[BUG] Transform Feedback + In-Shader specification

Hello everyone,

my question is about OpenGL 4.5 and GL Shading Language 4.50.
I’m trying to specify the transform feedback variables explicitly in the vertexshader source code, but apparently that doesnt work as specified in the GLSL specifications. I stated that problem at opengl.org:

https://www.opengl.org/discussion_boards/showthread.php/199090-Xfer-feedback-variable-optimized-away?p=1284970#post1284970

I assume that the preprocessor optimizes feedback variables away if i use an additional fragment shader. If i remove the fragment shader, ererything works, variables are captured in the transform feedback buffer. But when i add the fragmentshader an pass 1 captureed variable (e.g. the color) to it, the other variable(s) will be discarded (not captured at all).

Best regards