patch 9.0.2134: ml_get error when scrollingv9.0.2134

Problem:  ml_get error when scrolling after delete
Solution: mark topline to be validated in main_loop
          if it is larger than current buffers line
          count

reset_lnums() is called after e.g. TextChanged autocommands and it may
accidentally cause curwin->w_topline to become invalid, e.g. if the
autocommand has deleted some lines.

So verify that curwin->w_topline points to a valid line and if not, mark
the window to have w_topline recalculated in main_loop() in
update_topline() after reset_lnums() returns.

fixes: #13568
fixes: #13578

Signed-off-by: Christian Brabandt <cb@256bit.org>

6 files changed, 875 insertions, 1 deletions

diff --git a/src/testdir/dumps/Test_delete_ml_get_errors_1.dump b/src/testdir/dumps/Test_delete_ml_get_errors_1.dump
new file mode 100644
index 0000000000..9a332a6b9b
--- /dev/null
+++ b/src/testdir/dumps/Test_delete_ml_get_errors_1.dump
@@ -0,0 +1,10 @@
+|-+0&#ffffff0|>| |s|t|d|:@1|o|p|t|i|o|n|a|l|<|D|a|t|a|:@1|W|a|l@1|P|a|p|e|r|>| |{| @39
+@8|i|f| |(|!|_|f|o|r|P|e@1|r|)| |{| @50
+@16|r|e|t|u|r|n| |{|}|;| @48
+@8|}| @65
+@8|c|o|n|s|t| |a|u|t|o| |n|o|n|C|u|s|t|o|m| |=| |W|i|n|d|o|w|:@1|T|h|e|m|e|:@1|B|a|c|k|g|r|o|u|n|d|(|)|-|>|p|a|p|e|r|(|)|;| @6
+@8|c|o|n|s|t| |a|u|t|o| |t|h|e|m|e|E|m|o|j|i| |=| |_|f|o|r|P|e@1|r|-|>|t|h|e|m|e|E|m|o|j|i|(|)|;| @19
+@8|i|f| |(|t|h|e|m|e|E|m|o|j|i|.|i|s|E|m|p|t|y|(|)@1| |{| @39
+|"|s|a|m|p|l|e|s|/|b|o|x|.|t|x|t|"| |6|0|1|L|,| |1|7@1|3@1|B| @44
+|3|5|3| |f|e|w|e|r| |l|i|n|e|s| @59
+|P+0#00e0003&|r|e|s@1| |E|N|T|E|R| |o|r| |t|y|p|e| |c|o|m@1|a|n|d| |t|o| |c|o|n|t|i|n|u|e> +0#0000000&@35
diff --git a/src/testdir/samples/box.txt b/src/testdir/samples/box.txt
new file mode 100644
index 0000000000..21c7d4f3d5
--- /dev/null
+++ b/src/testdir/samples/box.txt
@@ -0,0 +1,601 @@
+void BackgroundBox::prepare() {
+	setTitle(tr::lng_backgrounds_header());
+
+	addButton(tr::lng_close(), [=] { closeBox(); });
+
+	setDimensions(st::boxWideWidth, st::boxMaxListHeight);
+
+	auto wrap = object_ptr<Ui::VerticalLayout>(this);
+	const auto container = wrap.data();
+
+	Settings::AddSkip(container);
+
+	const auto button = container->add(Settings::CreateButton(
+		container,
+		tr::lng_settings_bg_from_file(),
+		st::infoProfileButton));
+	object_ptr<Info::Profile::FloatingIcon>(
+		button,
+		st::infoIconMediaPhoto,
+		st::infoSharedMediaButtonIconPosition);
+
+	button->setClickedCallback([=] {
+		chooseFromFile();
+	});
+
+	Settings::AddSkip(container);
+	Settings::AddDivider(container);
+
+	_inner = container->add(
+		object_ptr<Inner>(this, &_controller->session(), _forPeer));
+
+	container->resizeToWidth(st::boxWideWidth);
+
+	setInnerWidget(std::move(wrap), st::backgroundScroll);
+	setInnerTopSkip(st::lineWidth);
+
+	_inner->chooseEvents(
+	) | rpl::start_with_next([=](const Data::WallPaper &paper) {
+		chosen(paper);
+	}, _inner->lifetime());
+
+	_inner->removeRequests(
+	) | rpl::start_with_next([=](const Data::WallPaper &paper) {
+		removePaper(paper);
+	}, _inner->lifetime());
+}
+
+void BackgroundBox::chooseFromFile() {
+	const auto filterStart = _forPeer
+		? u"Image files (*"_q
+		: u"Theme files (*.tdesktop-theme *.tdesktop-palette *"_q;
+	auto filters = QStringList(
+		filterStart
+		+ Ui::ImageExtensions().join(u" *"_q)
+		+ u")"_q);
+	filters.push_back(FileDialog::AllFilesFilter());
+	const auto callback = [=](const FileDialog::OpenResult &result) {
+		if (result.paths.isEmpty() && result.remoteContent.isEmpty()) {
+			return;
+		}
+
+		if (!_forPeer && !result.paths.isEmpty()) {
+			const auto filePath = result.paths.front();
+			const auto hasExtension = [&](QLatin1String extension) {
+				return filePath.endsWith(extension, Qt::CaseInsensitive);
+			};
