Conditionalize null ptr check when casting #35100
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Background: We've noticed a lot of problems from Obj-C APIs that returned null even though they were declared to never do so. These mismatches subvert Swift's type system and can lead to hard-to-diagnose crashes much later in the program. This fatal error was introduced into the primary casting function to help catch such problems closer to the point where they occur so developers could more easily identify and fix them. However, there's been some concern about what this means for old binaries, so we're considering a check here that would allow the old behavior in certain cases yet to be determined. This PR adds the framework for such a check. Resolves rdar://72323929
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@swift-ci Please test and merge |
mikeash
approved these changes
Dec 15, 2020
| destTypeName.c_str(), destType, | ||
| ""); | ||
| } else { | ||
| swift::warning(/* flags = */ 0, msg, |
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This might end up firing too often, if this ends up getting hit in a loop or something. I don't think you need to do this yet, but in the future this may need a flag or count to limit how many times the warning is logged in a given process.
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@swift-ci Please test and merge |
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Background: We've noticed a lot of problems from Obj-C APIs that returned null
even though they were declared to never do so. These mismatches subvert Swift's
type system and can lead to hard-to-diagnose crashes much later in the program.
This fatal error was introduced into the primary casting function to help catch
such problems closer to the point where they occur so developers could more
easily identify and fix them.
However, there's been some concern about what this means for old binaries, so
we're considering a check here that would allow the old behavior in certain
cases yet to be determined. This PR adds the framework for such a check.
Resolves rdar://72323929