moc: standard input:0: Note: No relevant classes found. No output generated.

Vlad48

I have project on qt 5.15.2(Community).
This project was build without issues, but after moving one to different directory no moc_* files are creating.
I tested on three different PC, on twos project was build, but on the third I can't.
How this issue can be fixed?
#moc

sierdzio

When moving the project, make sure to clean up any build artifacts:

.pro.user files
.qmake.stash
Makefile
etc.

Vlad48

Sure I made these many times without success.

sierdzio

Are you sure it is the same code? Same Qt version? Does the class moc is complaining about have Q_OBJECT macro in it?

Vlad48

No complaining about Q_OBJECT. The version is the same, all project files were copied to new folder. Moreover, in the old place on the same PC project was compiled fine using the same QT.
I work on Windows10x64, MinGW 8.1-x64.

sierdzio

Then I don't know what's wrong. Probably some error by moving the code, or misconfigured Qt, it's hard to say :/

KH-219Design

My first instinct was to scrutinize the main of moc itself, but I'm not seeing too many clues:

https://github.com/qt/qtbase/blob/d32f7dde257f6d/src/tools/moc/main.cpp#L573

My other thought is the infamous "MAX_PATH" limit of 260 char on windows: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file

Over the years, I have ended up pinning a handful of bizarre and silent failures on the MAX_PATH issue. This should be considered as a candidate diagnosis if the longest path in the project repository reaches 260 char, but should also be considered even if the project paths (from project root) are themselves short, but the absolute path where the project is checked out (or where the build outputs are placed) consists of a long path.