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25 lines
963 B
25 lines
963 B
5 years ago
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This error type is reported only in Objective-C. It is similar to Null
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dereference, but Infer hasn't found a whole trace where the error can happen,
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but only found that a null dereference can happen if you call a method with nil
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as an argument. Therefore it is only a warning. For example:
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```objectivec
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-(int) foo:(A* a) {
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B b* = [a foo]; // sending a message with receiver nil returns nil
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return b->x; // dereferencing b, potential NPE if you pass nil as the argument a.
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}
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```
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or when the parameter is a block:
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```objectivec
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-(void) foo:(void (^)(BOOL))block {
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block(YES); // calling a nil block will cause a crash.
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}
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```
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Possible solutions are adding a check for `nil`, or making sure that the method
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is not called with `nil`. When an argument will never be `nil`, you can add the
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annotation `nonnull` to the argument's type, to tell Infer (and the type
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system), that the argument won't be `nil`. This will silence the warning.
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