{"action":"created","issue":{"url":"https://api.github.com/repos/dotnet/corefx/issues/33284","repository_url":"https://api.github.com/repos/dotnet/corefx","labels_url":"https://api.github.com/repos/dotnet/corefx/issues/33284/labels{/name}","comments_url":"https://api.github.com/repos/dotnet/corefx/issues/33284/comments","events_url":"https://api.github.com/repos/dotnet/corefx/issues/33284/events","html_url":"https://github.com/dotnet/corefx/issues/33284","id":378055462,"node_id":"MDU6SXNzdWUzNzgwNTU0NjI=","number":33284,"title":"Proposal: MatchFailureException","user":{"login":"gafter","id":3804346,"node_id":"MDQ6VXNlcjM4MDQzNDY=","avatar_url":"https://avatars3.githubusercontent.com/u/3804346?v=4","gravatar_id":"","url":"https://api.github.com/users/gafter","html_url":"https://github.com/gafter","followers_url":"https://api.github.com/users/gafter/followers","following_url":"https://api.github.com/users/gafter/following{/other_user}","gists_url":"https://api.github.com/users/gafter/gists{/gist_id}","starred_url":"https://api.github.com/users/gafter/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gafter/subscriptions","organizations_url":"https://api.github.com/users/gafter/orgs","repos_url":"https://api.github.com/users/gafter/repos","events_url":"https://api.github.com/users/gafter/events{/privacy}","received_events_url":"https://api.github.com/users/gafter/received_events","type":"User","site_admin":false},"labels":[{"id":165998434,"node_id":"MDU6TGFiZWwxNjU5OTg0MzQ=","url":"https://api.github.com/repos/dotnet/corefx/labels/api-ready-for-review","name":"api-ready-for-review","color":"5319e7","default":false},{"id":174276033,"node_id":"MDU6TGFiZWwxNzQyNzYwMzM=","url":"https://api.github.com/repos/dotnet/corefx/labels/area-System.Runtime","name":"area-System.Runtime","color":"d4c5f9","default":false}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":{"url":"https://api.github.com/repos/dotnet/corefx/milestones/21","html_url":"https://github.com/dotnet/corefx/milestone/21","labels_url":"https://api.github.com/repos/dotnet/corefx/milestones/21/labels","id":3242632,"node_id":"MDk6TWlsZXN0b25lMzI0MjYzMg==","number":21,"title":"3.0","description":".NET Core 3.0, next major release after 2.1. See [official release dates](https://github.com/dotnet/core/blob/master/roadmap.md) for details.\r\n\r\nWe will move important issues from Future to 3.0 as the priorities and dates for next release become more clear.","creator":{"login":"karelz","id":5776068,"node_id":"MDQ6VXNlcjU3NzYwNjg=","avatar_url":"https://avatars2.githubusercontent.com/u/5776068?v=4","gravatar_id":"","url":"https://api.github.com/users/karelz","html_url":"https://github.com/karelz","followers_url":"https://api.github.com/users/karelz/followers","following_url":"https://api.github.com/users/karelz/following{/other_user}","gists_url":"https://api.github.com/users/karelz/gists{/gist_id}","starred_url":"https://api.github.com/users/karelz/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/karelz/subscriptions","organizations_url":"https://api.github.com/users/karelz/orgs","repos_url":"https://api.github.com/users/karelz/repos","events_url":"https://api.github.com/users/karelz/events{/privacy}","received_events_url":"https://api.github.com/users/karelz/received_events","type":"User","site_admin":false},"open_issues":335,"closed_issues":2544,"state":"open","created_at":"2018-04-04T16:40:10Z","updated_at":"2018-11-15T01:17:58Z","due_on":"2019-03-31T07:00:00Z","closed_at":null},"comments":4,"created_at":"2018-11-06T22:11:24Z","updated_at":"2018-11-15T01:55:59Z","closed_at":null,"author_association":"MEMBER","body":"## Rationale\r\n\r\nIn order to facilitate the language feature at https://github.com/dotnet/csharplang/issues/45, which has been approved by the LDM and mostly implemented, we should add the exception `MatchFailureException` to the framework.  This exception is to be thrown when no branch of a pattern-matching switch expression matches the input at runtime.\r\n\r\n## Proposal\r\n\r\n```cs\r\nnamespace System\r\n{\r\n    /// <summary>\r\n    /// Indicates that a switch expression that was non-exhaustive failed to match its input\r\n    /// at runtime, e.g. in the C# 8 expression <code>3 switch { 4 => 5 }</code>\r\n    /// </summary>\r\n    [System.Runtime.InteropServices.ComVisible(true)]\r\n    [Serializable]\r\n    public class MatchFailureException : InvalidOperationException\r\n    {\r\n        public MatchFailureException();\r\n        public MatchFailureException(object unmatchedValue);\r\n        public object UnmatchedValue { get; }\r\n    }\r\n}\r\n```\r\n\r\nSee also https://github.com/dotnet/roslyn/issues/27747\r\n/cc @jcouv @jaredpar "},"comment":{"url":"https://api.github.com/repos/dotnet/corefx/issues/comments/438887352","html_url":"https://github.com/dotnet/corefx/issues/33284#issuecomment-438887352","issue_url":"https://api.github.com/repos/dotnet/corefx/issues/33284","id":438887352,"node_id":"MDEyOklzc3VlQ29tbWVudDQzODg4NzM1Mg==","user":{"login":"gafter","id":3804346,"node_id":"MDQ6VXNlcjM4MDQzNDY=","avatar_url":"https://avatars3.githubusercontent.com/u/3804346?v=4","gravatar_id":"","url":"https://api.github.com/users/gafter","html_url":"https://github.com/gafter","followers_url":"https://api.github.com/users/gafter/followers","following_url":"https://api.github.com/users/gafter/following{/other_user}","gists_url":"https://api.github.com/users/gafter/gists{/gist_id}","starred_url":"https://api.github.com/users/gafter/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gafter/subscriptions","organizations_url":"https://api.github.com/users/gafter/orgs","repos_url":"https://api.github.com/users/gafter/repos","events_url":"https://api.github.com/users/gafter/events{/privacy}","received_events_url":"https://api.github.com/users/gafter/received_events","type":"User","site_admin":false},"created_at":"2018-11-15T01:55:59Z","updated_at":"2018-11-15T01:55:59Z","author_association":"MEMBER","body":"I changed the base type to `InvalidOperationException`."}}
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