In gcc I got: 1.c:1:11: warning: trigraph ??< ignored, use -trigraphs to enable [-Wtrigraphs] Is there a preprocessor directive to enable support out of c

In gcc I got: 1.c:1:11: warning: trigraph ??< ignored, use -trigraphs to enable [-Wtrigraphs] Is there a preprocessor directive to enable support out of curiosity?