+			if (hasExtension(qstr(".tdesktop-theme"))
+				|| hasExtension(qstr(".tdesktop-palette"))) {
+				Window::Theme::Apply(filePath);
+				return;
+			}
+		}
+
+		auto image = Images::Read({
+			.path = result.paths.isEmpty() ? QString() : result.paths.front(),
+			.content = result.remoteContent,
+			.forceOpaque = true,
+		}).image;
+		if (image.isNull() || image.width() <= 0 || image.height() <= 0) {
+			return;
+		}
+		auto local = Data::CustomWallPaper();
+		local.setLocalImageAsThumbnail(std::make_shared<Image>(
+			std::move(image)));
+		_controller->show(Box<BackgroundPreviewBox>(
+			_controller,
+			local,
+			BackgroundPreviewArgs{ _forPeer }));
+	};
+	FileDialog::GetOpenPath(
+		this,
+		tr::lng_choose_image(tr::now),
+		filters.join(u";;"_q),
+		crl::guard(this, callback));
+}
+
+bool BackgroundBox::hasDefaultForPeer() const {
+	Expects(_forPeer != nullptr);
+
+	const auto paper = _forPeer->wallPaper();
+	if (!paper) {
+		return true;
+	}
+	const auto reset = _inner->resolveResetCustomPaper();
+	Assert(reset.has_value());
+	return (paper->id() == reset->id());
+}
+
+bool BackgroundBox::chosenDefaultForPeer(
+		const Data::WallPaper &paper) const {
+	if (!_forPeer) {
+		return false;
+	}
+
+	const auto reset = _inner->resolveResetCustomPaper();
+	Assert(reset.has_value());
+	return (paper.id() == reset->id());
+}
+
+void BackgroundBox::chosen(const Data::WallPaper &paper) {
+	if (chosenDefaultForPeer(paper)) {
+		if (!hasDefaultForPeer()) {
+			const auto reset = crl::guard(this, [=](Fn<void()> close) {
+				resetForPeer();
+				close();
+			});
+			_controller->show(Ui::MakeConfirmBox({
+				.text = tr::lng_background_sure_reset_default(),
+				.confirmed = reset,
+				.confirmText = tr::lng_background_reset_default(),
+			}));
+		} else {
+			closeBox();
+		}
+		return;
+	}
+	_controller->show(Box<BackgroundPreviewBox>(
+		_controller,
+		paper,
+		BackgroundPreviewArgs{ _forPeer }));
+}
+
+void BackgroundBox::resetForPeer() {
+	const auto api = &_controller->session().api();
+	api->request(MTPmessages_SetChatWallPaper(
+		MTP_flags(0),
+		_forPeer->input,
+		MTPInputWallPaper(),
+		MTPWallPaperSettings(),
+		MTPint()
+	)).done([=](const MTPUpdates &result) {
+		api->applyUpdates(result);
+	}).send();
+
+	const auto weak = Ui::MakeWeak(this);
+	_forPeer->setWallPaper(std::nullopt);
+	if (weak) {
+		_controller->finishChatThemeEdit(_forPeer);
+	}
+}
+
+void BackgroundBox::removePaper(const Data::WallPaper &paper) {
+	const auto session = &_controller->session();
+	const auto remove = [=, weak = Ui::MakeWeak(this)](Fn<void()> &&close) {
+		close();
+		if (weak) {
+			weak->_inner->removePaper(paper);
+		}
+		session->data().removeWallpaper(paper);
+		session->api().request(MTPaccount_SaveWallPaper(
+			paper.mtpInput(session),
+			MTP_bool(true),
+			paper.mtpSettings()
+		)).send();
+	};
+	_controller->show(Ui::MakeConfirmBox({
+		.text = tr::lng_background_sure_delete(),
+		.confirmed = remove,
+		.confirmText = tr::lng_selected_delete(),
+	}));
+}
+
+BackgroundBox::Inner::Inner(
+	QWidget *parent,
+	not_null<Main::Session*> session,
+	PeerData *forPeer)
+: RpWidget(parent)
+, _session(session)
+, _forPeer(forPeer)
+, _api(&_session->mtp())
+, _check(std::make_unique<Ui::RoundCheckbox>(st::overviewCheck, [=] { update(); })) {
+	_check->setChecked(true, anim::type::instant);
+	resize(st::boxWideWidth, 2 * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
+	Window::Theme::IsNightModeValue(
+	) | rpl::start_with_next([=] {
+		updatePapers();
+	}, lifetime());
+	requestPapers();
+
+	_session->downloaderTaskFinished(
+	) | rpl::start_with_next([=] {
+		update();
+	}, lifetime());
+
+	style::PaletteChanged(
+	) | rpl::start_with_next([=] {
+		_check->invalidateCache();
+	}, lifetime());
+
