No warning when using nonnull?

Question

With code like this:

- (nonnull NSString *)testing {
    return nil;
}

Shouldn't I get a compiler warning? I get no warning all, which seems to make the entire nullability stuff seem useless?

Answer 1

Well, in my opinion it should produce a warning, but I couldn't figure out to get one either.

What might be helpful though, is using Product > Analyze to run the CLANG Static Analyzer. This should give the following hint:

Null is returned from a method that is expected to return a non-null value

Another thing worth mentioning is the setting CLANG_WARN_NULLABLE_TO_NONNULL_CONVERSION which is named Incorrect Uses of Nullable values in the Apple LLVM 7.1 - Warnings - All languages section of the Build Settings.

This setting will not produce a warning for incorrect return values, but it shows a warning when using the method with incorrect parameters (e.g. nil for nonnull parameters).

This answer refers to Xcode Version 7.3.1 (7D1014)