{"action":"created","issue":{"url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/510","labels_url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/510/labels{/name}","comments_url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/510/comments","events_url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/510/events","html_url":"https://github.com/fsharp/FSharp.Compiler.Service/issues/510","id":126256526,"number":510,"title":"FCS + PowerTools breaking F# Formatting","user":{"login":"tpetricek","id":485413,"avatar_url":"https://avatars.githubusercontent.com/u/485413?v=3","gravatar_id":"","url":"https://api.github.com/users/tpetricek","html_url":"https://github.com/tpetricek","followers_url":"https://api.github.com/users/tpetricek/followers","following_url":"https://api.github.com/users/tpetricek/following{/other_user}","gists_url":"https://api.github.com/users/tpetricek/gists{/gist_id}","starred_url":"https://api.github.com/users/tpetricek/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/tpetricek/subscriptions","organizations_url":"https://api.github.com/users/tpetricek/orgs","repos_url":"https://api.github.com/users/tpetricek/repos","events_url":"https://api.github.com/users/tpetricek/events{/privacy}","received_events_url":"https://api.github.com/users/tpetricek/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2016-01-12T19:30:50Z","updated_at":"2016-01-13T19:00:56Z","closed_at":null,"body":"I seem to be repeatedly getting into issues when I update F# Formatting to use a new version of Visual F# PowerTools and F# Compiler service. \r\n\r\nMost recently, I started getting the following error when referencing F# Formatting from the FsSnip project (https://github.com/tpetricek/FsSnip.Website):\r\n\r\n    System.TypeInitializationException: The type initializer for '<StartupCode$FSI_0001>.$FSI_0001_App$fsx' threw an exception. ---> \r\n    System.TypeInitializationException: The type initializer for 'FSI_0001.FsSnip.Snippet' threw an exception. ---> \r\n    System.TypeInitializationException: The type initializer for '<StartupCode$FSI_0001>.$FSI_0001_FsSnip.Snippet' threw an exception. ---> \r\n    System.TypeInitializationException: The type initializer for 'FSI_0001.FsSnip.Utils' threw an exception. ---> \r\n    System.TypeInitializationException: The type initializer for '<StartupCode$FSI_0001>.$FSI_0001_FsSnip.Utils' threw an exception. ---> \r\n    System.MissingMethodException: Method not found: 'Void Microsoft.FSharp.Compiler.SourceCodeServices.FSharpChecker.set_ImplicitlyStartBackgroundWork(Boolean)'.\r\n   at FSharpVSPowerTools.LanguageService..ctor(FSharpOption`1 backgroundCompilation, FSharpOption`1 projectCacheSize, FSharpOption`1 fileSystem)\r\n\r\nIt was only happening inside Azure (I was suspecting wrong F# Core reference?) but it started working when I downgraded F# Compiler service to 1.4.2 (see [this change](https://github.com/tpetricek/FsSnip.Website/commit/db9fc7fbf9712a0d3515f75a44a7f605e17c2ee2#diff-b27553841b4413a24ed1b9aff865105bL7)). I do not really see why, because the method exists in the newest version too and it does not reference any F# Core types.\r\n\r\nI think there might be more general issue here though because `FSharpVSPowerTools.Core` package references `FSharp.Compiler.Service (≥ 1.4.2)`, but I think what it really means is that it needs _exactly_ `1.4.2` because newer versions of F# Compiler Service often break compatibility.\r\n\r\n@matthid @dsyme @vasily-kirichenko @dungpa What should we do here?\r\n\r\nShould F# Compiler Service not have breaking changes within sub-versions? Or should PowerTools have a fixed-version dependency? Or am I missing something?\r\n"},"comment":{"url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/comments/171398476","html_url":"https://github.com/fsharp/FSharp.Compiler.Service/issues/510#issuecomment-171398476","issue_url":"https://api.github.com/repos/fsharp/FSharp.Compiler.Service/issues/510","id":171398476,"user":{"login":"matthid","id":1866463,"avatar_url":"https://avatars.githubusercontent.com/u/1866463?v=3","gravatar_id":"","url":"https://api.github.com/users/matthid","html_url":"https://github.com/matthid","followers_url":"https://api.github.com/users/matthid/followers","following_url":"https://api.github.com/users/matthid/following{/other_user}","gists_url":"https://api.github.com/users/matthid/gists{/gist_id}","starred_url":"https://api.github.com/users/matthid/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/matthid/subscriptions","organizations_url":"https://api.github.com/users/matthid/orgs","repos_url":"https://api.github.com/users/matthid/repos","events_url":"https://api.github.com/users/matthid/events{/privacy}","received_events_url":"https://api.github.com/users/matthid/received_events","type":"User","site_admin":false},"created_at":"2016-01-13T19:00:56Z","updated_at":"2016-01-13T19:00:56Z","body":"Without actually reproducing anything this is probaly in fact another instance of tpetricek/FSharp.Formatting#337 and there is no bug here at FCS.\r\n\r\n@tpetricek while you downgraded FCS you also upgraded FAKE from [4.4.1 bundling FCS 1.4.0.1](https://github.com/fsharp/FAKE/blob/4.4.1/paket.lock#L20) to [4.14.0 bundling FCS 1.4.2.1](https://github.com/fsharp/FAKE/blob/4.14.0/paket.lock#L19). Note that 1.4.0.1 doesn't contain the method while 1.4.2.1 does. You can simply verify this by unlocking FCS in the paket.dependences file and after updating FCS it should still work.\r\n\r\n@forki Thank you for giving us lockfiles :+1: \r\n\r\nRelated https://github.com/fsprojects/Paket/issues/1381 its definitly a problem across all the three projects (FAKE, Paket, FSF)"}}