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[Bug 1441961] Re: dataChanged signal cannot be used on ARM under certain conditions

 

Can you try to use the old connection syntax? The new syntax is known to
be unreliable on some architectures.

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https://bugs.launchpad.net/bugs/1441961

Title:
  dataChanged signal cannot be used on ARM under certain conditions

Status in qtbase-opensource-src package in Ubuntu:
  New

Bug description:
  This is probably the strangest bug I have ever observed, but it is
  completely reproducible. When running the attached Qt application, I
  receive the following error:

      QObject::connect: signal not found in Test

  This error is 100% reproducible on my Raspberry Pi 2 running Ubuntu
  14.04.2 (Trusty). This device has an ARMv7 CPU (Broadcom BCM2836). I
  cannot reproduce this error on any other hardware (x86 and amd64 have
  been tested). This does not appear to be a compiler bug since both g++
  and Clang produce an executable that prints the above error.

  Here's the thing that really confuses me: the error disappears (and
  everything works correctly) if I comment out the "dataChanged(...)"
  line in test.cpp. This is completely bizarre because the line is never
  executed by any code.

  I've tried digging through Qt's headers and buried myself neck-deep in
  macros, templates, and MOC-generated files. I can't make any sense out
  of this. Therefore I am reporting it as a bug. To compile the example,
  enter the source directory, run "qmake", and then run "make" to build
  the executable. Remember, the bug only manifests itself on an ARM CPU.

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References