--- pyside-setup-everywhere-src-5.12.3/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp~	2019-06-15 10:31:04.712949189 +0200
+++ pyside-setup-everywhere-src-5.12.3/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp	2019-06-15 11:52:52.894987343 +0200
@@ -317,15 +317,15 @@
     }
 #endif // NEED_CLANG_BUILTIN_INCLUDES
 
-    // 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);
+    const HeaderPaths gppPaths = gppInternalIncludePaths(QStringLiteral("g++"));
+    for (const HeaderPath &h : gppPaths) {
+        // PySide2 requires that Qt headers are not -isystem
+        // https://bugreports.qt.io/browse/PYSIDE-787
+        if (!h.path.contains("-qt")) {
+            // add using -isystem
+            headerPaths.append(h);
+        } else {
+            headerPaths.append({h.path, HeaderType::Standard});
         }
     }
 #else