From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <lucvoo@kernel.org>,
Sparse Mailing-list <linux-sparse@vger.kernel.org>
Subject: Re: [PATCH] allow show_token() on TOKEN_ZERO_IDENT
Date: Tue, 7 Jun 2022 22:48:12 +0200 [thread overview]
Message-ID: <20220607204812.g7kvxkdlz247ddf3@mail> (raw)
In-Reply-To: <CAHk-=wjYBPYsD-h_KkOG2zZTEXQ3yYEOzD_S83mnJqXjs1tcrQ@mail.gmail.com>
On Tue, Jun 07, 2022 at 11:26:36AM -0700, Linus Torvalds wrote:
> On Tue, Jun 7, 2022 at 5:55 AM Luc Van Oostenryck <lucvoo@kernel.org> wrote:
> >
> > TOKEN_ZERO_IDENTs are created during the evaluation of pre-processor
> > expressions but which otherwise are normal idents and were first tokenized
> > as TOKEN_IDENTs.
> >
> > As such, they could perfectly be displayed by show_token() but are not.
> > So, in error messages they are displayed as "unhandled token type '4'",
> > which is not at all informative.
> >
> > Fix this by letting show_token() process them like usual TOKEN_IDENTs.
> > Idem for quote_token().
>
> Ack.
>
> I do wonder if it should be marked somehow as being that special case.
> The main reason for 'show_token()' is debugging, after all, and
> TOKEN_ZERO_IDENT does have magical properties in how it either
> silently expands to the constant '0', or it generates a warning about
> undefined preprocessor symbol.
>
> But considering that we've apparently reported it as "unhandled token
> type '4'" since 2005, I guess it's not exactly a big deal.
Yes, I first thought to do so but then choose not because I could not
convince myself that its special property was irrelevant in warning/error
messages. It looks to me more as an internal thing, more semantical than
lexical, and a non-faithful representation would be confusing in messages.
For context, the input text I had (from GCC's testsuite) was:
#define empty
#if empty#cpu(m68k)
#endif
and the error message sparse issued was:
error: garbage at end: #unhandled token type '4' (unhandled token type '4' )
with this patch it's:
error: garbage at end: #cpu(m68k)
-- Luc
prev parent reply other threads:[~2022-06-08 0:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-07 12:54 [PATCH] allow show_token() on TOKEN_ZERO_IDENT Luc Van Oostenryck
2022-06-07 18:26 ` Linus Torvalds
2022-06-07 20:48 ` Luc Van Oostenryck [this message]
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