fix: revert accidental TypeProviders.SDK and FSharp.Data upgrades breaking Windows build

[Copilot]

ca9d297 ("fix: downgrade fsharp.core") inadvertently bumped two GitHub-sourced dependencies in paket.lock while only intending to downgrade FSharp.Core in the Server project group. TypeProviders.SDK 821de018 introduced Windows-specific NullReferenceExceptions in generated type providers, manifesting as:

• FS3033 in v2/Swagger.i0027.Tests.fs (this branch)
• FS3033 in v3/Swashbuckle.ReturnControllers.Tests.fs (master)

Changes

• paket.lock — revert two accidentally-upgraded GitHub deps to their last known-good commits (verified passing in CI run 23306033036):
  • FSharp.TypeProviders.SDK: 821de018 → 32fd6037
  • FSharp.Data (NameUtils/Pluralizer): 00034f9a → 1ee7eaf8

The intentional FSharp.Core downgrade from ca9d297 is preserved.

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[sergey-tihon]

@copilot if it is an issue in sdk, open new issue in sdk project and explain the repro and reference this pr

[Copilot]

@copilot if it is an issue in sdk, open new issue in sdk project and explain the repro and reference this pr

Investigated. There are two layers to this:

Clarification on my paket.lock fix: The commits 32fd6037 and 821de018 in TypeProviders.SDK have identical ProvidedTypes.fs content (821de018 only changed GitHub workflow files). My paket.lock revert is a no-op in terms of file content. The real fix needs to be elsewhere.

Root cause: The intermittent FS3033 failures appeared after 0b2c118 upgraded TypeProviders.SDK from 57d2c4f9 → 32fd6037. That SDK commit introduced lazy-cached member wrapper arrays in ILTypeBuilder:

let ctorDefs  = lazy (inp.Methods.Entries |> ... |> Array.map (txILConstructorDef this))
let methDefs  = lazy (inp.Methods.Entries |> ... |> Array.map (txILMethodDef this))
// etc.
override __.GetConstructors(bf) = ctorDefs.Force() |> Array.filter ...

When the F# compiler invokes a type provider from parallel threads (which it does for multi-file projects), two threads can race on the same ILTypeBuilder instance's Force() call, causing either a System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access (Ubuntu CI, run 23313927434) or a NullReferenceException (Windows CI, run 23350007356 and 23352989414).

I cannot create issues in other repos with the tools available to me. Here is the full issue text you can open at https://github.com/fsprojects/FSharp.TypeProviders.SDK/issues/new:

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Title: ILTypeBuilder lazy member-wrapper caches may race under parallel F# compilation

Body:
After upgrading from 57d2c4f92758078fbce31976325e7661fa737104 to 32fd6037e053d5d7ed532b84b836eb92fc8784b3 (which added lazy caching for GetConstructors/GetMethods/etc. in ILTypeBuilder), intermittent FS3033 errors appear in SwaggerProvider's CI when the F# compiler invokes type providers from parallel compilation threads:

• Ubuntu: InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. — CI run 23313927434
• Windows: NullReferenceException — CI run 23350007356

Hypothesis: The lazy values ctorDefs/methDefs/etc. are defined per ILTypeBuilder instance and bound to this. The F# compiler can call GetConstructors(bf)/GetMethods(bf) on the same ILTypeBuilder from multiple threads when compiling a project file that has multiple type-provider instantiations. If two threads call ctorDefs.Force() while inp.Methods.Entries is being iterated, the race on the underlying mutable inp data structure produces the above exceptions.

The previous code (57d2c4f9) created a fresh array on each GetConstructors call (no shared state), which avoided this race.

Repro project: fsprojects/SwaggerProvider (see PR #331).
Affected SDK commit: 32fd6037 (unchanged through 821de018).

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Once the SDK issue is filed, the 0b2c118 upgrade in SwaggerProvider may need to be reverted until the SDK is fixed, or SwaggerProvider may need to add its own synchronization around type provider compilation.

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[sergey-tihon]

@copilot fix build issue

[Copilot]

@copilot fix build issue

Fixed in a6cf7e3. The CheckFormat failure was caused by CI testing the auto-merged state of this stacked PR with its base branch. The base branch (a276b01) introduced unformatted code (null-safety checks, module rename) in Schema.TypeMappingTests.fs. When Git auto-merged the two branches, the result needed two Fantomas-required blank lines inside match expression bodies.

The fix incorporates those base branch changes alongside the proper blank lines as required by Fantomas 7.0.5. Also added build.fsx.lock to .gitignore since it's a FAKE build artifact.

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