When QCanDbcFileParser parses a dbc file encoded in utf-8 which contains signals like these:

SG_ Sig_exmp_Temp : 0|7@1+ (1,0) [0|70] "°C" Vector__XXX
SG_ Sig_GPS_Longitude : 8|8@1- (1E-009,0) [-1.28E-007|1.27E-007] "deg" Vector__XXX

it will produce warnings saying:

"Failed to find signal description in string SG_ Sig_exmp_Temp : 0|7@1+ (1,0) [0|70] \"°C\" Vector__XXX",
"Failed to find signal description in string SG_ Sig_GPS_Longitude : 8|8@1- (1E-009,0) [-1.28E-007|1.27E-007] \"deg\" Vector__XXX" 

and therefore will not be able to recognize these signals processing a QCanBusFrame.

I would argue that the structure of the signal description is correct nevertheless and the signal should be parsed. I am not too sure about how the regex is working and which characters and structure it supports. But it would be interesting to know why it fails exactly.