Hi, Author,
you can find the necessary information in the documentation (https://dev.opencascade.org/doc/overview/html/occt_dev_guides__upgrade.html)
Upgrade to OCCT 7.0.0
Porting of user applications from an earlier OCCT version to version 7.0.0 requires taking into account the following major changes.
Building OCCT now requires compiler supporting some C++11 features. The supported compilers are:
MSVC: version 10 (Visual Studio 2010) or later
GCC: version 4.3 or later
CLang: version 3.6 or later
ICC: version XE 2013 SP 1 or later
When compiling code that uses OCCT with GCC and CLang compilers, it is necessary to use compiler option -std=c++0x (or its siblings) to enable C++11 features.
Regards,
Dima