error: allocation of incomplete type ....

[J.Hilk]

Renaming a Qt Widget class with its own ui file is never a trivial task. There's a lot of magic code generating happening on Qt/uic side that is easily broken because not everything is always regenerated on each compile. An imperfect system for sure.

That said, did you add the renamed ui file to the FORMS inside you pro file, assuming you're using qmake and not cmake?

FORMS += \
    MainWindow_TERMINAL_ORIGINAL.ui //presumably. Case shouldn't matter on windows, but does on linux 

without it, the compiler won't generate obj files for your gui-header ui_mainwindow_TERMINAL_ORIGINAL.h and you will get an incomplete type type error

[Anonymous_Banned275]

@J-Hilk
Thanks for all replies.

Here is my modified .pro

QT += widgets serialport
requires(qtConfig(combobox))

TARGET = terminal
TEMPLATE = lib


SOURCES += \
    main.cpp \
    mainwindow_TERMINAL_ORIGINAL.cpp \
    settingsdialog.cpp \
    console.cpp

HEADERS += \
    mainwindow_TERMINAL_ORIGINAL.h \
    settingsdialog.h \
    console.h

FORMS += \
    mainwindow_TERMINAL_ORIGINAL.ui \
    settingsdialog.ui

RESOURCES += \
    terminal.qrc

target.path = $$[QT_INSTALL_EXAMPLES]/serialport/terminal
INSTALLS += target

message(" add Mar19 original simple terminal code ")
message(" changed to lib  ")

[Anonymous_Banned275]

@JonB The line count is BEFORE I deleted "credit lines" - irrelevant to find the solution.

[JonB]

@AnneRanch Thanks. So did you look at my third point?

[Anonymous_Banned275]

@JonB Here is .cpp - minus the "credit lines"

One of the errors gives " note forward declaration" which just enforces " incomplete type" errors...

It is still unclear where is this "missing type"....

//#include "mainwindow.h"
// renamed
#include "mainwindow_TERMINAL_ORIGINAL.h"
#include "ui_mainwindow_TERMINAL_ORIGINAL.h"

//#include "ui_mainwindow.h"
#include "console.h"
#include "settingsdialog.h"

#include <QLabel>
#include <QMessageBox>

//! [0]
MainWindow_TERMINAL_ORIGINAL::MainWindow_TERMINAL_ORIGINAL(QWidget *parent) :
    QMainWindow(parent),
    m_ui(new Ui::MainWindow_TERMINAL_ORIGINAL),
    m_status(new QLabel),
    m_console(new Console),
    m_settings(new SettingsDialog),
//! [1]
    m_serial(new QSerialPort(this))
//! [1]
{
//! [0]
    m_ui->setupUi(this);
    m_console->setEnabled(false);
    setCentralWidget(m_console);

    m_ui->actionConnect->setEnabled(true);
    m_ui->actionDisconnect->setEnabled(false);
    m_ui->actionQuit->setEnabled(true);
    m_ui->actionConfigure->setEnabled(true);

    m_ui->statusBar->addWidget(m_status);

    initActionsConnections();

    connect(m_serial, &QSerialPort::errorOccurred, this, &MainWindow_TERMINAL_ORIGINAL::handleError);

//! [2]
    connect(m_serial, &QSerialPort::readyRead, this, &MainWindow_TERMINAL_ORIGINAL::readData);
//! [2]
    connect(m_console, &Console::getData, this, &MainWindow_TERMINAL_ORIGINAL::writeData);
//! [3]
}
//! [3]

MainWindow_TERMINAL_ORIGINAL::~MainWindow_TERMINAL_ORIGINAL()
{
    delete m_settings;
    delete m_ui;
}

//! [4]
void MainWindow_TERMINAL_ORIGINAL::openSerialPort()
{
    const SettingsDialog::Settings p = m_settings->settings();
    m_serial->setPortName(p.name);
    m_serial->setBaudRate(p.baudRate);
    m_serial->setDataBits(p.dataBits);
    m_serial->setParity(p.parity);
    m_serial->setStopBits(p.stopBits);
    m_serial->setFlowControl(p.flowControl);
    if (m_serial->open(QIODevice::ReadWrite)) {
        m_console->setEnabled(true);
        m_console->setLocalEchoEnabled(p.localEchoEnabled);
        m_ui->actionConnect->setEnabled(false);
        m_ui->actionDisconnect->setEnabled(true);
        m_ui->actionConfigure->setEnabled(false);
        showStatusMessage(tr("Connected to %1 : %2, %3, %4, %5, %6")
                          .arg(p.name).arg(p.stringBaudRate).arg(p.stringDataBits)
                          .arg(p.stringParity).arg(p.stringStopBits).arg(p.stringFlowControl));
    } else {
        QMessageBox::critical(this, tr("Error"), m_serial->errorString());

        showStatusMessage(tr("Open error"));
    }
}
//! [4]

