https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70529
--- Comment #5 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to jos...@codesourcery.com from comment #4)
> On Tue, 5 Apr 2016, manu at gcc dot gnu.org wrote:
>
> > According to the manual, if an extension is not incompatible with the base
> > standard, it should not be disabled:
>
> In general, this extension *is* incompatible with the base standard -
> there are cases where a program is valid with both versions of pp-numbers,
> but with different semantics. See gcc.dg/c90-hexfloat-2.c, for example.
Oh, well, then current status makes sense.
> It should be possible to lex according to the selected standard, but track
> that a pp-token could be a hex float together with the following two
> pp-tokens (+ or - and the exponent with possible suffix) and then handle
> things specially if that sequence of pp-tokens ends up getting converted
> to tokens.
Perhaps something simpler like this could be enough to inform naive users like
me?
Index: expr.c
===================================================================
--- expr.c (revision 233781)
+++ expr.c (working copy)
@@ -568,11 +568,26 @@ cpp_classify_number (cpp_reader *pfile,
{
if (DIGIT_SEP (*str))
SYNTAX_ERROR_AT (virtual_location,
"digit separator adjacent to exponent");
else
- SYNTAX_ERROR_AT (virtual_location, "exponent has no digits");
+ {
+ if (radix == 16 && !CPP_OPTION (pfile, extended_numbers))
+ {
+ const cpp_token *tok2 = cpp_get_token (parse_in);
+ const cpp_token *tok3 = cpp_get_token (parse_in);
+ if ((tok2 == CPP_MINUS || tok2 == CPP_PLUS)
+ && tok3 == CPP_NUMBER)
+ {
+ if (CPP_OPTION (pfile, cplusplus))
+ SYNTAX_ERROR_AT (virtual_location, "hexadecimal
floating constant with signed exponent requires C99");
+ else
+ SYNTAX_ERROR_AT (virtual_location, "hexadecimal
floating constant with signed exponent requires C++1z");
+ }
+ }
+ SYNTAX_ERROR_AT (virtual_location, "exponent has no
digits");
+ }
}
do
{
seen_digit_sep = DIGIT_SEP (*str);
str++;
It would be better to say:
prog.cc:1:10: error: hexadecimal floating constant with signed exponent
requires C++1z
auto d = 0x123p-2;
~~~~~~^~
but I have no idea how to create ranges dynamically in the new rich_loc world.
