Messages in this thread | | | Date | Wed, 28 May 2003 07:16:37 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: sparse errors |
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On Wed, 28 May 2003, Ryan Anderson wrote: > > I'm not totally grokking how sparse is put together yet, but I've got > this: > > Some symbols with type SYM_NODE are getting ctype->base_type==NULL,
This means they have no type at all, either because of a parse error, or because the lazy evaluation hasn't evaluated it yet (ie it was a tad _too_ lazy).
> causing a segfault in type_difference:422. (If I work around that one, > there's another spot at line 680. I started to follow what was going on > a bit at that point and realized they were probably symptoms, not the > actual bug, so I stopped working around it.)
Right.
The first thing to do is to see where it happens, in gdb do
up (to get to compatible_assignment_types) p expr->pos (to get where in the soruce file it is)
it's triggered in cramfs_uncompress_block():
zlib_inflateReset(&stream);
on "stream", and the problem _seems_ to be that the target type for the function call comparison is non-existent.
And that, in turn, seems to be because of the old K&R style function prototype due to
#ifndef OF /* function prototypes */ # ifdef STDC # define OF(args) args # else # define OF(args) () # endif #endif
and check not defining STDC.
It appears to be fixed by just adding -DSTDC to the check command line, to make zlib use ANSI prototypes.
In short: sparse doesn't handle K&R function declarations very well, although clearly it shouldn't have segfaulted (it should have warned about it). I don't know why it didn't warn.
> Oh, BTW, the way you have struct ctype_sym declared inside struct symbol > confuses the crap out of gdb, but gcc appears to like it, so... *shrug*.
Yeah, gdb is crap when it comes to anonymous structures, but I can't live without them these days, so..
> Should this be cc:ed to linux-kernel, or do you have another place in > mind?
It probably shouldn't be CC'd to linux-kernel, but there isn't any other place either.
Linus
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