+	using Update = Window::Theme::BackgroundUpdate;
+	Window::Theme::Background()->updates(
+	) | rpl::start_with_next([=](const Update &update) {
+		if (update.type == Update::Type::New) {
+			sortPapers();
+			requestPapers();
+			this->update();
+		}
+	}, lifetime());
+
+
+	setMouseTracking(true);
+}
+
+void BackgroundBox::Inner::requestPapers() {
+	_api.request(MTPaccount_GetWallPapers(
+		MTP_long(_session->data().wallpapersHash())
+	)).done([=](const MTPaccount_WallPapers &result) {
+		if (_session->data().updateWallpapers(result)) {
+			updatePapers();
+		}
+	}).send();
+}
+
+auto BackgroundBox::Inner::resolveResetCustomPaper() const
+-> std::optional<Data::WallPaper> {
+	if (!_forPeer) {
+		return {};
+	}
+	const auto nonCustom = Window::Theme::Background()->paper();
+	const auto themeEmoji = _forPeer->themeEmoji();
+	if (themeEmoji.isEmpty()) {
+		return nonCustom;
+	}
+	const auto &themes = _forPeer->owner().cloudThemes();
+	const auto theme = themes.themeForEmoji(themeEmoji);
+	if (!theme) {
+		return nonCustom;
+	}
+	using Type = Data::CloudTheme::Type;  XXXXX
+	const auto dark = Window::Theme::IsNightMode();
+	const auto i = theme->settings.find(dark ? Type::Dark : Type::Light);
+	if (i != end(theme->settings) && i->second.paper) {
+		return *i->second.paper;
+	}
+	return nonCustom;
+}
+
+void BackgroundBox::Inner::pushCustomPapers() {
+	auto customId = uint64();
+	if (const auto custom = _forPeer ? _forPeer->wallPaper() : nullptr) {
+		customId = custom->id();
+		const auto j = ranges::find(
+			_papers,
+			custom->id(),
+			[](const Paper &paper) { return paper.data.id(); });
+		if (j != end(_papers)) {
+			j->data = j->data.withParamsFrom(*custom);
+		} else {
+			_papers.insert(begin(_papers), Paper{ *custom });
+		}
+	}
+	if (const auto reset = resolveResetCustomPaper()) {
+		_insertedResetId = reset->id();
+		const auto j = ranges::find(
+			_papers,
+			_insertedResetId,
+			[](const Paper &paper) { return paper.data.id(); });
+		if (j != end(_papers)) {
+			if (_insertedResetId != customId) {
+				j->data = j->data.withParamsFrom(*reset);
+			}
+		} else {
+			_papers.insert(begin(_papers), Paper{ *reset });
+		}
+	}
+}
+
+void BackgroundBox::Inner::sortPapers() {
+	const auto currentCustom = _forPeer ? _forPeer->wallPaper() : nullptr;
+	_currentId = currentCustom
+		? currentCustom->id()
+		: _insertedResetId
+		? _insertedResetId
+		: Window::Theme::Background()->id();
+	const auto dark = Window::Theme::IsNightMode();
+	ranges::stable_sort(_papers, std::greater<>(), [&](const Paper &paper) {
+		const auto &data = paper.data;
+		return std::make_tuple(
+			_insertedResetId && (_insertedResetId == data.id()),
+			data.id() == _currentId,
+			dark ? data.isDark() : !data.isDark(),
+			Data::IsDefaultWallPaper(data),
+			!data.isDefault() && !Data::IsLegacy1DefaultWallPaper(data),
+			Data::IsLegacy3DefaultWallPaper(data),
+			Data::IsLegacy2DefaultWallPaper(data),
+			Data::IsLegacy1DefaultWallPaper(data));
+	});
+	if (!_papers.empty()
+		&& _papers.front().data.id() == _currentId
+		&& !currentCustom
+		&& !_insertedResetId) {
+		_papers.front().data = _papers.front().data.withParamsFrom(
+			Window::Theme::Background()->paper());
+	}
+}
+
+void BackgroundBox::Inner::updatePapers() {
+	if (_session->data().wallpapers().empty()) {
+		return;
+	}
+	_over = _overDown = Selection();
+
+	_papers = _session->data().wallpapers(
+	) | ranges::views::filter([&](const Data::WallPaper &paper) {
+		return (!paper.isPattern() || !paper.backgroundColors().empty())
+			&& (!_forPeer
+				|| (!Data::IsDefaultWallPaper(paper)
+					&& (Data::IsCloudWallPaper(paper)
+						|| Data::IsCustomWallPaper(paper))));
+	}) | ranges::views::transform([](const Data::WallPaper &paper) {
+		return Paper{ paper };
