After calling this function:

QSGMaterialShader::setShaderSourceFile (qsgmaterialshader.cpp:313)

some time later this call chain occurs:

QSGMaterialShaderPrivate::loadShaderSource (qsgmaterialshader.cpp:54)
QSGShaderSourceBuilder::appendSourceFile (qsgshadersourcebuilder.cpp:244)
QFile::open (qfile.cpp:893)
QFilePrivate::engine (qfile.cpp:110)
QAbstractFileEngine::create (qabstractfileengine.cpp:204)
QFileSystemEngine::resolveEntryAndCreateLegacyEngine (qfilesystemengine.cpp:191)
_q_resolveEntryAndCreateLegacyEngine_recursive (qfilesystemengine.cpp:135)

Which leads to this error message:

Failed to find shader "qrc:/scenegraph/graph/shaders/noisy.vsh"
Failed to find shader "qrc:/scenegraph/graph/shaders/noisy.fsh"

There is something going on which does not take "qrc:" prefix into account.

if (ch == QLatin1Char(':')) {
if (prefixSeparator == 0)

Unknown macro: { engine = new QResourceFileEngine(filePath); return _q_checkEntry(engine, resolvingEntry); }

As far as I get it, QResourceFileEngine will be created only for paths starting with ":" because of prefixSeparator == 0 check.

I really wonder, how other things like QML imports and resolved URLs work, while this one doesn't.