C++ - Application crashes at QsciScintilla auto complete

JackMyson

I have installed the QScintilla 2 into my MacBook, and I am currently using C++ and the Qt framework to develop a QScintilla-related text editor. Briefly introduced that I have a main window class, an editor class, and some lexers.

My problem is, I discovered that when I type into the application (that means typing into the editor, triggered QKeyEvent*), the application will crash without a reason.

I am using Qt Creator as the IDE now, so I may show you the application output message:

19:56:13: Starting /Users/jason/Desktop/Projects/Text/bin/Text.app/Contents/MacOS/Text...
19:56:23: /Users/jason/Desktop/Projects/Text/bin/Text

When trying the LLDB for the application using Qt Creator's built-in debugger, the crash message shows below:

20:01:47: Debugging /Users/jason/Desktop/Projects/Text/bin/Text.app/Contents/MacOS/Text ...

got fallback qt version 0x60402
2023-03-10 20:02:02.734376+0800 Text[5183:2288553] SecTaskLoadEntitlements failed error=22 cs_flags=20, pid=5183
2023-03-10 20:02:02.734572+0800 Text[5183:2288553] SecTaskCopyDebugDescription: Text[5183]/0#-1 LF=0
2023-03-10 20:02:05.190416+0800 Text[5183:2288553] SecTaskLoadEntitlements failed error=22 cs_flags=20, pid=5183
2023-03-10 20:02:05.190551+0800 Text[5183:2288553] SecTaskCopyDebugDescription: Text[5183]/0#-1 LF=0
20:03:08: Debugging of /Users/jason/Desktop/Projects/Text/bin/Text.app/Contents/MacOS/Text has finished.

lldb for the application

I'm currently using:

macOS version 11.7.3 Big Sur on Intel MacBook Air mid-2013
Qt 6.4.2 for macOS
C++ 17
XCode 13

Here's shown the MRE:

editor.cpp

#include "editor.h"
#include "lexerpython3.h"

Editor::Editor(QWidget* parent) : QsciScintilla(parent)
{
    LexerPython3 *m_lexerPython3 = new LexerPython3(m_font);
    setCallTipsPosition(CallTipsPosition::CallTipsBelowText);
    setCallTipsVisible(-1);
    setAutoIndent(true);
    setAutoCompletionSource(QsciScintilla::AutoCompletionSource::AcsAll);
    setAutoCompletionThreshold(1);
    setAutoCompletionCaseSensitivity(false);
    setAutoCompletionReplaceWord(true);
}

lexerpython3.h

#ifndef LEXERPYTHON3_H
#define LEXERPYTHON3_H

#include <QObject>
#include <QFont>

#include <Qsci/qscilexerpython.h>

class LexerPython3 : public QsciLexerPython
{
    Q_OBJECT

public:

    LexerPython3(QFont font, QObject* object = nullptr);

    const char *keywords(int set) const;

private:

    QFont m_font;

    const char* key = "and as assert break class continue def del elif else except exec "
                      "finally for from global if import in is lambda None not or pass "
                      "print raise return try while with yield";

    QString m_calltips;
};

#endif // LEXERPYTHON3_H

lexerpython3.cpp

#include "lexerpython3.h"

#include <QColor>
#include <Qsci/qsciapis.h>

LexerPython3::LexerPython3(QFont font, QObject* parent)
    : QsciLexerPython(parent)
{
    // Defining variables...
    m_font = font;

    m_calltips = "ArithmeticError() "
                 "AssertionError() "
                 ...
                 ...
            "__build_class__(func, name, a, *bases, [metaclass], **kwds) "
            "__import__(name, globals=None, locals=None, fromlist=(), level=0) "
            "all(iterable, /) "
            "anext(aiterator[, default]) "
            "any(iterable, /)";

    setFoldCompact(false);
    setFoldQuotes(true);
    setFoldComments(true);

    setIndentationWarning(QsciLexerPython::IndentationWarning::Inconsistent);
    setV2UnicodeAllowed(false);

    QsciAPIs api(this);

    for (const QString &item1 : QString(key).split(" "))
    {
        api.add(item1);
    }

    for (QString item2 : m_calltips.split(" "))
    {
        api.add(item2);
    }

    api.prepare();
}

const char* LexerPython3::keywords(int set) const
{
    if (set != 1)

        return 0;

    return key;
}

Any help or comments will be appreciated! Thanks!!

JackMyson

Oh... I figure it out. I think it's the problem of not using the pointer references.

// QsciAPIs api(this); // crashes!
QsciAPIs* api;
api = new QsciAPIs(this);
// Now it won't crash

for (const QString &s : /**/)
{
    ///...
///...
///...

SGaist

Hi,

I haven't used QScintilla for a very long time but aren't you using QsciAPIs the wrong way ?

JackMyson

@SGaist

Um... I don't really know. However, I've been using Python language in this way and I have translated it into C++ manually and directly. In Python, all the functions and classes works well and no exceptions are raised...

JackMyson

Oh... I figure it out. I think it's the problem of not using the pointer references.

// QsciAPIs api(this); // crashes!
QsciAPIs* api;
api = new QsciAPIs(this);
// Now it won't crash

for (const QString &s : /**/)
{
    ///...
///...
///...