+	}) | ranges::to_vector;
+	pushCustomPapers();
+	sortPapers();
+	resizeToContentAndPreload();
+}
+
+void BackgroundBox::Inner::resizeToContentAndPreload() {
+	const auto count = _papers.size();
+	const auto rows = (count / kBackgroundsInRow)
+		+ (count % kBackgroundsInRow ? 1 : 0);
+
+	resize(
+		st::boxWideWidth,
+		(rows * (st::backgroundSize.height() + st::backgroundPadding)
+			+ st::backgroundPadding));
+
+	const auto preload = kBackgroundsInRow * 3;
+	for (const auto &paper : _papers | ranges::views::take(preload)) {
+		if (!paper.data.localThumbnail() && !paper.dataMedia) {
+			if (const auto document = paper.data.document()) {
+				paper.dataMedia = document->createMediaView();
+				paper.dataMedia->thumbnailWanted(paper.data.fileOrigin());
+			}
+		}
+	}
+	update();
+}
+
+void BackgroundBox::Inner::paintEvent(QPaintEvent *e) {
+	QRect r(e->rect());
+	auto p = QPainter(this);
+
+	if (_papers.empty()) {
+		p.setFont(st::noContactsFont);
+		p.setPen(st::noContactsColor);
+		p.drawText(QRect(0, 0, width(), st::noContactsHeight), tr::lng_contacts_loading(tr::now), style::al_center);
+		return;
+	}
+	auto row = 0;
+	auto column = 0;
+	for (const auto &paper : _papers) {
+		const auto increment = gsl::finally([&] {
+			++column;
+			if (column == kBackgroundsInRow) {
+				column = 0;
+				++row;
+			}
+		});
+		if ((st::backgroundSize.height() + st::backgroundPadding) * (row + 1) <= r.top()) {
+			continue;
+		} else if ((st::backgroundSize.height() + st::backgroundPadding) * row >= r.top() + r.height()) {
+			break;
+		}
+		paintPaper(p, paper, column, row);
+	}
+}
+
+void BackgroundBox::Inner::validatePaperThumbnail(
+		const Paper &paper) const {
+	if (!paper.thumbnail.isNull()) {
+		return;
+	}
+	const auto localThumbnail = paper.data.localThumbnail();
+	if (!localThumbnail) {
+		if (const auto document = paper.data.document()) {
+			if (!paper.dataMedia) {
+				paper.dataMedia = document->createMediaView();
+				paper.dataMedia->thumbnailWanted(paper.data.fileOrigin());
+			}
+			if (!paper.dataMedia->thumbnail()) {
+				return;
+			}
+		} else if (!paper.data.backgroundColors().empty()) {
+			paper.thumbnail = Ui::PixmapFromImage(
+				Ui::GenerateBackgroundImage(
+					st::backgroundSize * cIntRetinaFactor(),
+					paper.data.backgroundColors(),
+					paper.data.gradientRotation()));
+			paper.thumbnail.setDevicePixelRatio(cRetinaFactor());
+			return;
+		} else {
+			return;
+		}
+	}
+	const auto thumbnail = localThumbnail
+		? localThumbnail
+		: paper.dataMedia->thumbnail();
+	auto original = thumbnail->original();
+	if (paper.data.isPattern()) {
+		original = Ui::PreparePatternImage(
+			std::move(original),
+			paper.data.backgroundColors(),
+			paper.data.gradientRotation(),
+			paper.data.patternOpacity());
+	}
+	paper.thumbnail = Ui::PixmapFromImage(TakeMiddleSample(
+		original,
+		st::backgroundSize));
+	paper.thumbnail.setDevicePixelRatio(cRetinaFactor());
+}
+
+void BackgroundBox::Inner::paintPaper(
+		QPainter &p,
+		const Paper &paper,
+		int column,
+		int row) const {
+	const auto x = st::backgroundPadding + column * (st::backgroundSize.width() + st::backgroundPadding);
+	const auto y = st::backgroundPadding + row * (st::backgroundSize.height() + st::backgroundPadding);
+	validatePaperThumbnail(paper);
+	if (!paper.thumbnail.isNull()) {
+		p.drawPixmap(x, y, paper.thumbnail);
+	}
+
+	const auto over = !v::is_null(_overDown) ? _overDown : _over;
+	if (paper.data.id() == _currentId) {
+		const auto checkLeft = x + st::backgroundSize.width() - st::overviewCheckSkip - st::overviewCheck.size;
+		const auto checkTop = y + st::backgroundSize.height() - st::overviewCheckSkip - st::overviewCheck.size;
+		_check->paint(p, checkLeft, checkTop, width());
