10.4. Traditional warnings
10.4 Traditional warnings
You can request warnings about features that did not exist, or worked differently, in traditional C with the -Wtraditional
option. GCC does not warn about features of ISO C which you must use when you are using a conforming compiler, such as the ‘#
’ and ‘##
’ operators.
Presently -Wtraditional
warns about:
- Macro parameters that appear within string literals in the macro body. In traditional C macro replacement takes place within string literals, but does not in ISO C.
- In traditional C, some preprocessor directives did not exist. Traditional preprocessors would only consider a line to be a directive if the ‘
#
’ appeared in column 1 on the line. Therefore-Wtraditional
warns about directives that traditional C understands but would ignore because the ‘#
’ does not appear as the first charact