Debug_and_release: how to get rid of autogenerated debug/release folders

JamesBrown147

oh, I just found the solution!

If you set the MOC_DIR variable, then qmake does not generate the folders. My code looks like this now:

DESTDIR = bin/debug
OBJECTS_DIR = bin/debug
MOC_DIR = bin/debug

miroslav

@JamesBrown147: Watch out, these directories will now be used for debug and release builds, unless you added logic around it.

xenotrax

I got the same problem. :-( (error only on Windows no problems with Fedora )

QDir::currentPath() is
C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Debug

but the real exe is in
C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Debug\debug

automatic created folders are
C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Debug\debug
C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Debug\release

C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Release\debug
C:\Qt\ding\build-poppi-Desktop_Qt_5_3_MSVC2013_64bit-Release\release

DanWatkins

This post is deleted!

Mozi

@sayezz @xenotrax
Hi! If you are using Windows, please see this: c++ - Qt Creator creates both a debug and a release folder inside the designated debug folder - Stack Overflow

CONFIG -= debug_and_release debug_and_release_target

Putting this line into the .pro file solves my problem.

You can add a test about the platform to confirm that only Qt (qmake) on Windows will change this configuration, like this:

win32 {
    message($$CONFIG)
    CONFIG -= debug_and_release debug_and_release_target
    message($$CONFIG)
}

edit on 2/8/2020:

Add CONFIG -= debug_and_release is enough.

aha_1980 · edit on 2/8/2020:

Hi @Mozi,

debug_and_release is only set on Windows, so no need for a scope.

And you need to make sure to use shadow-building if you disable that! The reason this variable is set by default is that on Windows it's impossible to mix debug and release objects.

If that is ok for you, you can savely disable that variable (like I do), as it makes the whole handling more easy.

Regards

Mozi

Hi @aha_1980 ,
Thanks for your reply.
I noticed that the Shadow build feature is enabled by default, so I can remove debug_and_release safely.
https://doc.qt.io/qtcreator/creator-build-settings.html#qmake-build-configuration

Mozi

This post is deleted!

Mozi

And, @aha_1980 ,

on Windows it's impossible to mix debug and release objects.

I cannot get the point, could you please explain a little more?
Thanks.

aha_1980

@Mozi The MSVC compiler uses different runtime libs for debug and release builds. Mixing them, e.g. using a debug DLL with a release program may crash.

Things are different for the MinGW compiler though, which is the reason Qt 5.14 is compiled without debug_and_release on this platform.

Regards

Mozi

Hi @aha_1980 .
There are some new problems but it may be off-topic. Thanks for your previous reply.

When debug_and_release was removed, the flag build_pass was removed too. And I discovered that build_pass will affect the windeployqt target's behavior. Here is a code snippet of windeployqt.prf from Qt 5.14.1.

# Extra target for running windeployqt
qtPrepareTool(QMAKE_WINDEPLOYQT, windeployqt)
build_pass {
    #...
    windeployqt.target = windeployqt
    windeployqt.commands = $$QMAKE_WINDEPLOYQT $$WINDEPLOYQT_OPTIONS -list target $$WINDEPLOYQT_TARGET > $$WINDEPLOYQT_OUTPUT
    
    windeployqt_clean.commands = if exist $$WINDEPLOYQT_OUTPUT for /f %i in ($$WINDEPLOYQT_OUTPUT) do $$QMAKE_DEL_FILE %~fi && $$QMAKE_DEL_DIR %~pi
    #...
} else {
    windeployqt.CONFIG += recursive
    windeployqt_clean.CONFIG += recursive
}
QMAKE_EXTRA_TARGETS += windeployqt windeployqt_clean

The problem, makes me confused, is the relationship between the CONFIGs mentioned above. If there is no debug_and_release flag, windeployqt will do nothing. I know I can add build_pass to CONFIG manually, but... What's the original purpose of this design?

Moreover, I found that if I use default CONFIG (contains debug_and_release and debug_and_release_target) with windeployqt, make windeployqt will complain about no release target exists (under debug mode) or no debug target exists (under release mode), and the process will stop. Is this by design? And what's the reason?

