Info Node: (cpp-300.info)Miscellaneous obsolete features
(cpp-300.info)Miscellaneous obsolete features
Miscellaneous obsolete features
-------------------------------
Here are a few more obsolete features.
* Attempting to paste two tokens which together do not form a valid
preprocessing token.
The preprocessor currently warns about this and outputs the two
tokens adjacently, which is probably the behavior the programmer
intends. It may not work in future, though.
Most of the time, when you get this warning, you will find that
`##' is being used superstitiously, to guard against whitespace
appearing between two tokens. It is almost always safe to delete
the `##'.
* `#pragma poison'
This is the same as `#pragma GCC poison'. The version without the
`GCC' prefix is deprecated. Note:Pragmas.
* Multi-line string constants
GCC currently allows a string constant to extend across multiple
logical lines of the source file. This extension is deprecated
and will be removed in a future version of GCC. Such string
constants are already rejected in all directives apart from
`#define'.
Instead, make use of ISO C concatenation of adjacent string
literals, or use `\n' followed by a backslash-newline.