On Tue, Dec 15, 2015 at 12:55 PM, Justin Bogner <m...@justinbogner.com> wrote:
> Akira Hatanaka <ahata...@gmail.com> writes: > > On Mon, Dec 14, 2015 at 10:39 AM, Justin Bogner <m...@justinbogner.com> > > wrote: > > > >> Akira Hatanaka via cfe-commits <cfe-commits@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. > >> > +@interface Array1<T> : NSObject > >> > +@end > >> > + > >> > +@interface I1 : NSObject > >> > +@end > >> > + > >> > +@interface Array1<__kindof I1*>(extensions) // // > >> expected-error{{expected type parameter name}} > >> > +@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. > >> > > >> > > >> >
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