[Repo Assist] Monthly Activity 2026-03

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Activity for March 2026

Suggested Actions for Maintainer

Comprehensive list of all pending actions requiring maintainer attention:

• Check comment on NullReferenceException when calling a virtual Object method on a value type from inline function #8098: Repo Assist labelled AI-thinks-issue-fixed — NullReferenceException when calling virtual Object method on value type from inline SRTP function — fixed by PR Resolve ILVerify errors — adjust codegen (551 → 56 errors) #19372 (callvirt→call for value types) — verify and close — View
• Check comment on Unexpected warning '[FS3511] This state machine is not statically compilable' #12839: Repo Assist labelled AI-thinks-issue-fixed — FS3511 state machine warning fixed by PR Improve static compilation of state machines #19297 — verify and close — View
• Check comment on Expression tree with anonymous type created incorrectly #11127: Repo Assist labelled AI-thinks-issue-fixed — anonymous record expression tree Lambda.Invoke bug fixed by PR FSharp.Core 'query' related fixes #19243 — verify and close — View
• Check comment on FS0267 trying to concatenate string in an attribute value with --checked+ #11398: Repo Assist labelled AI-thinks-issue-fixed — FS0267 with --checked+ and string concatenation in attribute values now compiles successfully — verify and close — View
• Check comment on Index out of range when building with shipped compiler #14879: Repo Assist labelled AI-thinks-issue-fixed — FS0193 Index was outside bounds in FCS builds reportedly fixed per vzarytovskii (Nov 2024) — verify and close — View
• Check comment on internal error : encodeCustomAttrElemType: unrecognized custom element type #12796: Repo Assist labelled AI-thinks-issue-fixed — encodeCustomAttrElemType: unrecognized custom element type when using generic record type in typeof<> attribute argument — now compiles correctly with Newtonsoft.Json — verify and close — View
• Check comment on sbyte array comparison doesn't work correctly with negative values #5263: Repo Assist labelled as potentially fixed — dsyme commented (2026-03-17) suggesting a regression test should be added — View
• Check comment on Wrong XmlDoc for union case when previous case contains no bar #11488: Repo Assist labelled AI-thinks-issue-fixed — fixed by PR Redesign XmlDoc collecting mechanism #11973 (XmlDoc redesign, merged Sept 2021) — verify and close — View
• Check comment on No description is provided for a completion item with a quote in its name #13194: Repo Assist commented — XPath quote bug fixed in current codebase — verify and close — View
• Check comment on use binding for IAsyncDisposable not supported in F# interactive #14454: Repo Assist labelled AI-thinks-issue-fixed — use for IAsyncDisposable in task CE now works in FSI — verify and close — View
• Check comment on Wrong type accessibility error is not reported for a signature #11331: Repo Assist labelled AI-thinks-issue-fixed — Wrong type accessibility error now correctly reported at compile time (FS0410) — verify and close — View
• Reconsider label on Error using type abbreviation for attribute #7877: Repo Assist labelled AI-thinks-issue-fixed but T-Gro (maintainer) confirmed FS0033 error is still wrong — consider removing the label — View
• Check comment on defaultTraverse for SynPat in SyntaxTraverse.Traverse doesn't walk down all SynPats #13114: Repo Assist labelled AI-thinks-issue-fixed — SynPat.Record and SynPat.QuoteExpr now handled in defaultTraverse — verify and close — View
• Check comment on Later errors obscure earlier errors  #13697: Repo Assist labelled AI-thinks-issue-fixed — typeof(T) in attribute context now correctly shows FS0039 — verify and close — View
• Check comment on internal error: no 'value__' field found for enumeration type when rec module & enum constraint & type alias #14580: Repo Assist labelled AI-thinks-issue-fixed — FS0073: internal error: no 'value__' field found in module rec now replaced with proper FS0033 — verify and close — View
• Check comment on Error number 3217 is reused for two errors  #15655: Repo Assist labelled AI-thinks-issue-fixed — packageManagerError renumbered from 3217 to 999 — verify and close — View
• Check comment on Spurious FS3570 warning with Active Pattern #16410: Repo Assist labelled AI-thinks-issue-fixed — spurious FS3570 warning with Active Pattern fixed by PR Bugfix for DotLambda - (a, (b, c)) was incorrectly detected as a discard (a compiler generated one was there) #16334 — verify and close — View
• Check comment on Symbols API: FSharpEntity.IsByRef is false for byref`1 #3532: Repo Assist labelled AI-thinks-issue-fixed — FSharpEntity.IsByRef now returns true for byref<'T> — verify and close — View
• Check comment on Stress test on type system involving many statically resolved type parameters #9382: Repo Assist labelled AI-thinks-issue-fixed — SRTP stress test (FS0073 internal error) now compiles correctly — verify and close — View
• Check comment on Undefined or unsolved type variable #9878: Repo Assist labelled AI-thinks-issue-fixed — SRTP undefined type variable now resolved correctly — verify and close — View
• Check comment on Units of Measure applied to literal bindings are ignored #6929: Repo Assist labelled AI-thinks-issue-fixed — Units of Measure now preserved on literal bindings — verify and close — View
• Check comment on Finding references / renaming doesn't work for active patterns in signature files #14969: Repo Assist labelled AI-thinks-issue-fixed — finding references/renaming for active patterns in sig files fixed by PR Find All References and Rename Symbol Bug Fixes #19252 — verify and close — View

