From qtwebengine/tools/qmake/mkspecs/features/functions.prf: > defineTest(isGCCVersionSupported) { > # The below will work for gcc 4.7 and up and also match gcc 5 > greaterThan(QT_GCC_MINOR_VERSION, 6):return(true) > greaterThan(QT_GCC_MAJOR_VERSION, 4):return(true) > skipBuild("Using gcc version "$$QT_GCC_MAJOR_VERSION"."$$QT_GCC_MINOR_VERSION", but at least gcc version 4.7 is required to build Qt WebEngine.") > return(false) > } It appears the value of QT_GCC_*_VERSION is whatever was used to build qtcore and is sourced from /usr/lib64/qt5/mkspecs/qconfig.pri. Apart from the obvious potential for version mismatches, QT_GCC_*_VERSION will not even be defined at all if qtcore was built with clang. Further, if this magic GCC check fails, build silently fails in such a way that portage does not detect so the user ends up with a zero-file qtwebengine installed.
Created attachment 448470 [details] build.log
Created attachment 448472 [details] qconfig.pri
*** Bug 596808 has been marked as a duplicate of this bug. ***
*** Bug 598292 has been marked as a duplicate of this bug. ***
*** Bug 603468 has been marked as a duplicate of this bug. ***
*** Bug 611066 has been marked as a duplicate of this bug. ***
Created attachment 465680 [details, diff] bogus_gcc_check.patch Yeah, I normally compile dev-qt/* using clang, so this GCC check was really not helpful. qtwebengine has other issues that prevent it from compiling with clang, but it does work with gcc-6.3 now.