NEW 221767
Investigate creation and use of checked_objc_cast<> 
https://bugs.webkit.org/show_bug.cgi?id=221767
Summary Investigate creation and use of checked_objc_cast<>
David Kilzer (:ddkilzer)
Reported 2021-02-11 11:53:02 PST
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>
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Add attachment proposed patch, testcase, etc.
Darin Adler
Comment 1 2021-02-11 12:05:42 PST
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.
Radar WebKit Bug Importer
Comment 2 2021-02-18 11:53:14 PST
<rdar://problem/74488150>
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