Additional observations for maintainer's attention

Issue #5263 (sbyte array comparison with negative values gives wrong results) was reportedly fixed in 2018 via PR #5267 but analysis strongly suggests the bug (unsigned comparison instead of signed) is still present — dsyme has indicated a regression test should be added.

Issue #12464 (Green color ascribed to end of a range, and to methods in editor) also affects VS Code/Ionide — a Dec 2025 comment shows reproduction in VS Code. This is cross-platform, not Windows-only.

Issue #14321 (Build fails without feedback when reusing DU constructor and IWSAM member names) is a confirmed bug where IL phase2 produces a "duplicate entry in property table" error with no compile-time diagnostic. As of Jan 2025, a contributor (edgarfgp) is investigating a fix — View.

Issue #12303 (AddBackticksToIdentifierIfNeeded adds ticks for not word) — has a clear, small fix: remove not from keywordsWithDescription in PrettyNaming.fs since not is a library function, not a lexer keyword — View.

Issue #12300 (Values inside as patterns are disposed multiple times — use a as b = d disposes d twice) is confirmed still present — View.

Issue #11929 (Calling protected static base member from static do raises MethodAccessException) — remains open for the default compilation mode (fixed only with --realsig+) — View.

Issue #6379 (FS2014 duplicate tupledArg error on certain multi-arg method calls) — root cause identified: tuple arg handling in overload resolution produces duplicate messages — View.

Issue #13099 (Task CE drops exception in Release mode) — confirmed still present; optimizer eliminates entire task { ... } block including side effects in Release mode — high-impact correctness bug — View.

Issue #5834 (CLIEvent abstract event accessors missing specialname IL flag) — confirmed still present; GenAbstractBinding in IlxGen.fs doesn't call .WithSpecialName for abstract event add_X/remove_X methods, violating CLI spec CLS Rule 29 — View.

Signature generation roundtrip gap: Issues #14308, #14310, and #13810 form a cluster: signature generation (--sig) doesn't emit [(Sealed)]/[(Class)] for OO-style types (#14308), doesn't include private fields for structs (#14310), and doesn't preserve literal names in attribute arguments (#13810). All three remain open and unfixed.

Issue #6110 (Incorrect error message when mixing struct/reference anonymous records) — error message says "One tuple type is a struct tuple, the other is a reference tuple" instead of mentioning anonymous records. Small fix: update tcTupleStructMismatch error message in FSComp.txt — View.

Issue #8353 (Internal error when using optional attribute parameter without DefaultParameterValue for bool) — GenAttribArg in IlxGen.fs handles Const.Bool but not Const.Zero for bool types; DefaultValue fallback generates Const.Zero triggering "The type 'System.Boolean' may not be used as a custom attribute value" — small fix possible — View.

