[Bug preprocessor/23479] Implement binary constants with a "0b" prefix

[j at uriah dot heep dot sax dot de]

------- Additional Comments From j at uriah dot heep dot sax dot de  2005-08-19 13:57 -------
(In reply to comment #2)

> Confirmed, note I would actually disable binary constants by default
> instead of what the patch currently does, pedwarns about them.

Curious: why?

There are more than two dozen GCC language extensions enabled by
default, most of them would allow GCC to accept a program that will
not be accepted by a different compiler.  E.g., I'd consider most
targets silently accepting dollar signs in identifiers to be at least
similarly or even more dangerous.

I simply followed the established practice in my suggested
implementation.

> Or maybe pedwarn about them by default with an option to turn off
> that pedwarn.

That would equally apply to about all extension.  I'd rather suggest
to have something like -Wgcc-extensions, and perhaps include that by
default into -Wall.  This would make anyone aware of the GCC
extensions used in their applications.  Differentiating between
``good'' and ``not so good'' GCC extensions seems to be a bit strange
to me.  Maybe two levels of GCC extension warnings would be
appropriate, so any extension keywords starting with two underscores
would only be warned at an additional level (-Wall-gcc-extensions, or
perhaps only by -pedantic), as these have been used by the developers
deliberately.  (That should cover any case of __attribute__,
__inline__, __asm__ and such being implicitly used by operating system
headers, etc.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23479