On 17 November 2016 at 01:51, Carlos Ferreira wrote: > If I use parenthesis instead of brackets ("O_Partial (x, y)"), the > compiler does not complain and everything goes well. Those are braces, not brackets. > My GCC version is 6.2.1 20160830 (GCC) > > > Can anyone explain me this issue and help me to understand it? It's a bug in GCC. It's fixed in the subversion trunk, but I'm not sure when or how it was fixed.