Future Work for Repo Assist

• Continue scanning pre-2023 bug issues (cursor at ~project with type provider builds in VS but not with "dotnet build" #10323, 2020-10 vintage)

Run History

2026-03-21 04:53 UTC — Run

• 🔍 Scanned pre-2023 bugs pages 1-3 (~150 issues from 2018–2020, cursor to ~project with type provider builds in VS but not with "dotnet build" #10323); no new fixed/Windows-only candidates found
• 🔍 Confirmed still-open: Struct member access inside quotation gives compile error  #6293 (struct quotation), Error constructing struct record in member using 'with' #7536 (struct with copy), Incorrect error message when mixing struct/reference anonymous records #6110 (anon record error msg), Internal error when using custom attribute and omitting optional argument #8353 (optional bool in attribute), No "implementation missing" error for abstract override #7776 (abstract override)
• 📝 Added observations about easy-fix candidates: Incorrect error message when mixing struct/reference anonymous records #6110, Internal error when using custom attribute and omitting optional argument #8353

2026-03-21 04:08 UTC — Run

• 🔍 Scanned final batch of pre-2023 bugs (cursor [Automated] PRs inserted in VS build main-33031.09 #14200 → nativeptr in interfaces leads to runtime errors #14508); no new fixed/Windows-only candidates found; cursor wraps back to start for next run

2026-03-21 03:29 UTC — Run

• 🔍 Scanned pre-2023 bugs (~200 issues, cursor to ~[Automated] PRs inserted in VS build main-33031.09 #14200); no new fixed bugs found
• 🔍 Confirmed [<CLIEvent>] on abstract type member generates accessor methods without specialname #5834 (CLIEvent abstract event accessors missing specialname flag in GenAbstractBinding) still present via code analysis

2026-03-21 00:44 UTC — Run

• 🏷️ Labelled Wrong type accessibility error is not reported for a signature #11331 with AI-thinks-issue-fixed — Wrong type accessibility error now correctly reported at compile time as FS0410
• 💬 Commented on Wrong type accessibility error is not reported for a signature #11331 with fix analysis
• 🔍 Scanned 2021–2022 pre-2023 bugs; tested ~20 additional repros; most confirmed still present

2026-03-20 23:37 UTC — Run

• 🏷️ Labelled NullReferenceException when calling a virtual Object method on a value type from inline function #8098 with AI-thinks-issue-fixed — NullReferenceException when calling virtual method on value type via SRTP fixed by PR Resolve ILVerify errors — adjust codegen (551 → 56 errors) #19372
• 💬 Commented on NullReferenceException when calling a virtual Object method on a value type from inline function #8098 with fix analysis

2026-03-20 22:38 UTC — Run

• 🔍 Scanned ~25 pre-2023 bugs via recently-merged PRs; all referenced bugs already closed or confirmed still present

2026-03-20 21:37 UTC — Run

• 🏷️ Labelled Finding references / renaming doesn't work for active patterns in signature files #14969 with AI-thinks-issue-fixed — Finding references/renaming for active patterns in sig files fixed by PR Find All References and Rename Symbol Bug Fixes #19252
• 💬 Commented on Finding references / renaming doesn't work for active patterns in signature files #14969

2026-03-20 17:38 UTC — Run

• 🏷️ Labelled Unexpected warning '[FS3511] This state machine is not statically compilable' #12839 with AI-thinks-issue-fixed — FS3511 state machine warning fixed by PR Improve static compilation of state machines #19297
• 🏷️ Labelled Expression tree with anonymous type created incorrectly #11127 with AI-thinks-issue-fixed — anonymous record expression tree bug fixed by PR FSharp.Core 'query' related fixes #19243

2026-03-20 16:39 UTC — Run

• 🔍 Cycle 4: scanned ~30 more pre-2023 bug issues; no new fixed bugs found

2026-03-20 15:40 UTC — Run

• 🔍 Cycle 3: scanned ~100 pre-2023 bug issues across 2019–2022 range

2026-03-20 12:40 UTC — Run

• 🔍 Completed pre-2023 bug scan — verified still present: Incorrect error message when mixing struct/reference anonymous records #6110, [<Literal>] references fail in recursive modules #6338, Error constructing struct record in member using 'with' #7536, NullReferenceException when calling a virtual Object method on a value type from inline function #8098, Empty array as default parameter doesn't work as expected #10117, Compile error from field vs submodule name ambiguity when outside unopened module #10444, Working list of F# version of Roslyn feature APIs to open up #11238, Cubic/Exponential compilation time for very large anonymous record #11638, Incorrect error message with applicative Computation Expressions  #12607, Stack overflow typechecking large CEs on macOS #13084

