Re: [bug, bisected, -chrisl] Segfault at evaluate.c:341

From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christopher Li <sparse@chrisli.org>
Cc: Hannes Eder <hannes@hanneseder.net>,
	linux-sparse@vger.kernel.org,
	Nicholas Mc Guire <der.herr@hofr.at>
Subject: Re: [bug, bisected, -chrisl] Segfault at evaluate.c:341
Date: Thu, 19 Mar 2009 22:09:06 +0000	[thread overview]
Message-ID: <20090319220906.GG28946@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20090319215250.GF28946@ZenIV.linux.org.uk>

On Thu, Mar 19, 2009 at 09:52:50PM +0000, Al Viro wrote:
> On Thu, Mar 19, 2009 at 01:04:20PM -0700, Christopher Li wrote:
> 
> > We should stop the segfault though. I take a look at it. It seems that
> > there is a SYM_NODE with base_type is NULL. I guess in some of
> > the error path we result in an invalid AST three.
> 
> We are getting some mess with K&R declarations.  Which is bloody likely
> to be my fault; will check.

Yeah...  It's an old b0rken handling of calls for K&R + changes that exposed
that even worse.

Status quo is restored by the patch below, but it's a stopgap - e.g.
void f();
void g(void)
{
	f(0, 0);
}
will warn about extra arguments as if we had void f(void); as sparse had
been doing all along.  B0rken.

Testcase for the segfault is
void f(x, y);
void g(void)
{
	f(0, 0);
}

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/parse.c b/parse.c
index b9b96ba..87f6264 100644
--- a/parse.c
+++ b/parse.c
@@ -2323,6 +2323,7 @@ static struct token *identifier_list(struct token *token, struct symbol *fn)
 		sym->ident = token->ident;
 		token = token->next;
 		sym->endpos = token->pos;
+		sym->ctype.base_type = &incomplete_ctype;
 		add_symbol(list, sym);
 		if (!match_op(token, ',') ||
 		    token_type(token->next) != TOKEN_IDENT ||
