How to switch off specific warnings in Qt Creator

DiBosco

Folks,

I am getting lots of depricated warnings (I cannot upgrade to a newer version of Qt BTW, so, for me, this is not going to be a solution I have seen suggested elsewhere). After doing loads of trawling around, the method seems to be to add to your .pro file:

QMAKE_CXXFLAGS_WARN_OFF -= -Wdeprecated-copy

However, this makes no an iota of difference.

This is an example of a full warning message:

/path/qtransform.h:376: warning: implicitly-declared ‘QTransform::QTransform(const QTransform&)’ is deprecated [-Wdeprecated-copy]
In file included from /path//QtGui/qbrush.h:43,
                 from /path//qpalette.h:39,
                 from /path//qwidget.h:41,
                 from /path//QWidget:1,
                 from ../PI03SW05/crc.h:5,
                 from ../PI03SW05/crc.cpp:1:
/path/qtransform.h: In function ‘QTransform operator*(const QTransform&, qreal)’:
/path/qtransform.h:376:17: warning: implicitly-declared ‘QTransform::QTransform(const QTransform&)’ is deprecated [-Wdeprecated-copy]
  376 | { QTransform t(a); t *= n; return t; }
      |                 ^
/path/qtransform.h:121:17: note: because ‘QTransform’ has user-provided ‘QTransform& QTransform::operator=(const QTransform&)’
  121 |     QTransform &operator=(const QTransform &);

Anyone know what I am doing wrong here and (with explicit instructions) how to fix this please? Am using 5.6.3 on Linux FWIW.

Thanks :)

DiBosco

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DiBosco

This post is deleted!

JonB

@DiBosco said in How to switch off specific warnings in Qt Creator:

However, this makes no an iota of difference.

According to https://forum.qt.io/post/649283 you should:

Use CONFIG += warn_off in your .pro file to disable warnings. This will make sure the compiler is called with all the flags set in QMAKE_CXXFLAGS_WARN_OFF (which should be automatically set by the default mkspecs, so usually no reason to change it).

DiBosco

Using CONFIG += warn_off switches of ALL warnings though and I don't want that.

JonB

@DiBosco
Did you actually try it though? I read the answer as indicating/suggesting that CONFIG += warn_off is required to make QMAKE_CXXFLAGS_WARN_OFF be taken into account? The OP there seemed to say same as you: setting QMAKE_CXXFLAGS_WARN_OFF alone did not have any effect.

Try it to see if you can tell it makes a difference? Check the actual options being passed to the gcc in each case? Figure how to make QMAKE_CXXFLAGS_WARN_OFF actually affect things if it does it right from the CONFIG statement but not in your case?

DiBosco

@JonB Yes, that's how I know it suppresses all warnings :)

If I put this in my .pro file:

CONFIG += warn_off
QMAKE_CXXFLAGS_WARN_OFF -= -Wdeprecated-copy

No warnings at all. If I take out the:

CONFIG += warn_off

line then all warnings are present.

JonB

@DiBosco
I already suggested: you ought find out why (apparently, according to you and the other poster) that without CONFIG += warn_off setting QMAKE_CXXFLAGS_WARN_OFF -= -Wdeprecated-copy has no effect. Then maybe you will be able to remove CONFIG and know what you have to do to make QMAKE_CXXFLAGS_WARN_OFF -= -Wdeprecated-copy work on its own.

Not that I know anything about this, but I would guess that QMAKE_CXXFLAGS_WARN_OFF is only used at all if you have CONFIG += warn_off, i.e. the latter "activates" the former's flags to be used. Without that configuration QMAKE_CXXFLAGS_WARN_OFF is not passed to compiler. If you want -Wdeprecated-copy in other circumstances than with all other warnings turned off I would presume you should use another variable which is always passed to compiler. Something like QMAKE_CXXFLAGS? Does that satisfy you?

DiBosco

@JonB

I'm not sure I've made it clear that with

CONFIG += warn_off

All warnings go. So, for example, unused variables no long show up (which I want to see).

I want all deprecated warnings to go, but I want to see other types of warning.

DiBosco

@DiBosco said in How to switch off specific warnings in Qt Creator:

@JonB

I'm not sure I've made it clear that with
CONFIG += warn_off
All warnings go. So, for example, unused variables no long show up (which I want to see).

I want all deprecated warnings to go, but I want to see other types of warning.

PS Trying to find out what I ought to do is what I'm doing here. I spent absolutely ages trawling round various sites such as here and Stack Overflow to no avail.

JonB

@DiBosco said in How to switch off specific warnings in Qt Creator:

All warnings go. So, for example, unused variables no long show up (which I want to see).

I want all deprecated warnings to go, but I want to see other types of warning.

I know this. And I suggested why QMAKE_CXXFLAGS_WARN_OFF probably has no effect and precisely what you should do, which you apparently have not tried.....

DiBosco

@JonB

I think I'm missing something here because I said a few posts up I tried:

CONFIG += warn_off
QMAKE_CXXFLAGS_WARN_OFF -= -Wdeprecated-copy

So I have tried QMAKE_CXXFLAGS_WARN_OFF. Sorry if I'm being slow here, but if that's not what you mean I need something more explicit to try.

aha_1980

@DiBosco Have you already seen https://stackoverflow.com/questions/22129383/removing-unused-parameters-warning-in-qtcreator ?

For your case, it would be: QMAKE_CXXFLAGS_WARN_ON += -Wno-deprecated-copy

Regards

JonB

@DiBosco
:)

Forget about CONFIG ..., remove it.
Forget about QMAKE_CXXFLAGS_WARN_OFF ..., remove it.
Try this:

If you want -Wdeprecated-copy in other circumstances than with all other warnings turned off I would presume you should use another variable which is always passed to compiler. Something like QMAKE_CXXFLAGS? Does that satisfy you?

I cannot be sure which one to use, but what happens if you add a line reading:

QMAKE_CXXFLAGS -= -Wdeprecated-copy

If that does not work we (you!) need to understand what is adding -Wdeprecated-copy on the gcc compiler line (I asked you to look at the actual line being generated, does it have that option?) and then presumably something like THE_MACRO_WHICH_ADDED_IT -= -Wdeprecated-copy to remove it?

P.S.
Since @aha_1980 has just chimed in to say there is a QMAKE_CXXFLAGS_WARN_ON and a -Wno-deprecated-copy which can be added you should try that. If by any chance that does not work you might have to put it on QMAKE_CXXFLAGS, but try what he says first.

DiBosco

@aha_1980 said in How to switch off specific warnings in Qt Creator:

@DiBosco Have you already seen https://stackoverflow.com/questions/22129383/removing-unused-parameters-warning-in-qtcreator ?

For your case, it would be: QMAKE_CXXFLAGS_WARN_ON += -Wno-deprecated-copy

Regards

Ah, yes I had seen that. The English in the most upticked reply just made me go "What?". Just could not understand what they were saying, but I had tried:

QMAKE_CXXFLAGS_WARN_ON += -Wdeprecated-copy

Thinking why on earth would putting the warning on make it disappear, but out of desperation I gave it a go. Had I realised it needed -Wno-deprecated-copy, not -Wdeprecated-copy I'd've been fine hours ago.

Many thanks for that, now doing just what I want.

Also @JonB Thanks for your help too.