cent OS/conda forge: fatal error: 'type_traits' file not found

On the conda-forge Linux image shiboken fails to add the gcc include dirs and compiling pyside fails with:

fatal error: 'type_traits' file not found

Looking at compilersupport.cpp, we are using centos 6.10 with a custom clang 8.0.0, so the logic centos|redhat>=7,<8 is not verified and checkProductVersion returns false, so needsGppInternalHeaders returns false:

// Append the c++ include paths since Clang is unable to find <list> etc
 // on RHEL 7 with g++ 6.3 or CentOS 7.2.
 // A fix for this has been added to Clang 5.0, so, the code can be removed
 // once Clang 5.0 is the minimum version.
 if (needsGppInternalHeaders()) {
 const HeaderPaths gppPaths = gppInternalIncludePaths(QStringLiteral("g++"));
 for (const HeaderPath &h : gppPaths) {
 if (h.path.contains("c++"))
 headerPaths.append(h);
 }
 }

Maybe that logic isnt tied to the os nor clang version ?

But that's not the only problem; if I force needsGppInternalHeaders to return true.

Then it fails on another unfound header: features.h, this c header is not found because of the h.path.contains("c++") filter, so I had to use:

 if (h.path.contains("c++") || h.path.contains("sysroot"))

Another problem is the name of the compiler, it defaults to "g+" but we're using a custom g+ 7.3.0 named x86_64-conda_cos6-linux-gnu-c++,

so I used an env var:

QString cxx = QString::fromLocal8Bit(qgetenv("CXX"));
 if (cxx.isEmpty()) cxx = QStringLiteral("g++");

One could also use CMAKE_C_COMPILER, maybe that's even better.
 
 
One last problem is the os name comparison that must use lowercase conversion, as productType returns "CentOS":
 

const QString &productType = QSysInfo::productType().toLower();
if (productType == QLatin1String("rhel"))
 return LinuxDistribution::RedHat;
if (productType == QLatin1String("centos"))
  return LinuxDistribution::CentOs;