[repo-assist] docs: document known Debug-mode F# compiler bug affecting taskSeq (#473) - #481
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…taskSeq (#473) Documents the upstream F# compiler regression (dotnet/fsharp#20466, fix in progress at dotnet/fsharp#20469) that can silently truncate a taskSeq { } sequence when awaits occur between yields, but only when the consuming project is built in Debug configuration. Not a bug in this library; Release builds are unaffected. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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🤖 This PR was created automatically by Repo Assist, an AI assistant. A human maintainer should review before merging.
What
Adds a Known issues section to
README.mddocumenting an upstream F# compiler regression discovered while investigating #473: Debug builds on recent .NET SDKs (10.0.400+ / F# 10+) can silently truncate ataskSeq { }sequence thatdo!/awaits betweenyields.MoveNextAsyncsimply returnsfalseafter the first await — no exception, no warning.Root cause
This is not a bug in FSharp.Control.TaskSeq:
-c Debug) — Release (-c Release/-p:Optimize=true) always works correctly.TaskSeqBuilder.fs'sBind/WhileAsync/ForcomposeResumableCodevalues.Since this can't be fixed in library source (it's a compiler-lowering issue), documenting it clearly helps users hitting it (like the reporter of #473, whose tests silently passed on only the first item because
dotnet testdefaults to Debug) find a workaround quickly.Change
README.md: new "Known issues" section with a short description, links to the upstream issue/fix PR, and the workaround (build/test in Release).release-notes.txt: added anUnreleasedbullet per repo convention.Test Status
Documentation-only change; no source code modified.
dotnet fantomas . --checkis not applicable (no.fs/.fsxfiles touched). No build or test run required per repo guidelines for docs-only changes.Relates to #473 (does not close it, since the root cause is external to this library).
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