RunImmediate should use RunSynchronously if called on UI thread #11805
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TIHan
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Jul 8, 2021
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Jan 26, 2022
…et#11805) * RunImmediate uses RunSynchronously on UI thread Co-authored-by: Don Syme <donsyme@fastmail.com>
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We added RunImmediate in #11788 and it gives much, much better debug stacks.
However we hadn't realised that in FSharp.Editor this was sometimes being called on the UI thread - notably for GoToDefinition for external sources. This results in a UI hang for this case. Running an async synchronously on the UI thread is not what we want. So we protect against that.
For this case we rename RunImmediate to RunImmediateExceptOnUI.
(RunImmediateExceptOnUI is now effectively the old F# 4.0 spec for RunSynchronously . This got changed in #11142 to check for isThreadPoolThread, which made our stacks originating from Roslyn background threads worse.)