+	} else if (Data::IsCloudWallPaper(paper.data)
+		&& !Data::IsDefaultWallPaper(paper.data)
+		&& !Data::IsLegacy2DefaultWallPaper(paper.data)
+		&& !Data::IsLegacy3DefaultWallPaper(paper.data)
+		&& !v::is_null(over)
+		&& (&paper == &_papers[getSelectionIndex(over)])) {
+		const auto deleteSelected = v::is<DeleteSelected>(over);
+		const auto deletePos = QPoint(x + st::backgroundSize.width() - st::stickerPanDeleteIconBg.width(), y);
+		p.setOpacity(deleteSelected ? st::stickerPanDeleteOpacityBgOver : st::stickerPanDeleteOpacityBg);
+		st::stickerPanDeleteIconBg.paint(p, deletePos, width());
+		p.setOpacity(deleteSelected ? st::stickerPanDeleteOpacityFgOver : st::stickerPanDeleteOpacityFg);
+		st::stickerPanDeleteIconFg.paint(p, deletePos, width());
+		p.setOpacity(1.);
+	}
+}
+
+void BackgroundBox::Inner::mouseMoveEvent(QMouseEvent *e) {
+	const auto newOver = [&] {
+		const auto x = e->pos().x();
+		const auto y = e->pos().y();
+		const auto width = st::backgroundSize.width();
+		const auto height = st::backgroundSize.height();
+		const auto skip = st::backgroundPadding;
+		const auto row = int((y - skip) / (height + skip));
+		const auto column = int((x - skip) / (width + skip));
+		const auto result = row * kBackgroundsInRow + column;
+		if (y - row * (height + skip) > skip + height) {
+			return Selection();
+		} else if (x - column * (width + skip) > skip + width) {
+			return Selection();
+		} else if (result >= _papers.size()) {
+			return Selection();
+		}
+		auto &data = _papers[result].data;
+		const auto deleteLeft = (column + 1) * (width + skip)
+			- st::stickerPanDeleteIconBg.width();
+		const auto deleteBottom = row * (height + skip) + skip
+			+ st::stickerPanDeleteIconBg.height();
+		const auto inDelete = (x >= deleteLeft)
+			&& (y < deleteBottom)
+			&& Data::IsCloudWallPaper(data)
+			&& !Data::IsDefaultWallPaper(data)
+			&& !Data::IsLegacy2DefaultWallPaper(data)
+			&& !Data::IsLegacy3DefaultWallPaper(data)
+			&& (_currentId != data.id());
+		return (result >= _papers.size())
+			? Selection()
+			: inDelete
+			? Selection(DeleteSelected{ result })
+			: Selection(Selected{ result });
+	}();
+	if (_over != newOver) {
+		repaintPaper(getSelectionIndex(_over));
+		_over = newOver;
+		repaintPaper(getSelectionIndex(_over));
+		setCursor((!v::is_null(_over) || !v::is_null(_overDown))
+			? style::cur_pointer
+			: style::cur_default);
+	}
+}
+
+void BackgroundBox::Inner::repaintPaper(int index) {
+	if (index < 0 || index >= _papers.size()) {
+		return;
+	}
+	const auto row = (index / kBackgroundsInRow);
+	const auto column = (index % kBackgroundsInRow);
+	const auto width = st::backgroundSize.width();
+	const auto height = st::backgroundSize.height();
+	const auto skip = st::backgroundPadding;
+	update(
+		(width + skip) * column + skip,
+		(height + skip) * row + skip,
+		width,
+		height);
+}
+
+void BackgroundBox::Inner::mousePressEvent(QMouseEvent *e) {
+	_overDown = _over;
+}
+
+int BackgroundBox::Inner::getSelectionIndex(
+		const Selection &selection) const {
+	return v::match(selection, [](const Selected &data) {
+		return data.index;
+	}, [](const DeleteSelected &data) {
+		return data.index;
+	}, [](v::null_t) {
+		return -1;
+	});
+}
+
+void BackgroundBox::Inner::mouseReleaseEvent(QMouseEvent *e) {
+	if (base::take(_overDown) == _over && !v::is_null(_over)) {
+		const auto index = getSelectionIndex(_over);
+		if (index >= 0 && index < _papers.size()) {
+			if (std::get_if<DeleteSelected>(&_over)) {
+				_backgroundRemove.fire_copy(_papers[index].data);
+			} else if (std::get_if<Selected>(&_over)) {
+				auto &paper = _papers[index];
+				if (!paper.dataMedia) {
+					if (const auto document = paper.data.document()) {
+						// Keep it alive while it is on the screen.