//! [5]
void MainWindow_TERMINAL_ORIGINAL::closeSerialPort()
{
    if (m_serial->isOpen())
        m_serial->close();
    m_console->setEnabled(false);
    m_ui->actionConnect->setEnabled(true);
    m_ui->actionDisconnect->setEnabled(false);
    m_ui->actionConfigure->setEnabled(true);
    showStatusMessage(tr("Disconnected"));
}
//! [5]

void MainWindow_TERMINAL_ORIGINAL::about()
{
    QMessageBox::about(this, tr("About Simple Terminal"),
                       tr("The <b>Simple Terminal</b> example demonstrates how to "
                          "use the Qt Serial Port module in modern GUI applications "
                          "using Qt, with a menu bar, toolbars, and a status bar."));
}

//! [6]
void MainWindow_TERMINAL_ORIGINAL::writeData(const QByteArray &data)
{
    m_serial->write(data);
}
//! [6]

//! [7]
void MainWindow_TERMINAL_ORIGINAL::readData()
{
    const QByteArray data = m_serial->readAll();
    m_console->putData(data);
}
//! [7]

//! [8]
void MainWindow_TERMINAL_ORIGINAL::handleError(QSerialPort::SerialPortError error)
{
    if (error == QSerialPort::ResourceError) {
        QMessageBox::critical(this, tr("Critical Error"), m_serial->errorString());
        closeSerialPort();
    }
}
//! [8]

void MainWindow_TERMINAL_ORIGINAL::initActionsConnections()
{
    connect(m_ui->actionConnect, &QAction::triggered, this, &MainWindow_TERMINAL_ORIGINAL::openSerialPort);
    connect(m_ui->actionDisconnect, &QAction::triggered, this, &MainWindow_TERMINAL_ORIGINAL::closeSerialPort);
    connect(m_ui->actionQuit, &QAction::triggered, this, &MainWindow_TERMINAL_ORIGINAL::close);
    connect(m_ui->actionConfigure, &QAction::triggered, m_settings, &SettingsDialog::show);
    connect(m_ui->actionClear, &QAction::triggered, m_console, &Console::clear);
    connect(m_ui->actionAbout, &QAction::triggered, this, &MainWindow_TERMINAL_ORIGINAL::about);
    connect(m_ui->actionAboutQt, &QAction::triggered, qApp, &QApplication::aboutQt);
}

void MainWindow_TERMINAL_ORIGINAL::showStatusMessage(const QString &message)
{
    m_status->setText(message);
}

[JonB]

@AnneRanch
I still suggest it's likely to be the 3rd (or 2nd) point. When you renamed, did you go not just rename the .ui file but also go into editing it and change the class name inside it?

[Anonymous_Banned275]

@JonB OK. it is back to "how is "ui_...h " created / build and where .

My next logical step will be to let Qt build "QDialog " project and add it to my sub project. From scratch and see how it actually builds "ui_.h" header AND WHERE .

That may resolve my missing step...

[JonB]

@AnneRanch
This is a guess, but your behaviour would be explained if: you look at the top few lines (about line #20) of the ui_mainwindow_TERMINAL_ORIGINAL.h file, wherever you are including it from. If that still shows class Ui_mainwindow_TERMINAL instead of the intended class Ui_mainwindow_TERMINAL_ORIGINAL that should cause the error message you showed.

BTW: The build process always places the generated ui_....h file in the build output directory, like ../build-yourprojectname-Desktop-Debug. If you copy it into your source directory, or somehow a file of that name ends up there, it will go wrong as you update the .ui file.

[Anonymous_Banned275]

@JonB SOLVED
BINGO!!! OF forgot to change the object in .ui GUI .
Been there , done that before... feel pretty stupid.
It really helped to have all participants to chime in,
appreciate that very much,

[Anonymous_Banned275]

@AnneRanch UPDATE / GOTCHA
When reusing (C++ "feature") project in subproject one better change / rename "MainWindow" class name. .

I start with renaming the existing class header file. QtCreator gives an option to rename both .cpp and .ui
BUT you must start with renaming the header file FIRST.

Then you can rename the MainWindow class and that will change the "object" name in .ui file! l

Another "GOTCHA" - the #include ui_ file , generated from .ui file MUST be changed manually !

Good luck...