[CMake] Weird @<< in compile_commands.json

[Martin Weber]

Hi,

I see cmake producing a compile_commands.json file that contains a weird 
expression like '@<< /TP -DECAL_LAYER_FASTRTPS <<'.
This expression causes an issue in my cmake4eclipse project [1].

The expression looks like a commandfile-specifiation, but the file `<<` does 
not exist.

So my question:
Is the '@<< ... <<' just an invention of cmake or is it somehow `official`?

Martin

[1] https://github.com/15knots/cmake4eclipse/issues/93#issuecomment-437783515

-- 
Cd wrttn wtht vwls s mch trsr.