+						paper.dataMedia = document->createMediaView();
+					}
+				}
+				_backgroundChosen.fire_copy(paper.data);
+			}
+		}
+	} else if (v::is_null(_over)) {
+		setCursor(style::cur_default);
+	}
+}
+
+void BackgroundBox::Inner::visibleTopBottomUpdated(
+		int visibleTop,
+		int visibleBottom) {
+	for (auto i = 0, count = int(_papers.size()); i != count; ++i) {
+		const auto row = (i / kBackgroundsInRow);
+		const auto height = st::backgroundSize.height();
+		const auto skip = st::backgroundPadding;
+		const auto top = skip + row * (height + skip);
+		const auto bottom = top + height;
+		if ((bottom <= visibleTop || top >= visibleBottom)
+			&& !_papers[i].thumbnail.isNull()) {
+			_papers[i].dataMedia = nullptr;
+		}
+	}
+}
+
+rpl::producer<Data::WallPaper> BackgroundBox::Inner::chooseEvents() const {
+	return _backgroundChosen.events();
+}
+
+auto BackgroundBox::Inner::removeRequests() const
+-> rpl::producer<Data::WallPaper> {
+	return _backgroundRemove.events();
+}
+
+void BackgroundBox::Inner::removePaper(const Data::WallPaper &data) {
+	const auto i = ranges::find(
+		_papers,
+		data.id(),
+		[](const Paper &paper) { return paper.data.id(); });
+	if (i != end(_papers)) {
+		_papers.erase(i);
+		_over = _overDown = Selection();
+		resizeToContentAndPreload();
+	}
+}
+
+BackgroundBox::Inner::~Inner() = default;
diff --git a/src/testdir/samples/matchparen.vim b/src/testdir/samples/matchparen.vim
new file mode 100644
index 0000000000..4235a0d39b
--- /dev/null
+++ b/src/testdir/samples/matchparen.vim
@@ -0,0 +1,234 @@
+" Vim plugin for showing matching parens
+" Maintainer:	The Vim Project <https://github.com/vim/vim>
+" Last Change:	2023 Oct 20
+" Former Maintainer:	Bram Moolenaar <Bram@vim.org>
+
+" Exit quickly when:
+" - this plugin was already loaded (or disabled)
+" - when 'compatible' is set
+if exists("g:loaded_matchparen") || &cp
+  finish
+endif
+let g:loaded_matchparen = 1
+
+if !exists("g:matchparen_timeout")
+  let g:matchparen_timeout = 300
+endif
+if !exists("g:matchparen_insert_timeout")
+  let g:matchparen_insert_timeout = 60
+endif
+
+let s:has_matchaddpos = exists('*matchaddpos')
+
+augroup matchparen
+  " Replace all matchparen autocommands
+  autocmd! CursorMoved,CursorMovedI,WinEnter,BufWinEnter,WinScrolled * call s:Highlight_Matching_Pair()
+  autocmd! WinLeave,BufLeave * call s:Remove_Matches()
+  if exists('##TextChanged')
+    autocmd! TextChanged,TextChangedI * call s:Highlight_Matching_Pair()
+    autocmd! TextChangedP * call s:Remove_Matches()
+  endif
+augroup END
+
+" Skip the rest if it was already done.
+if exists("*s:Highlight_Matching_Pair")
+  finish
+endif
+
+let s:cpo_save = &cpo
+set cpo-=C
+
+" The function that is invoked (very often) to define a ":match" highlighting
+" for any matching paren.
+func s:Highlight_Matching_Pair()
+  if !exists("w:matchparen_ids")
+    let w:matchparen_ids = []
+  endif
+  " Remove any previous match.
+  call s:Remove_Matches()
+
+  " Avoid that we remove the popup menu.
+  " Return when there are no colors (looks like the cursor jumps).
+  if pumvisible() || (&t_Co < 8 && !has("gui_running"))
+    return
+  endif
+
+  " Get the character under the cursor and check if it's in 'matchpairs'.
+  let c_lnum = line('.')
+  let c_col = col('.')
+  let before = 0
+
+  let text = getline(c_lnum)
+  let matches = matchlist(text, '\(.\)\=\%'.c_col.'c\(.\=\)')
+  if empty(matches)
+    let [c_before, c] = ['', '']
+  else
+    let [c_before, c] = matches[1:2]
+  endif
+  let plist = split(&matchpairs, '.\zs[:,]')
+  let i = index(plist, c)
+  if i < 0
+    " not found, in Insert mode try character before the cursor
+    if c_col > 1 && (mode() == 'i' || mode() == 'R')
+      let before = strlen(c_before)
+      let c = c_before
+      let i = index(plist, c)
+    endif
+    if i < 0
+      " not found, nothing to do
+      return
+    endif
+  endif
+
+  " Figure out the arguments for searchpairpos().
