221767 2021-02-11 11:53:02 -0800 Investigate creation and use of checked_objc_cast<> 2021-02-18 11:53:14 -0800 1 1 1 Unclassified WebKit Web Template Framework WebKit Nightly Build Unspecified Unspecified NEW https://bugs.webkit.org/show_bug.cgi?id=221428 InRadar P2 Normal --- 1 ddkilzer webkit-unassigned darin webkit-bug-importer oldest_to_newest 1728207 0 ddkilzer 2021-02-11 11:53:02 -0800 Investigate creation and use of checked_objc_cast<>. Via Darin Adler (paraphrasing): The dynamic_objc_cast<> method exists, but there may be some cases in WebKit where we actually want a checked_objc_cast<> method, similar to checked_cf_cast<>. In a nutshell: - Use checked_objc_cast<> if we always expect the same type of object (or nil), and it's obviously incorrect if a different (non-nil) object is referenced. - Use dynamic_objc_cast<> if we're checking for a particular type, but it's not fatal if we get a different type. The result of dynamic_objc_cast<> should always be nil-checked. See also the discussion in Bug 221428 Comment #0 for the differences between checked_cf_cast<> and dynamic_cf_cast<>: <https://bugs.webkit.org/show_bug.cgi?id=221428#c0> 1728218 1 darin 2021-02-11 12:05:42 -0800 Because Objective-C has built in predictable behavior for nil, it’s probably a little less common to *need* the stricter checking than in CF code and checked_cf_cast, but I think I spotted a few cases where the runtime check and abort of the "checked" version would be better than what we have right now. 1730960 2 webkit-bug-importer 2021-02-18 11:53:14 -0800 <rdar://problem/74488150>