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Re: preprocessor/10613: Please make -Wtrigraphs the default


Neil Booth <neil@daikokuya.co.uk> writes:

> This is a patch for preprocessor/10613 and preprocessor/10614.  We warn
> about trigraphs, unless an explicit -trigraphs (or -std implying
> -trigraphs) is given.  -Wall still implies -Wtrigraphs.

Looks good.  The only thing I have to say is that this bit of
documentation

> This option is in effect unless trigraphs are turned on, and is
> implied by @option{-Wall}.  With the exception of a trigraph that
> would form an escaped newline, warnings are not given for trigraphs
> within comments as they do not affect the meaning of the program.

is confusing.  I would say instead

  Most trigraphs in comments cannot affect the meaning of the program.
  However, a trigraph that would form an escaped newline (@samp{??/}
  at the end of a line) can, by changing where the comment begins or
  ends.  Therefore, only trigraphs that would form escaped newlines
  produce warnings inside a comment.

  This option is implied by @option{-Wall}.  If @option{-Wall} is not
  given, this option is still enabled unless trigraphs are enabled.
  To get trigraph conversion without warnings, but get the other
  @option{-Wall} warnings, use @samp{-trigraphs -Wall -Wno-trigraphs}.

zw


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