32 lines
1.1 KiB
Markdown
32 lines
1.1 KiB
Markdown
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## Enumerable.Empty<TResult> always returns cached instance
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### Scope
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Edge
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### Version Introduced
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4.5
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### Source Analyzer Status
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Available
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### Change Description
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Beginning in .NET 4.5, `Enumerable.Empty` always returns a cached internal instance `IEnumerable<T>`.
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Previously, `Enumerable.Empty` would cache an empty `IEnumerable<T>` at the time the API was called, meaning that in some conditions in which `Enumerable.Empty` was called rapidly and concurrently, different instances of the type could be returned for different calls to the API.
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- [ ] Quirked
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- [ ] Build-time break
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### Recommended Action
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Because the previous behavior was non-deterministic, code is unlikely to depend on it. However, in the unlikely case that empty enumerables are being compared and expected to sometimes be unequal, explicit empty arrays should be created (`new T[0]`) instead of using `Enumerable.Empty`.
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### Affected APIs
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* ```M:System.Linq.Enumerable.Empty``1```
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### Category
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LINQ
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[More information](https://msdn.microsoft.com/en-us/library/hh367887(v=vs.110).aspx#sql)
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<!-- breaking change id: 42 -->
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