Program crashes at the beginning of main() in debug mode, but runs through in Release mode

MackS

Qt Version: 6.5.3
QtCreator version: Qt Creator 14.0.1
Compiler setup:

After some testing to try and figure out what was causing it, I found that I could cause it to crash with just these lines:

int main(int argc, char *argv[])
{
    string test = "test";
    QString test1 = QString::fromStdString(test);
...

Where the debugger stops on the "test1" initialization with this stack trace:

I am completely baffled as to why it could crash this early in the program, and am at a loss as to where to look or what to try next. Any guidance as to what to investigate would be very much appreciated

JonB

@MackS
Do not use any Qt classes/code until after you have instantiated whichever you want derived from QCoreApplication, which should be about the first statement in main().

UPDATE
Apparently not for QString, I learn to my surprise. So this is not the issue. Doubtless @Christian-Ehrlicher's reply below is the correct answer.

Christian Ehrlicher

Don't mix debug and release libraries as you do (msvcrt release lib, Qt debug libs I would guess). How did you create your project? Please show the CMakeLists.txt.

MackS

Thank you for the quick responses! I'll try separating the libraries.

As for CMakeLists.txt, I don't see one for my project, just for submodules within it. Are they auto-generated?

Christian Ehrlicher

How do you create your project / visual studio solution? Manually?

MackS

Using qmake <project>.pro:

qmake steps:
C:/Qt/6.5.3/msvc2019_64/bin/qmake.exe <project>.pro -spec win32-msvc "CONFIG+=debug" "CONFIG+=qml_debug" && C:/Qt/Tools/QtCreator/bin/jom/jom.exe qmake_all

Make steps:
jom.exe in C:<projectPath>\Desktop_Qt_6_5_3_MSVC2019_64bit-Debug

jsulm

@MackS So, you're using QMake, then post the pro file.

MackS

QT += quick
QT += quickcontrols2
QT += core
QT += network
CONFIG += c++17

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    sources.cpp
    ...

HEADERS += \
    headers.h
    ...

RESOURCES += qml.qrc \
  prodRes.qrc \
  imagine-assets/imagine-assets.qrc

#Share files
INCLUDEPATH += $$PWD/../share $$PWD/../lib/gtest/include
release{ LIBS += -L$$PWD/../lib/gtest/msvc/x64/release }
debug{ LIBS += -L$$PWD/../lib/gtest/msvc/x64/debug }
LIBS += -lQt6Core -lQt6Gui -lQt6Quick -lQt6QuickControls2
LIBS += -L"C:\\Qt\\6.5.3\\msvc2019_64\\lib"

*msvc*: QMAKE_CXXFLAGS += /std:c++17 /DWINDOWS=1 /DNOFILELOCKING=1
#*msvc*: QMAKE_LFLAGS += /DEBUG:FULL

*wasm*: QMAKE_CXXFLAGS += -std=c++17 -Wc++17-extensions -DNOFILELOCKING=1 -DZIP_STD -DUNIX -mnontrapping-fptoint
*wasm*: QMAKE_LFLAGS += -s \"BINARYEN_TRAP_MODE=\'clamp\'\"
#*wasm*: QMAKE_LFLAGS += -s \"BINARYEN_TRAP_MODE=\'clamp\'\" -s LEGACY_VM_SUPPORT=1 -s WASM=0


#QMAKE_CXXFLAGS += -showIncludes

#load(moc)
#QMAKE_MOC += -DQTMOCBUILD=1

SOURCES += \
  otherSources...

HEADERS += \
  otherHeaders...

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

#Enable TLS/SSL
EXTRA_QT_PLUGINS=tls
CONFIG += ssl

TARGET = trgt
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

FORMS +=

DESTDIR = ../run


#RC_FILE = prod.rc
RC_ICONS = prod.ico
VERSION = vers
QMAKE_TARGET_COMPANY = comp
QMAKE_TARGET_PRODUCT = prod
QMAKE_TARGET_DESCRIPTION = desc
QMAKE_TARGET_COPYRIGHT = cr

DISTFILES += \
    config.cfg

# copy all the files in the config dir to the destination dir...
copyconfig.commands = $(COPY_DIR) $$shell_path($$PWD/config) $$shell_path($$DESTDIR)
first.depends = $(first) copyconfig
export(first.depends)
export(copyconfig.commands)
QMAKE_EXTRA_TARGETS += first copyconfig

I took the liberty to wrap the file content in code tags, in future please use the provided button to place code fragments in the appropriated code block or manually wrap it using ```
@J.Hilk

jsulm

@MackS said in Program crashes at the beginning of main() in debug mode, but runs through in Release mode:

LIBS += -lQt6Core -lQt6Gui -lQt6Quick -lQt6QuickControls2

Why? This is not needed (QT += does what is needed to link Qt modules). This way you tell QMake to link release versions of these libs even in debug builds.

MackS

Removing that LIBS += line did it! Thank you all very much for your time and help!

RobertB

@JonB qbytearray can be constructed before QCoreApplication too.

JonB

@RobertB
Yes, now that I know that non-QObject shared objects like QString do not require an application object that will apply to QByteArray and other similar types like QList etc.