[RFC FS-1069] Implicit yields (allow dropping yield in list, array, sequence and computation expressions)

[dsyme]

Continuation of #6304 from feature branch

This is the implemntation for RFC FS-1069 Implict yields, i.e. the "implicit yields" language suggestion. This allows implicit yield in list, array, sequence and those computation expressions supporting Yield/Combine/Zero/Delay.

See the RFC for notes and discussion

[dsyme]

This is ready up to getting it green

[cartermp]

@dsyme test failure here: https://dev.azure.com/dnceng/public/_build/results?buildId=216204&view=ms.vss-test-web.build-test-results-tab

(side note: love that @brettfo has this level of integration with our tests set up!)

[dsyme]

side note: love that @brettfo has this level of integration with our tests set up!

@brettfo That is amazing!!

@cartermp Shoud be fixed by latest push

[cartermp]

It's not clear why the 7k line FSComp file is being included here. Is this a clean diff?

[dsyme]

It's not clear why the 7k line FSComp file is being included here. Is this a clean diff?

I cleaned up the diff, thanks

[dsyme]

It also introduces names that are not debuggable; these should change.

What were you referring to for this? thanks!

[dsyme]

We had a transient test failure here, of a kind I've not seen before

Error Message:
 System.ObjectDisposedException : The CancellationTokenSource has been disposed.
Stack Trace:
   at System.Threading.CancellationTokenSource.ThrowObjectDisposedException()
   at FSharp.Compiler.SourceCodeServices.Reactor.SetBackgroundOp(FSharpOption`1 bgOpOpt) in D:\a\1\s\src\fsharp\service\Reactor.fs:line 137
   at FSharp.Compiler.SourceCodeServices.BackgroundCompiler.CheckProjectInBackground(FSharpProjectOptions options, String userOpName) in D:\a\1\s\src\fsharp\service\service.fs:line 827
   at FSharp.Compiler.SourceCodeServices.FSharpChecker.StartBackgroundCompile(FSharpProjectOptions options, FSharpOption`1 userOpName) in D:\a\1\s\src\fsharp\service\service.fs:line 1165
   at Microsoft.VisualStudio.FSharp.LanguageService.FSharpLanguageServiceBackgroundRequests_DEPRECATED.ExecuteBackgroundRequest(FSharpBackgroundRequest_DEPRECATED req, IFSharpSource_DEPRECATED source) in D:\a\1\s\vsintegration\src\FSharp.LanguageService\BackgroundRequests.fs:line 269
   at Salsa.Salsa.Privates.SimpleOpenFile.TryExecuteBackgroundRequest(FSharpBackgroundRequest_DEPRECATED pr) in D:\a\1\s\vsintegration\tests\Salsa\Salsa.fs:line 1129
   at Salsa.Salsa.Privates.SimpleOpenFile.OnIdleTypeCheck() in D:\a\1\s\vsintegration\tests\Salsa\Salsa.fs:line 1158
   at Salsa.Salsa.Privates.SimpleOpenFile.OnIdle() in D:\a\1\s\vsintegration\tests\Salsa\Salsa.fs:line 1115
   at Salsa.Salsa.Privates.SimpleVisualStudio.Salsa-Salsa-IVisualStudio-OnIdle() in D:\a\1\s\vsintegration\tests\Salsa\Salsa.fs:line 848
   at Salsa.Salsa.Privates.SimpleVisualStudio.Salsa-Salsa-IVisualStudio-TakeCoffeeBreak() in D:\a\1\s\vsintegration\tests\Salsa\Salsa.fs:line 856
   at UnitTests.TestLib.LanguageService.LanguageServiceBaseTests.CreateSingleFileProject(FSharpList`1 content, FSharpOption`1 references, FSharpOption`1 defines, FSharpOption`1 fileKind, FSharpOption`1 disabledWarnings, FSharpOption`1 fileName) in D:\a\1\s\vsintegration\tests\UnitTests\TestLib.LanguageService.fs:line 325
   at UnitTests.TestLib.LanguageService.LanguageServiceBaseTests.CreateSingleFileProject(String content, FSharpOption`1 references, FSharpOption`1 defines, FSharpOption`1 fileKind, FSharpOption`1 disabledWarnings, FSharpOption`1 fileName) in D:\a\1\s\vsintegration\tests\UnitTests\TestLib.LanguageService.fs:line 287
   at Tests.LanguageService.AutoCompletion.UsingMSBuild.VerifyDotCompListContainAllAtStartOfMarker(String fileContents, String marker, FSharpList`1 list, FSharpOption`1 addtlRefAssy, FSharpOption`1 coffeeBreak)
   at Tests.LanguageService.AutoCompletion.UsingMSBuild.QueryExpression.DotCompletionSystematic1() in D:\a\1\s\vsintegration\tests\UnitTests\LegacyLanguageService\Tests.LanguageService.Completion.fs:line 7604

[dsyme]

@KevinRansom @TIHan Please advise on adding the /langversion checks for this PR. This needs to be done asap, thanks. I can do it, just let me know.

[KevinRansom]

@dsyme, there appears to be some cancellation token issue with Linux. A bunch of meregs have failed because of it..

[KevinRansom]

@dsyme, I had planned to work through all of the PR's doing the langversion change to fgharp47 and fsharp5 is broken at the moment due to some issue with cancellationtokens and linux. Have you seen this failure on a platform other than linux?

stale

[KevinRansom]

Merging, I will add in the langversion support post merge.