[PATCH] D15463: [Objective-c] Fix a crash
Akira Hatanaka via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 15 15:31:11 PST 2015
On Tue, Dec 15, 2015 at 12:55 PM, Justin Bogner <mail at justinbogner.com>
wrote:
> Akira Hatanaka <ahatanak at gmail.com> writes:
> > On Mon, Dec 14, 2015 at 10:39 AM, Justin Bogner <mail at justinbogner.com>
> > wrote:
> >
> >> Akira Hatanaka via cfe-commits <cfe-commits at lists.llvm.org> writes:
> >> > ahatanak created this revision.
> >> > ahatanak added a subscriber: cfe-commits.
> >> >
> >> > This patch fixes a crash that occurs when __kindof is incorrectly used
> >> > in the type parameter list of an interface. The crash occurs because
> >> > ObjCTypeParamList::back() is called in checkTypeParamListConsistency
> >> > on an empty list:
> >> >
> >> > 00762 diagLoc =
> >> S.getLocForEndOfToken(newTypeParams->back()->getLocEnd());
> >> >
> >> > http://reviews.llvm.org/D15463
> >> >
> >> > Files:
> >> > lib/Parse/ParseObjc.cpp
> >> > test/SemaObjC/kindof.m
> >> >
> >> > Index: test/SemaObjC/kindof.m
> >> > ===================================================================
> >> > --- test/SemaObjC/kindof.m
> >> > +++ test/SemaObjC/kindof.m
> >> > @@ -302,3 +302,13 @@
> >> > void processCopyable(__typeof(getSomeCopyable()) string);
> >> > processCopyable(0); // expected-warning{{null passed to a callee
> that
> >> requires a non-null argument}}
> >> > }
> >> > +
> >> > +// __kinddof cannot be used in parameter list.
> >> > + at interface Array1<T> : NSObject
> >> > + at end
> >> > +
> >> > + at interface I1 : NSObject
> >> > + at end
> >> > +
> >> > + at interface Array1<__kindof I1*>(extensions) // //
> >> expected-error{{expected type parameter name}}
> >> > + at end
> >> > Index: lib/Parse/ParseObjc.cpp
> >> > ===================================================================
> >> > --- lib/Parse/ParseObjc.cpp
> >> > +++ lib/Parse/ParseObjc.cpp
> >> > @@ -603,7 +603,7 @@
> >> > // whether there are any protocol references.
> >> > lAngleLoc = SourceLocation();
> >> > rAngleLoc = SourceLocation();
> >> > - return list;
> >> > + return invalid ? nullptr : list;
> >>
> >> This looks a bit suspicious to me. Since `invalid` is set *way* earlier
> >> in the function, it seems like we should be able to return earlier if
> >> this is correct, and not even call actOnObjCTypeParamList. OTOH, are
> >> there cases where `invalid == true` but list is non-empty? If so, are we
> >> doing the right thing when that happens?
> >>
> >>
> > I'm assuming you meant it should return earlier if this is *incorrect*
> (but
> > let me know if I misunderstood your comment).
>
> I meant, "If `return invalid ? nullptr : list` is correct, then I
> suspect returning nullptr before calling actOnObjCTypeParamList makes
> more sense.
>
> > The only downside to returning nullptr before actOnObjCTypeParamList is
> > called in line 595 is that it won't print the diagnostics that are
> printed
> > in actOnObjCTypeParamList. For example, if the following interface were
> > compiled,
> >
> > @interface I1<T, T, __kindof I2*> NSObject
> > @end
> >
> > actOnObjCTypeParamList could tell the user that parameter "T" was
> > redeclared in addition to printing the error message about __kindof. So
> if
> > we return before it's called, we won't see that error message.
> >
> > When the interface declaration of category extensions1 in the following
> > piece of code is compiled, invalid is set to true and the list is not
> empty
> > (it contains the first two parameters).
> >
> > @interface I1<T1, T2, T3> NSObject
> > @end
> >
> > @interface I1<T, T, __kindof I2*> (extensions1)
> > @end
> >
> > *test3.m:6:23: **error: **expected type parameter name*
> >
> > @interface I6<T1, T2, __kindof I2*> (extensions1)
> >
> > * ^*
> >
> > *test3.m:6:21: **error: **category has too few type parameters (expected
> 3,
> > have 2)*
> >
> > @interface I6<T1, T2, __kindof I2*> (extensions1)
> > It looks like it's doing the right thing, but the second diagnostic
> doesn't
> > seem necessary to me.
>
> I'm not sure I follow exactly which errors are being reported with your
> patch, so maybe this is already working, but what we basically want is
> to only emit errors that are helpful.
>
> That is, if we get the `"T" is a redeclaration` error as well as the
> __kindof error, that's nice, but if we get the `too few type parameters`
> error that's going to be confusing and bad - the user didn't provide too
> few type parameters, but our previous error caused us to see too few.
>
> Basically, we don't ever want to report errors that are the result of
> previous errors, but as long as we don't end up doing that then
> gathering further errors is totally reasonable. Make sense?
>
>
Yes, that makes perfect sense.
The following shows the error messages I see when I compile test case
test3.m:
$ cat test3.m
#import <Foundation/Foundation.h>
@interface I2 : NSObject
@end
@interface I7<T0, T1, T2> : NSObject
@end
@interface I7<T, T, __kindof I2*>(ext2)
@end
@interface I6<T> : NSObject
@end
@interface I6<__kindof I2*>(ext1)
@end
### This patch: it prints the error messages we want to see.
test3.m:9:21: error: expected type parameter name
@interface I7<T, T, __kindof I2*>(ext2)
^
test3.m:9:18: error: redeclaration of type parameter 'T'
@interface I7<T, T, __kindof I2*>(ext2)
~ ^
test3.m:15:15: error: expected type parameter name
@interface I6<__kindof I2*>(ext1)
^
3 errors generated.
### If it returns nullptr before actOnObjCTypeParamList is called: it
doesn't print the "redeclaration of type parameter" error.
test3.m:9:21: error: expected type parameter name
@interface I7<T, T, __kindof I2*>(ext2)
^
test3.m:15:15: error: expected type parameter name
@interface I6<__kindof I2*>(ext1)
^
2 errors generated.
### Trunk: It prints the "too few type parameters" message and it crashes.
test3.m:9:21: error: expected type parameter name
@interface I7<T, T, __kindof I2*>(ext2)
^
test3.m:9:18: error: redeclaration of type parameter 'T'
@interface I7<T, T, __kindof I2*>(ext2)
~ ^
test3.m:9:19: error: category has too few type parameters (expected 3, have
2)
@interface I7<T, T, __kindof I2*>(ext2)
^
test3.m:15:15: error: expected type parameter name
@interface I6<__kindof I2*>(ext1)
^
clang: error: unable to execute command: Segmentation fault: 11
>
> >> }
> >> >
> >> > /// Parse an objc-type-parameter-list.
> >> >
> >> >
> >>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20151215/5d0de8d7/attachment.html>
More information about the cfe-commits
mailing list