From: Joel Salomon <JoelCSalomon@Gmail.com>
To: 9fans@cse.psu.edu
Subject: [9fans] cc lexer bug?
Date: Sun, 18 Feb 2007 15:19:42 -0500 [thread overview]
Message-ID: <cd10e193dd8f20c43d30c91b7a8dd4a5@plan9.jp> (raw)
cpu% cat t.c
void foo (void)
{
double d;
d = 08.7;
USED(d);
}
cpu% 8c t.c
t.c:4 syntax error, last name: 8.7
cpu%
This came up as I’m making my lexer for C able to scan numbers. I
tried to understand ken’s code, but it gets very hairy right around
/sys/src/cmd/cc/lex.c:751 — and I think there’s a bug. Or, at least,
an undocumented departure from the ANSI standard; Harbison & Steele
(5E) suggest that “08.7” is a valid floating point constant.
As far as my lexer is concerned (http://www.tip9ug.jp/who/chesky/comp/lex.c,
if anyone cares), it’s using line-at-a-time buffering courtesy of
Brdstr(2), so I’m back to thinking that regcomp(2) + strtod(2) et al.
is the way to go. It won’t handle hex floats, but who cares?
--Joel
next reply other threads:[~2007-02-18 20:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-18 20:19 Joel Salomon [this message]
2007-02-18 21:22 ` erik quanstrom
2007-02-18 22:07 ` Joel Salomon
2007-02-18 22:40 ` erik quanstrom
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