Merge bitcoin/bitcoin#24132: build: Bump minimum Qt version to 5.11.3

956f7322f60db7b8be551c9074b4c633e514079d build: Bump minimum Qt version to 5.11.3 (Hennadii Stepanov)
e22d10b936eb7563b2b6611332d9e4c73a2f59d4 ci: Switch from bionic to buster (Hennadii Stepanov)

Pull request description:

  The current minimum Qt version is 5.9.5 which has been set in bitcoin/bitcoin#21286.

  Distro support:
  - centos 7 -- unsupported since bitcoin/bitcoin#23511
  - centos 8 -- [5.15.2](http://mirror.centos.org/centos/8/AppStream/x86_64/os/Packages/qt5-qtbase-5.15.2-3.el8.x86_64.rpm)
  - buster -- [5.11.3](https://packages.debian.org/buster/libqt5core5a)
  - bullseye  -- [5.15.2](https://packages.debian.org/bullseye/libqt5core5a)
  - _bionic_ -- [5.9.5](https://packages.ubuntu.com/bionic/libqt5core5a)
  - focal -- [5.12.8](https://packages.ubuntu.com/focal/libqt5core5a)

  As another Ubuntu LTS is coming soon, it seems unreasonable to stick to Qt 5.9 which support [ended](https://www.qt.io/blog/2017/06/07/renewed-qt-support-services) on 2020-05-31. Anyway, it's still possible to build Bitcoin Core GUI with depends on bionic system.

  Bumping the minimum Qt version allows to make code safer and more reliable, e.g.:
  - functor-parameter overload of [`QMetaObject::invokeMethod`](https://doc.qt.io/qt-5/qmetaobject.html#invokeMethod-4)
  - fixed https://bugreports.qt.io/browse/QTBUG-10907

  An example of the patch using the functor-overload of `QMetaObject::invokeMethod`:
  ```diff
  --- a/src/qt/walletmodel.cpp
  +++ b/src/qt/walletmodel.cpp
  @@ -349,7 +349,7 @@ bool WalletModel::changePassphrase(const SecureString &oldPass, const SecureStri
   static void NotifyUnload(WalletModel* walletModel)
   {
       qDebug() << "NotifyUnload";
  -    bool invoked = QMetaObject::invokeMethod(walletModel, "unload");
  +    bool invoked = QMetaObject::invokeMethod(walletModel, &WalletModel::unload);
       assert(invoked);
   }

  ```
  It uses the same new syntax as signal-slot connection with compile-time check. Also see bitcoin/bitcoin#16348.

  This PR is intended to be merged early [after](https://github.com/bitcoin/bitcoin/issues/22969) branching `23.x` off.

ACKs for top commit:
  MarcoFalke:
    cr ACK 956f7322f60db7b8be551c9074b4c633e514079d
  fanquake:
    ACK 956f7322f60db7b8be551c9074b4c633e514079d

Tree-SHA512: 3d652bcdcd990ce785ad412ed70234d4f27743895e535a53ed44b35d4afc3052e066c4c84f417e30bc53d0a3dd9ebed62444c57b7c765cb1e9aa687fbf866877

5 files changed, 4 insertions, 8 deletions

diff --git a/.cirrus.yml b/.cirrus.yml
index 82aa39b296..fce3a1bb8e 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -195,7 +195,7 @@ task:
     FILE_ENV: "./ci/test/00_setup_env_i686_centos.sh"
 
 task:
-  name: '[previous releases, uses qt5 dev package and some depends packages, DEBUG] [unsigned char] [bionic]'
+  name: '[previous releases, uses qt5 dev package and some depends packages, DEBUG] [unsigned char] [buster]'
   previous_releases_cache:
     folder: "releases"
   << : *GLOBAL_TASK_TEMPLATE
diff --git a/ci/test/00_setup_env_native_qt5.sh b/ci/test/00_setup_env_native_qt5.sh
index f8b366e77f..53f933f514 100755
--- a/ci/test/00_setup_env_native_qt5.sh
+++ b/ci/test/00_setup_env_native_qt5.sh
@@ -7,7 +7,7 @@
 export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_native_qt5
-export DOCKER_NAME_TAG=ubuntu:18.04  # Check that bionic gcc-8 can compile our C++17 and run our functional tests in python3, see doc/dependencies.md
+export DOCKER_NAME_TAG=debian:buster  # Check that buster gcc-8 can compile our C++17 and run our functional tests in python3, see doc/dependencies.md
 export PACKAGES="gcc-8 g++-8 python3-zmq qtbase5-dev qttools5-dev-tools libdbus-1-dev libharfbuzz-dev"
 export DEP_OPTS="NO_QT=1 NO_UPNP=1 NO_NATPMP=1 DEBUG=1 ALLOW_HOST_PACKAGES=1 CC=gcc-8 CXX=g++-8"
 export TEST_RUNNER_EXTRA="--previous-releases --coverage --extended --exclude feature_dbcrash"  # Run extended tests so that coverage does not fail, but exclude the very slow dbcrash
diff --git a/configure.ac b/configure.ac
index 48684c7c98..06a208835b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1309,7 +1309,7 @@ else
   BITCOIN_QT_INIT
 
   dnl sets $bitcoin_enable_qt, $bitcoin_enable_qt_test, $bitcoin_enable_qt_dbus
-  BITCOIN_QT_CONFIGURE([5.9.5])
+  BITCOIN_QT_CONFIGURE([5.11.3])
 
   dnl Keep a copy of the original $QT_INCLUDES and use it when invoking qt's moc
   QT_INCLUDES_UNSUPPRESSED=$QT_INCLUDES
diff --git a/doc/dependencies.md b/doc/dependencies.md
index 99ff26f457..21af338119 100644
--- a/doc/dependencies.md
+++ b/doc/dependencies.md
@@ -20,7 +20,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
 | PCRE |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) |
 | Python (tests) |  | [3.6](https://www.python.org/downloads) |  |  |  |
 | qrencode | [3.4.4](https://fukuchi.org/works/qrencode) |  | No |  |  |
-| Qt | [5.15.2](https://download.qt.io/official_releases/qt/) | [5.9.5](https://github.com/bitcoin/bitcoin/issues/20104) | No |  |  |
+| Qt | [5.15.2](https://download.qt.io/official_releases/qt/) | [5.11.3](https://github.com/bitcoin/bitcoin/pull/24132) | No |  |  |
 | SQLite | [3.32.1](https://sqlite.org/download.html) | [3.7.17](https://github.com/bitcoin/bitcoin/pull/19077) |  |  |  |
 | XCB |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) (Linux only) |
 | systemtap ([tracing](tracing.md))| [4.5](https://sourceware.org/systemtap/ftp/releases/) |  |  |  | |
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index d6706fd009..3108c93d7c 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -883,11 +883,7 @@ void PolishProgressDialog(QProgressDialog* dialog)
 
 int TextWidth(const QFontMetrics& fm, const QString& text)
 {
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
     return fm.horizontalAdvance(text);
-#else
-    return fm.width(text);
-#endif
 }
 
 void LogQtInfo()