2026-03-20 11:37 UTC — Run

• 🔍 Continued pre-2023 bug scan from Use GetFullPath when determining the full path in command line options #7376 through ~Support IDE0049 in F# #14541

2026-03-20 09:39 UTC — Run

• 🏷️ Labelled FS0267 trying to concatenate string in an attribute value with --checked+ #11398 with AI-thinks-issue-fixed — FS0267 with --checked+ now compiles in latest SDK

2026-03-20 08:39 UTC — Run

• 🔍 Pre-2023 scan; no new candidates; verified still present: internal error : encodeCustomAttrElemType: unrecognized custom element type #12796, defaultTraverse for SynPat in SyntaxTraverse.Traverse doesn't walk down all SynPats #13114, Problem consuming C# API with default value for parameter #13519

2026-03-20 07:13 UTC — Run

• 🏷️ Labelled internal error : encodeCustomAttrElemType: unrecognized custom element type #12796 with AI-thinks-issue-fixed
• 💬 Commented on internal error : encodeCustomAttrElemType: unrecognized custom element type #12796

2026-03-20 05:17 UTC — Run

• 🏷️ Labelled Index out of range when building with shipped compiler #14879 with AI-thinks-issue-fixed
• 💬 Commented on Index out of range when building with shipped compiler #14879

2026-03-19 21:35 UTC — Run

• 🏷️ Labelled Wrong XmlDoc for union case when previous case contains no bar #11488 with AI-thinks-issue-fixed
• 💬 Commented on Wrong XmlDoc for union case when previous case contains no bar #11488

2026-03-19 19:26 UTC — Run

• 🏷️ Labelled Units of Measure applied to literal bindings are ignored #6929 with AI-thinks-issue-fixed
• 💬 Commented on Units of Measure applied to literal bindings are ignored #6929

2026-03-19 17:13 UTC — Run

• 🏷️ Labelled defaultTraverse for SynPat in SyntaxTraverse.Traverse doesn't walk down all SynPats #13114 with AI-thinks-issue-fixed

2026-03-19 15:28 UTC — Run

• 🏷️ Labelled Later errors obscure earlier errors  #13697 with AI-thinks-issue-fixed
• 🏷️ Labelled internal error: no 'value__' field found for enumeration type when rec module & enum constraint & type alias #14580 with AI-thinks-issue-fixed

2026-03-19 13:08 UTC — Run

• 🏷️ Labelled Error number 3217 is reused for two errors  #15655 with AI-thinks-issue-fixed
• 🏷️ Labelled Spurious FS3570 warning with Active Pattern #16410 with AI-thinks-issue-fixed

2026-03-19 10:52 UTC — Run

• 🏷️ Labelled Symbols API: FSharpEntity.IsByRef is false for byref`1 #3532 with AI-thinks-issue-fixed
• 🏷️ Labelled Stress test on type system involving many statically resolved type parameters #9382 with AI-thinks-issue-fixed

2026-03-18 22:01 UTC — Run

• 🏷️ Labelled Undefined or unsolved type variable #9878 with AI-thinks-issue-fixed
• 🏷️ Labelled use binding for IAsyncDisposable not supported in F# interactive #14454 with AI-thinks-issue-fixed

2026-03-18 20:55 UTC — Run

• 🏷️ Labelled No description is provided for a completion item with a quote in its name #13194 with AI-thinks-issue-fixed
• 💬 Commented on No description is provided for a completion item with a quote in its name #13194

2026-03-18 17:07 UTC — Run

• 🏷️ Labelled Error using type abbreviation for attribute #7877 with AI-thinks-issue-fixed (later found incorrect — T-Gro confirmed still wrong)
• 🏷️ Labelled Problem consuming C# API with default value for parameter #13519 with AI-thinks-issue-fixed
• 💬 Commented on Problem consuming C# API with default value for parameter #13519

2026-03-18 14:02 UTC — Run

• 🔍 Initial scan — pre-2023 bug investigation started
• Created this Monthly Activity issue [Repo Assist] Monthly Activity 2026-03 #19439

