Umm... shouldn't this behavior be commented so that people are not left wondering why it fails and trying to "fix" it?
On Wed, Nov 10, 2010 at 16:04, Darin Adler <da...@apple.com> wrote: > On Nov 10, 2010, at 2:33 PM, Daebarkee Jung wrote: > > > I found that the following lines made errors: > > // OwnPtrCommon.h > > template <typename T> inline void deleteOwnedPtr(T* ptr) > > { > > typedef char known[sizeof(T) ? 1 : -1]; > > if (sizeof(known)) > > delete ptr; > > } > > > > I am very curious about why the author wrote like the above. > > What could be the author's intention? > > The code is to prevent issues like the ones described on these websites: > > http://stackoverflow.com/questions/1767679/incomplete-type-memory-leaks > > http://bytes.com/topic/c/answers/611877-gcc-class-forward-declarations-destructor-calls > > http://connect.microsoft.com/VisualStudio/feedback/details/231177/delete-of-pointer-to-incomplete-class > > If we delete a pointer and the object has incomplete type, we get undefined > behavior. Instead this code causes compilation to fail if the object has > incomplete type. The use of a negative number for the size of an array is a > way to guarantee we get a compilation error. > > Your alternate version might also work; I’m not sure. > > -- Darin > > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev >
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