Remove a non-useful type check on generic type variable #3457
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This type test was introduced during the null safety migration and I do not see discussion about the intention. In practice this is `assert(true)` so it would be safest to remove it entirely, but we can also take a guess at the intention. The full assert when it was introduced was `asset(T is! Iterable || splitCommas == true)`. Later the second condition was removed, and the `splitCommas` field overridden to always return `false`. I think the intention was to express that options which support multiple values _must_ split commas, and now that this class is only used without splitting commas the intention is that the options must be scalar values. Invert the type test with a value known to satisfy a check for any subtype of `Iterable`. Add a string explaining the assert.
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This wouldn't catch cases where the type variable is bound to cc @lrhn WDYT? |
lrhn
reviewed
Jun 29, 2023
lib/src/dartdoc_options.dart
Outdated
| @@ -597,7 +597,8 @@ class DartdocOptionArgSynth<T> extends DartdocOption<T> | |||
| String help = '', | |||
| OptionKind optionIs = OptionKind.other, | |||
| this.negatable = false}) | |||
| : assert(T is! Iterable), | |||
| : assert(const <Never>[] is! T, | |||
| '$T should not be bound to a type which allows iterables'), | |||
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This would indeed allow T to be Set, which is iterable.
To check whether T is/is not a subtype of Iterable, you need to put T on the LHS of the is check, e.g., <T>[] is! List<Iterable>.
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But... the comment says to not allow any type which allows an iterable. That suggests not allowingObject either.
In practice any non-final type may allow an iterable, so I wouldn't try to do anything for that.
natebosch
changed the title
srawlins
approved these changes
Dec 27, 2023
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This type test was introduced during the null safety migration and I do
not see discussion about the intention.
In practice this is
assert(true)so it is safe to remove.I think the intention was to express that options which support multiple
values must split commas, and now that this class is only used without
splitting commas the intention is that the options must be scalar
values.
It is not easy to perform this type of test on a type variable, so remove it.