+  if i % 2 == 0
+    let s_flags = 'nW'
+    let c2 = plist[i + 1]
+  else
+    let s_flags = 'nbW'
+    let c2 = c
+    let c = plist[i - 1]
+  endif
+  if c == '['
+    let c = '\['
+    let c2 = '\]'
+  endif
+
+  " Find the match.  When it was just before the cursor move it there for a
+  " moment.
+  if before > 0
+    let has_getcurpos = exists("*getcurpos")
+    if has_getcurpos
+      " getcurpos() is more efficient but doesn't exist before 7.4.313.
+      let save_cursor = getcurpos()
+    else
+      let save_cursor = winsaveview()
+    endif
+    call cursor(c_lnum, c_col - before)
+  endif
+
+  if !has("syntax") || !exists("g:syntax_on")
+    let s_skip = "0"
+  else
+    " Build an expression that detects whether the current cursor position is
+    " in certain syntax types (string, comment, etc.), for use as
+    " searchpairpos()'s skip argument.
+    " We match "escape" for special items, such as lispEscapeSpecial, and
+    " match "symbol" for lispBarSymbol.
+    let s_skip = 'synstack(".", col("."))'
+        \ . '->indexof({_, id -> synIDattr(id, "name") =~? '
+        \ . '"string\\|character\\|singlequote\\|escape\\|symbol\\|comment"}) >= 0'
+    " If executing the expression determines that the cursor is currently in
+    " one of the syntax types, then we want searchpairpos() to find the pair
+    " within those syntax types (i.e., not skip).  Otherwise, the cursor is
+    " outside of the syntax types and s_skip should keep its value so we skip
+    " any matching pair inside the syntax types.
+    " Catch if this throws E363: pattern uses more memory than 'maxmempattern'.
+    try
+      execute 'if ' . s_skip . ' | let s_skip = "0" | endif'
+    catch /^Vim\%((\a\+)\)\=:E363/
+      " We won't find anything, so skip searching, should keep Vim responsive.
+      return
+    endtry
+  endif
+
+  " Limit the search to lines visible in the window.
+  let stoplinebottom = line('w$')
+  let stoplinetop = line('w0')
+  if i % 2 == 0
+    let stopline = stoplinebottom
+  else
+    let stopline = stoplinetop
+  endif
+
+  " Limit the search time to 300 msec to avoid a hang on very long lines.
+  " This fails when a timeout is not supported.
+  if mode() == 'i' || mode() == 'R'
+    let timeout = exists("b:matchparen_insert_timeout") ? b:matchparen_insert_timeout : g:matchparen_insert_timeout
+  else
+    let timeout = exists("b:matchparen_timeout") ? b:matchparen_timeout : g:matchparen_timeout
+  endif
+  try
+    let [m_lnum, m_col] = searchpairpos(c, '', c2, s_flags, s_skip, stopline, timeout)
+  catch /E118/
+    " Can't use the timeout, restrict the stopline a bit more to avoid taking
+    " a long time on closed folds and long lines.
+    " The "viewable" variables give a range in which we can scroll while
+    " keeping the cursor at the same position.
+    " adjustedScrolloff accounts for very large numbers of scrolloff.
+    let adjustedScrolloff = min([&scrolloff, (line('w$') - line('w0')) / 2])
+    let bottom_viewable = min([line('$'), c_lnum + &lines - adjustedScrolloff - 2])
+    let top_viewable = max([1, c_lnum-&lines+adjustedScrolloff + 2])
+    " one of these stoplines will be adjusted below, but the current values are
+    " minimal boundaries within the current window
+    if i % 2 == 0
+      if has("byte_offset") && has("syntax_items") && &smc > 0
+	let stopbyte = min([line2byte("$"), line2byte(".") + col(".") + &smc * 2])
+	let stopline = min([bottom_viewable, byte2line(stopbyte)])
+      else
+	let stopline = min([bottom_viewable, c_lnum + 100])
+      endif
+      let stoplinebottom = stopline
+    else
+      if has("byte_offset") && has("syntax_items") && &smc > 0
+	let stopbyte = max([1, line2byte(".") + col(".") - &smc * 2])
+	let stopline = max([top_viewable, byte2line(stopbyte)])
+      else
+	let stopline = max([top_viewable, c_lnum - 100])
+      endif
+      let stoplinetop = stopline
+    endif
+    let [m_lnum, m_col] = searchpairpos(c, '', c2, s_flags, s_skip, stopline)
+  endtry
+
+  if before > 0
+    if has_getcurpos
+      call setpos('.', save_cursor)
+    else
+      call winrestview(save_cursor)
+    endif
+  endif
+
+  " If a match is found setup match highlighting.
