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MangelMaximeMangelMaxime
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[JS/TS] Fix Array.zeroCreate producing null for user-defined struct (value type) elements instead of a default-initialized instance (#4423)
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Lines changed: 85 additions & 48 deletions

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‎src/Fable.Cli/CHANGELOG.md‎

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@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
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### Fixed
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* [JS/TS] Fix `Array.zeroCreate` producing `null` for user-defined struct (value type) elements instead of a default-initialized instance (by @MangelMaxime)
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* [All] Fix interpolated string holes missing format specifiers in State.fs and Python/Replacements.fs (code scanning alerts 1144, 1145, 1512)
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* [Rust] Replace unsafe `.IsSome && .Value` option pattern with `Option.exists` in Fable2Rust.fs (code scanning alert 1125)
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* [JS/TS] Fix `Unchecked.defaultof<char>` being emitted as `null` instead of `'\0'` (by @MangelMaxime)

‎src/Fable.Compiler/CHANGELOG.md‎

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@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
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### Fixed
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* [JS/TS] Fix `Array.zeroCreate` producing `null` for user-defined struct (value type) elements instead of a default-initialized instance (by @MangelMaxime)
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* [All] Fix interpolated string holes missing format specifiers in State.fs and Python/Replacements.fs (code scanning alerts 1144, 1145, 1512)
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* [Rust] Replace unsafe `.IsSome && .Value` option pattern with `Option.exists` in Fable2Rust.fs (code scanning alert 1125)
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* [JS/TS] Fix `Unchecked.defaultof<char>` being emitted as `null` instead of `'\0'` (by @MangelMaxime)

