The current 1.0.3.1-r1 ebuild of pecl-uploadprogress has the following in the ebuild: USE_PHP="php5-5 php5-4" We should add php5-6 to this list as php-5.6 has been in portage for many months now. I have been running pecl-uploadprogress with USE_PHP="php5-5 php5-6" for some weeks now and can confirm that it builds and runs just fine with the newer version of php.
+*pecl-uploadprogress-1.0.3.1-r2 (29 Apr 2015) + + 29 Apr 2015; Brian Evans <grknight@gentoo.org> + +pecl-uploadprogress-1.0.3.1-r2.ebuild: + Revbump to make deps more specific and add php5-6 for bug 545672