title: Lot of warnings when applying pedantic GCC keys to project in Qt
body: <p><strong>Intro</strong></p>
  <p>Some time ago I find, that pedantic GCC keys are usefull, and can advice me to write cleaner code.
  When I code simple console C++ app and compile it with parameters:</p>
  <pre><code>-Wall -Wextra -pedantic -Weffc++ -Wold-style-cast
  -Wconversion -Winit-self -Wunreachable-code
  </code></pre>
  <p><em>(here is fully documented information about all of them: <a href="http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html" rel="nofollow noreferrer">Options to Request or Suppress Warnings</a>, <a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Dialect-Options.html" rel="nofollow noreferrer">Options Controlling C++ Dialect</a>)</em></p>
  <hr />
  <p><strong>Problem</strong></p>
  <p>Now, I'm using Qt 4.8.4 with MinGW compiler to build apps.
  The problem is that when I add to my <code>.pro</code>-file next lines:</p>
  <pre><code>QMAKE_CXXFLAGS += -Wall -Wextra -pedantic -Weffc++ -Wold-style-cast
  QMAKE_CXXFLAGS += -Wconversion -Winit-self
  </code></pre>
  <p>I got a <strong>lot</strong> of warnings what does from Qt's sources, but not from my sources.</p>
  <hr />
  <p><strong>Example</strong></p>
  <p>Simple Qt GUI project with parameters wrote above in <code>.pro</code>-file gives 517 warnings like:</p>
  <blockquote>
  <p>D:\Qt\4.8.4\src\corelib\global\qglobal.h:981: warning: base class 'struct QIntegerForSize&lt;4&gt;' has a non-virtual destructor [-Weffc++]</p>
  <p>D:\Qt\4.8.4\src\corelib\tools\qpoint.h:174: warning: conversion to 'float' from 'int' may alter its value [-Wconversion]</p>
  <p>...</p>
  </blockquote>
  <p>And so on.</p>
  <hr />
  <p><strong>Question</strong></p>
  <p>How to avoid applying pedantic parameters to Qt's sources, and use that parameters only at my code?</p>