (not (flags & Flags::NoUndo))
-        m_flags &= ~Flags::NoUndo;
-
     for (auto& option : options().flatten_options())
         on_option_changed(*option);
 }
 
-Buffer::~Buffer()
+void Buffer::on_unregistered()
 {
-    run_hook_in_own_context("BufClose", m_name);
+    if (m_flags & Flags::Debug)
+        return;
 
     options().unregister_watcher(*this);
+    run_hook_in_own_context("BufClose", m_name);
+}
+
+Buffer::~Buffer()
+{
     m_values.clear();
 }
 

src/buffer.hh

@@ -200,6 +200,10 @@ public:
     ConstArrayView<Change> changes_since(size_t timestamp) const;
 
     String debug_description() const;
+
+    // Methods called by the buffer manager
+    void on_registered();
+    void on_unregistered();
 private:
 
     void on_option_changed(const Option& option) override;

src/buffer_manager.cc

@@ -22,6 +22,9 @@ BufferManager::~BufferManager()
     // hook while clearing m_buffers
     m_buffer_trash = std::move(m_buffers);
 
+    for (auto& buffer : m_buffer_trash)
+        buffer->on_unregistered();
+
     // Make sure not clients exists
     ClientManager::instance().clear();
 }
@@ -37,9 +40,12 @@ Buffer* BufferManager::create_buffer(String name, Buffer::Flags flags,
             throw name_not_unique();
     }
 
-    m_buffers.emplace(m_buffers.begin(), new Buffer{std::move(name), flags,
-                                                    data, fs_timestamp});
-    return m_buffers.front().get();
+    m_buffers.emplace(m_buffers.begin(),
+                      new Buffer{std::move(name), flags, data, fs_timestamp});
+    auto& buffer = *m_buffers.front();
+    buffer.on_registered();
+
+    return &buffer;
 }
 
 void BufferManager::delete_buffer(Buffer& buffer)
@@ -48,10 +54,13 @@ void BufferManager::delete_buffer(Buffer& buffer)
                       { return p.get() == &buffer; });
     kak_assert(it != m_buffers.end());
 
+
     ClientManager::instance().ensure_no_client_uses_buffer(buffer);
 
     m_buffer_trash.emplace_back(std::move(*it));
     m_buffers.erase(it);
+
+    buffer.on_unregistered();
 }
 
 Buffer* BufferManager::get_buffer_ifp(StringView name)

src/main.cc

@@ -664,11 +664,11 @@ int run_filter(StringView keystr, StringView commands, ConstArrayView<StringView
         }
         if (not isatty(0))
         {
-            Buffer* buffer = buffer_manager.create_buffer(
+            Buffer& buffer = *buffer_manager.create_buffer(
                 "*stdin*", Buffer::Flags::None, read_fd(0), InvalidTime);
-            apply_to_buffer(*buffer);
-            write_buffer_to_fd(*buffer, 1);
-            buffer_manager.delete_buffer(*buffer);
+            apply_to_buffer(buffer);
+            write_buffer_to_fd(buffer, 1);
+            buffer_manager.delete_buffer(buffer);
         }
     }
     catch (Kakoune::runtime_error& err)