Qt Creator displaying warnings related to C++98

GregB

I'm running Qt Creator 15.0.1 on Windows, and I'm getting warnings about incompatibilites with C++98. This is appearing as annotations in code editor.

I've added the following to the .pro file, but it didn't change any behavior

CONFIG -= c++98
CONFIG += c++11
CONFIG += c++17

How can I get the clang code model to ignore C++98 issues?

aha_1980

@GregB You are currently adding both C++11 and C++17 - please choose one of them. If you use an older Qt and therefore qmake version, you might need to replace C++17 with C++1z

Also, I doubt that CONFIG -= c++98 has any meaning, see https://doc.qt.io/qt-6/qmake-variable-reference.html#config for known variables.

If you still encounter problems, please share the code you are getting warnings with.

Regards

GregB

I changed the .pro file to only contain the c++17. The warnings that I'm getting are within Qt Creator, not from the build process. Some example warnings are below:

M:\nidb\src\nidb\modulePipeline.cpp:300: warning: 'auto' type specifier is incompatible with C++98
M:\nidb\src\nidb\modulePipeline.cpp:300: warning: If initialization statements are incompatible with C++ standards before C++17
M:\nidb\src\nidb\modulePipeline.cpp:1377: warning: Initialization of initializer_list object is incompatible with C++98
M:\nidb\src\nidb\modulePipeline.cpp:1867: warning: 'auto' type specifier is incompatible with C++98
M:\nidb\src\nidb\modulePipeline.cpp:1867: warning: If initialization statements are incompatible with C++ standards before C++17
M:\nidb\src\nidb\modulePipeline.cpp:2188: warning: Universal character name referring to a control character is incompatible with C++98

aha_1980

@GregB could you also share the relevant code lines?

GregB

Line 300

foreach (int sid, studyids) {

Line 1377

QStringList bidsflags = { "BIDS_SUBJECTDIR_UID", "BIDS_STUDYDIR_STUDYNUM" };

Line 1867

foreach (QString group, groups) {

I'm not sure that the code is invalid? This code builds without warnings or error. The only issue is the warnings within Qt Creator generated by clangd within the editor. I recently upgraded my computer and reinstalled Qt Creator, and that's when I started getting the warnings. I was using 15.0.1 before, and 15.0.1 now. I must have had a setting turned off on my previous computer related to clangd, but I don't know what the setting is.

JonB

@GregB
Up to you, but you could change foreach() to for ( : ), and I would guess remove the = in the middle one? Not that you have to, but these are newer constructs and I guess it's moaning about the older ones?

aha_1980

@GregB Thanks. Looking at the foreach source code there is indeed a line for (auto name = QtPrivate::qMakeForeachContainer(container); name.i != name.e; ++name.i) which is valid C++11 and higher code.

So I think for some reason the code model does not pick up the C++17 specifier. Can you try a minimal "Hello World" style example?

@JonB Be careful with such suggestions. Changing foreach() to range-based for requires a studies with diploma exam ;)

Regards

JonB

@aha_1980 said in Qt Creator displaying warnings related to C++98:

@JonB Be careful with such suggestions. Changing foreach() to range-based for requires a studies with diploma exam ;)

If you say so! I only know that I use for instead of foreach (at least in similar cases to what the OP shows above, an int and a QString and their lists) and never had any issues?

aha_1980

@JonB: You think you don't have any issues before you read the post Goodbye Q_FOREACH! I mentioned.

Regards

JonB

@aha_1980
But just to round off, I thought there are no issues for the specific int-in-list and QString-in-QStringList OP's cases as shown, or are there?

aha_1980

@JonB: not for the int and the QString , but probably for the corresponding lists. But for the details, you will have to read the mentioned post.

GregB

Thanks for the comments. So I don't think there's anything wrong with the code itself. It seems to be a configuration with Qt Creator and clangd that is ignoring the c++17 specification in the .pro file.

I found a previous post about this issue, and how they fixed it: https://forum.qt.io/topic/109856/incompatible-with-c-98-warnings-since-qt-creater-update/3

But that post is 5 years old, and none of the options they used to fix the issue exist in in the current Qt Creator.