Thanks!
Regards

aha_1980

Hi @Mozi,

for which compiler is that? MSVC or MinGW?

Anyway, I can't answer these questions, I'm not that deep in qmake. You might want to ask these questions on the Qt Interest mailing list, where more developers might be able to help you.

Regards

Mozi

Hi @aha_1980 .
I'm using MSVC2017. And thanks for your suggestion :-)

Regards

Mozi

The new discovery record:
If I add build_pass, Qt Creator will complain about the Makefile after qmake:

Could not parse Makefile. The build in \path\to\the\build will be overwritten.

Well, I don't know if it's harmful to manually add this argument by the developer.
It's not well-documented...

The only build_pass phrase in the page (https://doc.qt.io/qt-5/qmake-variable-reference.html):

During the latter passes, **build_pass** and the respective debug or release option is appended to CONFIG. This makes it possible to perform build-specific tasks. For example:

build_pass:CONFIG(debug, debug|release) {
    unix: TARGET = $$join(TARGET,,,_debug)
    else: TARGET = $$join(TARGET,,,d)
}

Mozi · edit on 2/8/2020:

Ummm, I think we should NOT remove the debug_and_release and debug_and_release_target flags, whether we need multiple build configurations or not.

debug_and_release & Shadow build

In VS (VC++), the output folders (Debug and Release) are in the same directory as the source file (The root of the source folder).
In Qt, if the debug_and_release flag exists, the structure of the output folder is very similar to VS.

/
+---project.pro
+---main.cpp
+---debug
|       *.obj
|       moc_*.cpp
|       target.exe
|
+---release
        *.obj
        moc_*.cpp
        target.exe

Shadow build wants to make the source tree clean and place all generated files in the build directory. For macOS and Linux, it works well. However, for Windows, these files will be placed in nested folders (extra Debug and Release folders) because of the debug_and_release flag. I know the structure looks weird, but I think we should keep it as it is and avoid potential impacts (for example, #19 of this thread).

Ref:

https://stackoverflow.com/questions/35999940/qt-after-specifying-output-directory-it-still-create-debug-and-release-folders-i#answer-36000284

Term	Meaning
Shadow build	Shadow building means building a project in a separate directory, the build directory. The build directory is different from the source directory. One of the benefits of shadow building is that it keeps your source directory clean, which makes it faster to switch between build configurations. Therefore, shadow building is the best practice if you need many build configurations for a single set of source files.

from: https://doc.qt.io/qtcreator/creator-glossary.html#glossary-shadow-build

debug_and_release_target

The difference between the Makefile.Release file with (red) and without (green) the debug_and_release_target flag:

...
- DESTDIR        = release\ #avoid trailing-slash linebreak
+ DESTDIR        =  #avoid trailing-slash linebreak
- DESTDIR_TARGET = release\project.exe
+ DESTDIR_TARGET = project.exe
...
first: all
- all: Makefile.Release  release\project.exe
+ all: Makefile.Release  project.exe
...
- release\project.exe: ...
+ project.exe: ...
...

Without debug_and_release_target, if debug_and_release is enabled, the final binary file will be generated in the folder same as Makefile.

Option	Description
debug_and_release_target	This option is set by default. If `debug_and_release` is also set, the debug and release builds end up in separate debug and release directories.

from: https://doc.qt.io/qt-5/qmake-variable-reference.html

Correct me if I'm wrong. Thanks for your reading.

Mozi

Ummm, I missed this UN-document.

...

There are also several values that qmake will dynamically set in CONFIG when it is writing a makefile (not when XCode project files are being written) other than the primary Makefile - i.e. the additional subsidiary makefiles when debug_and_release and/or static_and_shared have been set:

* build_pass — a subsidiary makefile is being written (build_pass is not set when the primary Makefile is being written).
* Debug and DebugBuild — when debug_and_release has been set and the makefile filename extension contains "Debug".
* Release and ReleaseBuild — when debug_and_release has been set and the makefile filename extension contains "Release".
* Static and StaticBuild — when static_and_shared has been set and the makefile filename extension contains "Static".
* Shared and SharedBuild — when static_and_shared has been set and the makefile filename extension contains "Shared".

...

from: https://wiki.qt.io/Undocumented_QMake#Config_features