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Re: Is this a compiler bug?
- From: David Malcolm <dmalcolm at redhat dot com>
- To: Andrew Pinski <pinskia at gmail dot com>
- Cc: Steve Kargl <sgk at troutmask dot apl dot washington dot edu>, GCC Mailing List <gcc at gcc dot gnu dot org>
- Date: Mon, 22 Sep 2014 10:22:59 -0400
- Subject: Re: Is this a compiler bug?
- Authentication-results: sourceware.org; auth=none
- References: <20140922012346 dot GA4376 at troutmask dot apl dot washington dot edu> <CA+=Sn1nT8by8dUHugr_Ye8TYmSbGS6Axbbmau7d+-d7WCUVPfQ at mail dot gmail dot com> <20140922015627 dot GA4508 at troutmask dot apl dot washington dot edu> <CA+=Sn1=d1uHGWoV=0=vUgjR4f6cJw81JKYOGTYDPOAqwC4VnrA at mail dot gmail dot com> <20140922030836 dot GB4708 at troutmask dot apl dot washington dot edu> <CA+=Sn1=djpGLqFCkptdkwjTWoffvgMseFf7MnzHBrxSQB0rmnA at mail dot gmail dot com>
On Sun, 2014-09-21 at 22:15 -0700, Andrew Pinski wrote:
> On Sun, Sep 21, 2014 at 8:08 PM, Steve Kargl
> <firstname.lastname@example.org> wrote:
> > On Sun, Sep 21, 2014 at 07:57:45PM -0700, Andrew Pinski wrote:
> >> On Sun, Sep 21, 2014 at 6:56 PM, Steve Kargl
> >> <email@example.com> wrote:
> >> > + is a binary operator. 0x3ffe is a hexidecimal-constant according
> >> > to 126.96.36.199 in n1256.pdf. 63 is, of course, a decimal-constant.
> >> This is before tokens happen and during lexing of the program.
> >> e+64 is exponent-part see 188.8.131.52.
> > 184.108.40.206 applies to floating point constant.
> > 220.127.116.11 is for integer constants.
> Nope again, this time from bug 3885:
> Strange as it may seem, the behavior is correct, and mandated by the C
> Standard. 0x00E-0x00A is a single preprocessor token, of type
> pp-number, and it must become a single compiler token, but it can't.
> The gotcha is the `E-' sequence, that makes it seem like the exponent
> notation of floating-point constants.
> Looks like this is a common misunderstood part of C.
If people tend to get this wrong, should we issue a warning for it?