[Interest] Fail to compile qt4 on Ubuntu 20.04.

[Hongyi Zhao]

Hi,

Ubuntu 20.04 dropped the qt4 from its official repo, but sometimes I
still want to use it.  So I try to compile it from the source but
failed.  See the info below:

$ wget https://download.qt.io/archive/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz
$ tar -zxvf qt-everywhere-opensource-src-4.8.7.tar.gz
$ cd qt-everywhere-opensource-src-4.8.7
$ ./configure

# The following step failed for Ubuntu 20.04:
$ make -j4
../../include/QtCore/../../src/corelib/tools/qpair.h:62:20: note:
because ‘QPair<int, int>’ has user-provided ‘QPair<T1, T2>& QPair<T1,
T2>::operator=(const QPair<T1, T2>&) [with T1 = int; T2 = int]’
   62 |     QPair<T1, T2> &operator=(const QPair<T1, T2> &other)
      |                    ^~~~~~~~
make[1]: *** [Makefile:18175: .obj/release-shared/qsslsocket_openssl.o] Error 1
make[1]: Leaving directory
'/home/werner/Downloads/qt-everywhere-opensource-src-4.8.7/src/network'
make: *** [Makefile:278: sub-network-make_default-ordered] Error 2

Any hints for this problem?

Regards,
-- 
Hongyi Zhao <hongyi.zhao at gmail.com>