+  if m_lnum > 0 && m_lnum >= stoplinetop && m_lnum <= stoplinebottom 
+    if s:has_matchaddpos
+      call add(w:matchparen_ids, matchaddpos('MatchParen', [[c_lnum, c_col - before], [m_lnum, m_col]], 10))
+    else
+      exe '3match MatchParen /\(\%' . c_lnum . 'l\%' . (c_col - before) .
+	    \ 'c\)\|\(\%' . m_lnum . 'l\%' . m_col . 'c\)/'
+      call add(w:matchparen_ids, 3)
+    endif
+    let w:paren_hl_on = 1
+  endif
+endfunction
+
+func s:Remove_Matches()
+  if exists('w:paren_hl_on') && w:paren_hl_on
+    while !empty(w:matchparen_ids)
+      silent! call remove(w:matchparen_ids, 0)->matchdelete()
+    endwhile
+    let w:paren_hl_on = 0
+  endif
+endfunc
+
+" Define commands that will disable and enable the plugin.
+command DoMatchParen call s:DoMatchParen()
+command NoMatchParen call s:NoMatchParen()
+
+func s:NoMatchParen()
+  let w = winnr()
+  noau windo silent! call matchdelete(3)
+  unlet! g:loaded_matchparen
+  exe "noau ". w . "wincmd w"
+  au! matchparen
+endfunc
+
+func s:DoMatchParen()
+  runtime plugin/matchparen.vim
+  let w = winnr()
+  silent windo doau CursorMoved
+  exe "noau ". w . "wincmd w"
+endfunc
+
+let &cpo = s:cpo_save
+unlet s:cpo_save
diff --git a/src/testdir/test_delete.vim b/src/testdir/test_delete.vim
index b05c27d626..c00b8ca47d 100644
--- a/src/testdir/test_delete.vim
+++ b/src/testdir/test_delete.vim
@@ -1,6 +1,8 @@
 " Test for delete().
 
 source check.vim
+source term_util.vim
+source screendump.vim
 
 func Test_file_delete()
   split Xfdelfile
@@ -107,4 +109,25 @@ func Test_delete_errors()
   call assert_fails('call delete(''foo'', 0)', 'E15:')
 endfunc
 
+" This should no longer trigger ml_get errors
+func Test_delete_ml_get_errors()
+  CheckRunVimInTerminal
+  let lines =<< trim END
+    set noshowcmd noruler scrolloff=0
+    source samples/matchparen.vim
+  END
+  call writefile(lines, 'XDelete_ml_get_error', 'D')
+  let buf = RunVimInTerminal('-S XDelete_ml_get_error samples/box.txt', #{rows: 10, wait_for_ruler: 0})
+  call TermWait(buf)
+  call term_sendkeys(buf, "249GV\<C-End>d")
+  call TermWait(buf)
+  " The following used to trigger ml_get errors
+  call term_sendkeys(buf, "\<PageUp>")
+  call TermWait(buf)
+  call term_sendkeys(buf, ":mess\<cr>")
+  call VerifyScreenDump(buf, 'Test_delete_ml_get_errors_1', {})
+  call term_sendkeys(buf, ":q!\<cr>")
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 4a7cf7d392..ae536261ef 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2134,
+/**/
     2133,
 /**/
     2132,
diff --git a/src/window.c b/src/window.c
index 55ce31c886..0f4363b942 100644
--- a/src/window.c
+++ b/src/window.c
@@ -7441,12 +7441,16 @@ reset_lnums(void)
 	{
 	    // Restore the value if the autocommand didn't change it and it was
 	    // set.
+	    // Note: This triggers e.g. on BufReadPre, when the buffer is not yet
+	    //       loaded, so cannot validate the buffer line
 	    if (EQUAL_POS(wp->w_save_cursor.w_cursor_corr, wp->w_cursor)
 				  && wp->w_save_cursor.w_cursor_save.lnum != 0)
 		wp->w_cursor = wp->w_save_cursor.w_cursor_save;
 	    if (wp->w_save_cursor.w_topline_corr == wp->w_topline
-				      && wp->w_save_cursor.w_topline_save != 0)
+				  && wp->w_save_cursor.w_topline_save != 0)
 		wp->w_topline = wp->w_save_cursor.w_topline_save;
+	   if (wp->w_save_cursor.w_topline_save > wp->w_buffer->b_ml.ml_line_count)
+		wp->w_valid &= ~VALID_TOPLINE;
 	}
 }