Chore :: Remove #IF NULLABLE, MaybeNull and other leftovers from bootstrap times of Nullable feature#19235
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Chore :: Remove #IF NULLABLE, MaybeNull and other leftovers from bootstrap times of Nullable feature#19235
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Remove all #if BUILDING_WITH_LKG || BUILD_FROM_SOURCE conditionals from prim-types.fsi (7 blocks), prim-types.fs (2 blocks), event.fsi (2 blocks), and event.fs (2 blocks). For each block, kept the #else branch which includes: - IsError=true in CompilerMessage attributes (prim-types.fsi) - 'not null' type constraints on delegate types (all files) These conditionals were only needed during F# 9 development when the shipped .NET SDK didn't yet understand NRT. Now that NRT is stable, this code can be unconditionally included.
- Update NullnessShims.fs: nullSafeEquality and NonEmptyString now use 'T | null - Update lib.fs/fsi: dispose and DisposablesTracker.Register use 'T | null - Update illib.fs: reportTime and DelayInitArrayMap use nullable types - Update FileSystem.fs: isInvalidPath/Filename/Directory use pattern matching - Update Activity.fs: escapeStringForCsv and appendWithLeadingComma use nullable - Update Cancellable.fs: Using member uses _ | null - Update LruCache.fs: removeCollected uses nullable LinkedListNode - Minor formatting fix in event.fs (fantomas) Note: Cancellable.fsi retains MaybeNull in signature for backwards compatibility with consuming code (changing it causes FS3261 nullness errors downstream). The MaybeNull type alias is kept in NullnessShims.fs for this purpose.
Replace all MaybeNull<'T> usages with the canonical 'T | null syntax in FSharp.Build implementation files: - Fsc.fs: 33 replacements - Fsi.fs: 11 replacements - FSharpCommandLineBuilder.fs: 2 method signature replacements - WriteCodeFragment.fs: 2 replacements The MaybeNull type definition is retained for backward compatibility. Type annotations added to match expressions returning null to ensure proper type inference with nullable types.
- Remove unused MaybeNull type alias definition from FSharpCommandLineBuilder.fs - Remove unused (^) null-propagation operator from NullnessShims.fs - Inline (^) usage in fsi.fs with direct null check pattern - All FSharp.Build files now use 'T | null syntax directly
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abonie
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Jan 22, 2026
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The BUILDING_WITH_LKG constant was left behind after dotnet#19235 removed all the #if conditionals that referenced it. It's now defined but never used anywhere in the source. Remove it from both props files.
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