What version of QtQuick.Controls is installed on my ubuntu system?

[Tom asso]

I'm running ubuntu 20.04. 3, and have installed qt 5.12.8 components with 'apt'.
I install QtQuick.Controls with:

sudo apt-get install qml-module-qtquick-controls

I need to know which version of QtQuick.Controls is installed, because if my qml file contains this:

import QtQuick.Controls

I get a runtime error:

qrc:/main.qml:-1 Library import requires a version

Now how do I know which version of QtQuick.Controls is installed?

apt list --installed | grep qtquick-controls
qml-module-qtquick-controls/focal,now 5.12.8-0ubuntu2 amd64 [installed]

This seems to say QtQuick.Controls 5.12.8 is installed. But if my qml contains this:

import QtQuick.Controls 5.12.8

I get this runtime error:

QQmlApplicationEngine failed to load component
qrc:/main.qml:4 Expected token `;'

So it seems the '.8' suffix is not allowed. I put this in my qml file:

import QtQuick.Controls 5.12

I get this runtime error:

QQmlApplicationEngine failed to load component
qrc:/main.qml:4 module "QtQuick.Controls" version 5.12 is not installed

EDIT: This page indicates that QtQuick.Controls version 2.12 comes with Qt 5.12. However "import QtQuick.Controls 2.12" also results in this error at runtime:

qrc:/main.qml:4 module "QtQuick.Controls" version 2.12 is not installed

Can someone please help me sort this out? Thanks!

[Tom asso]

I also asked this question on stackoverflow.com, and got this response:
"You should install qml-module-qtquick-controls2 not qml-module-qtquick-controls" - now the runtime finds "import QtQuick.Controls 2.12" as expected

[ChrisW67]

2.12 should be correct.
Do you have the Qt Declarative module installed?

[Tom asso]

@ChrisW67 - Yes, apt packages qtdeclarative5-dev and qtdeclarative5-dev-tools are both installed.

[Tom asso]

I also asked this question on stackoverflow.com, and got this response:
"You should install qml-module-qtquick-controls2 not qml-module-qtquick-controls" - now the runtime finds "import QtQuick.Controls 2.12" as expected