[Proposal]: Collection Expressions in `foreach`

[CyrusNajmabadi]

Collection Expressions in foreach

• Specification: https://github.com/dotnet/csharplang/blob/main/proposals/collection-expressions-in-foreach.md
• Discussion: [Proposal Discussion]: Collection Expressions in `foreach` #9740

Summary

Collection Expressions introduced a terse syntax [e1, e2, e3, etc] to create common collection values. This proposal extends their usage to foreach statements, where they can be used directly as the iteration source without requiring an explicit target type, like so:

// Today, developers must write:
foreach (var toggle in new[] { true, false })
{
    RunTestWithFeatureFlag(toggle);
}

// With this proposal, they can write:
foreach (var toggle in [true, false])
{
    RunTestWithFeatureFlag(toggle);
}

Design meetings