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2026-03-21 20:37 UTC — Run

• 🔍 Cycle 32: Scanned 2022 tail ([Automated] PRs inserted in VS build main-33110.21 #14290–nativeptr in interfaces leads to runtime errors #14508), 2021 H2 (Go to Metadata for extension methods displays extended class or interface instead of extension class #11765–MissingFieldException when assigning to a function pointer field #12551), and scattered 2019–2020 bugs
• 🔍 Confirmed still-present: Bitwise or on a char enum should error at compile time #11785 (char enum bitwise ||| runtime crash), Confusing/incorrect type mismatch message in async CE #14437 (async CE confusing type mismatch message), nativeptr in interfaces leads to runtime errors #14508 (nativeptr in interface TypeLoadException), Recursive type with a legal Zero value fails to compile #12379 (recursive type with Zero constraint), Pseudo namespace "global" fails when used with specifying record fields, and acts odd with DU fields #10282 (global namespace in module context), {||} cannot be used as a type #6941 (empty anonymous record as type), No service error for using CompiledName on multiple values #6131 (CompiledName on tuple binding — still internal error)
• 🔍 Issue Mutually recursive non-function values with intermediate module definition not initialized incorrectly #12384 (mutually recursive record values): original simple let rec ... and ... case is fixed (PR Fix 12384: non-nested direct mutrec bindings #12395), but the remaining case with intermediate module inside module rec is still broken
• 🔍 No new AI-thinks-issue-fixed labels applied this run — no cleanly-fixed bugs found in scanned range
• 🔍 Cursor advanced to MissingFieldException when assigning to a function pointer field #12551 (2021-11); next run continues 2021 H2 after MissingFieldException when assigning to a function pointer field #12551

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Run Update: 2026-03-20 20:38 UTC — Run

Cycle 8 – Final scan of pre-2023 bugs complete.

Scanned all remaining unlabeled pre-2023 bugs (21 total). Confirmed the following are still genuine open bugs — no changes needed:

• Generic Record Types have different Equality semantics to concrete types #527 — Generic Record Types have different IStructuralEquatable semantics to concrete types (verified reproducible in current F# SDK)
• Identifiers with '@' symbol generate invalid code #1255 — Identifiers with @ symbol generate invalid code — BarAt returns "bar" instead of "hello" (verified reproducible)
• No message reported when a ProvidedType has an ObsoleteAttribute #897 — No ObsoleteAttribute warning on ProvidedType definitions — TODO: provided attributes comment still in AttributeChecking.fs:140
• Type annotation adjacency warning doesn't consider operator names #774, Illegal prefix operators sometimes compile fine, but give confusing errors when applied #792, No diagnostic when custom attributes ignored on unparenthesized tuple type #462, Enum type is lost when used in attribute #995, Access protected const from base class in attribute #3172, Problem: Unlike C#, the F# compiler allows multiple entries of assembly attributes #3548, Async.DefaultCancellationToken susceptible to memory leaks #3590, fsi reference order matter #3600 — all confirmed genuinely open

Also closed duplicate issue #19438 (older "[Repo Assist] Monthly Activity 2026-03").

All pre-2023 bugs are now fully scanned (8 cycles). Next run: move to post-2023 bugs.

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2026-03-21 09:38 UTC — Run

• 🔍 Cycle 22: Scanned all 10 pages (284 pre-2023 bugs, issues Instantiating a generative type provider twice results in invalid IL #37–nativeptr in interfaces leads to runtime errors #14508) — no new fixed/Windows-only candidates found with high confidence
• 🔍 Checked in detail: Unions with 4 or more cases silently fail to utilize UseNullAsTrueValue. #711 (UseNullAsTrueValue/4+ cases, locked), Duplicate cases in match statement not producing compiler warnings if grouped #3448 (duplicate match cases — by-design OR pattern behavior), Compiler allows us to box a byreflike type, leading to runtime crash #7114 (boxing byreflike — still open), [<CompiledName>] ignored on extension properties #9405 (CompiledName on extension properties — still open), Pseudo namespace "global" fails when used with specifying record fields, and acts odd with DU fields #10282 (global namespace with record fields — still open), Calling op_Addition on primitive types doesn't work #14013 (op_Addition on primitives — labeled Resolution-By Design), Syntax error with string interpolation - Unexpected identifier in binding #14394 (string interpolation syntax error — still open)
• 🔍 Cycle 22 complete — proceeding to Cycle 23 next run

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