On Fri, 17 Aug 2018, Bernd Edlinger wrote:
> Richard Biener wrote:
> > +embedded @code{NUL} characters. However, the
> > +@code{TREE_STRING_LENGTH} always includes a trailing @code{NUL} that
> > +is not part of the language string literal but appended by the front end.
> > +If the string shall not be @code{NUL}-terminated the @code{TREE_TYPE}
> > +is one character shorter than @code{TREE_STRING_LENGTH}.
> > +Excess caracters other than one trailing @code{NUL} character are not
characters btw.
I read the above that the string literal for
char x[2] = "1";
is actually "1\0\0" - there's one NUL that is not part of the language
string literal. The second sentence then suggests that both \0
are removed because 2 is less than 3?
As said, having this extra semantics of a STRING_CST tied to
another tree node (its TREE_TYPE) looks ugly.
> > +permitted.
> >
> > I find this very confusing and oppose to that change. Can we get
> > back to the drawing board please? If we want an easy way to
> > see whether a string is "properly" terminated then maybe we can
> > simply use a flag that gets set by build_string?
> >
>
> What I mean with that is the case like
> char x[2] = "123456";
>
> which is build_string(7, "123456"), but with a type char[2],
> so varasm throws away "3456\0".
I think varasm throws away chars not because of the type of
the STRING_CST but because of the available storage in x.
> I want to say that this is not okay, the excess precision
> should only be used to strip the nul termination, in cases
> where it is intended to be a assembled as a not zero terminated
> string. But maybe the wording could be improved?
ISTR we always assemble a NUL in .strings to get string merging
working.
Richard.