‎src/Fable.Transforms/Replacements.fs‎

Lines changed: 72 additions & 48 deletions
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@@ -673,7 +673,54 @@ let makeHashSet (com: ICompiler) ctx r t sourceSeq =
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makeEqualityComparer com ctx key |> makeHashSetWithComparer com r t sourceSeq
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| _ -> Helper.GlobalCall("Set", t, [ sourceSeq ], isConstructor = true, ?loc = r)
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let rec getZero (com: ICompiler) (ctx: Context) (t: Type) =
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let tryEntityIdent (com: Compiler) entFullName =
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match entFullName with
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| BuiltinDefinition BclDateOnly
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| BuiltinDefinition BclDateTime
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| BuiltinDefinition BclDateTimeOffset -> makeIdentExpr "Date" |> Some
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| BuiltinDefinition BclTimer -> makeImportLib com Any "default" "Timer" |> Some
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| BuiltinDefinition(FSharpReference _) -> makeImportLib com Any "FSharpRef" "Types" |> Some
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| BuiltinDefinition(FSharpResult _) -> makeImportLib com Any "FSharpResult$2" "Result" |> Some
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| BuiltinDefinition(FSharpChoice genArgs) ->
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let membName = $"FSharpChoice${List.length genArgs}"
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makeImportLib com Any membName "Choice" |> Some
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// | BuiltinDefinition BclGuid -> jsTypeof "string" expr
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// | BuiltinDefinition BclTimeSpan -> jsTypeof "number" expr
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// | BuiltinDefinition BclHashSet _ -> fail "MutableSet" // TODO:
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// | BuiltinDefinition BclDictionary _ -> fail "MutableMap" // TODO:
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// | BuiltinDefinition BclKeyValuePair _ -> fail "KeyValuePair" // TODO:
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// | BuiltinDefinition FSharpSet _ -> fail "Set" // TODO:
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// | BuiltinDefinition FSharpMap _ -> fail "Map" // TODO:
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| Types.matchFail -> makeImportLib com Any "MatchFailureException" "Types" |> Some
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| Types.exception_ -> makeImportLib com Any "Exception" "Util" |> Some
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| "System.OperationCanceledException" -> makeImportLib com Any "OperationCanceledException" "AsyncBuilder" |> Some
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| "System.Collections.Generic.KeyNotFoundException" ->
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makeImportLib com Any "KeyNotFoundException" "System.Collections.Generic"
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|> Some
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| BuiltinSystemException entName -> makeImportLib com Any entName "System" |> Some
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// | Naming.EndsWith "Exception" _ -> makeImportLib com Any "Exception" "Util" |> Some
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| Types.attribute -> makeImportLib com Any "Attribute" "Types" |> Some
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| "System.Uri" -> makeImportLib com Any "Uri" "Uri" |> Some
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| "Microsoft.FSharp.Control.FSharpAsyncReplyChannel`1" ->
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makeImportLib com Any "AsyncReplyChannel" "AsyncBuilder" |> Some
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| "Microsoft.FSharp.Control.FSharpEvent`1" -> makeImportLib com Any "Event" "Event" |> Some
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| "Microsoft.FSharp.Control.FSharpEvent`2" -> makeImportLib com Any "Event$2" "Event" |> Some
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| "Microsoft.FSharp.Core.CompilerServices.ListCollector`1" ->
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makeImportLib com Any "ListCollector$1" "FSharp.Core.CompilerServices" |> Some
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| _ -> None
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let tryConstructor com (ent: Entity) =
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if FSharp2Fable.Util.isReplacementCandidate ent.Ref then
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tryEntityIdent com ent.FullName
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else
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FSharp2Fable.Util.tryEntityIdentMaybeGlobalOrImported com ent
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let constructor com ent =
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match tryConstructor com ent with
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| Some e -> e
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| None -> $"Cannot find %s{ent.FullName} constructor" |> addErrorAndReturnNull com [] None
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let rec private getZero (com: ICompiler) (ctx: Context) (t: Type) =
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match t with
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| Boolean -> makeBoolConst false
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| Char -> makeCharConst '\000'
@@ -686,6 +733,30 @@ let rec getZero (com: ICompiler) (ctx: Context) (t: Type) =
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| Builtin(FSharpSet genArg) as t -> makeSet com ctx None t "Empty" [] genArg
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| Builtin(BclKeyValuePair(k, v)) -> makeTuple None true [ getZero com ctx k; getZero com ctx v ]
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| ListSingleton(CustomOp com ctx None t "get_Zero" [] e) -> e
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| DeclaredType(entRef, _) ->
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let ent = com.GetEntity(entRef)
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// For user-defined value types (structs), call the constructor with zero values
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// for each instance field so Array.zeroCreate produces properly initialized instances
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// instead of null. Only instance fields are constructor parameters; static fields
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// (from `static let` bindings) are not, and iterating them could cause deep recursion
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// through static field type graphs.
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if ent.IsValueType then
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tryConstructor com ent
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|> Option.map (fun e ->
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let args =
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ent.FSharpFields
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|> List.choose (fun f ->
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if f.IsStatic then
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None
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else
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getZero com ctx f.FieldType |> Some
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)
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Helper.ConstructorCall(e, t, args)
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)
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|> Option.defaultValue (Value(Null Any, None)) // null
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else
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Value(Null Any, None) // null
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| _ -> Value(Null Any, None) // null
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let getOne (com: ICompiler) (ctx: Context) (t: Type) =
@@ -911,53 +982,6 @@ let injectArg (com: ICompiler) (ctx: Context) r moduleName methName (genArgs: Ty
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| None -> args
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| Some injectInfo -> injectArgInner args injectInfo
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914-
let tryEntityIdent (com: Compiler) entFullName =
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match entFullName with
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| BuiltinDefinition BclDateOnly
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| BuiltinDefinition BclDateTime
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| BuiltinDefinition BclDateTimeOffset -> makeIdentExpr "Date" |> Some
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| BuiltinDefinition BclTimer -> makeImportLib com Any "default" "Timer" |> Some
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| BuiltinDefinition(FSharpReference _) -> makeImportLib com Any "FSharpRef" "Types" |> Some
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| BuiltinDefinition(FSharpResult _) -> makeImportLib com Any "FSharpResult$2" "Result" |> Some
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| BuiltinDefinition(FSharpChoice genArgs) ->
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let membName = $"FSharpChoice${List.length genArgs}"
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makeImportLib com Any membName "Choice" |> Some
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// | BuiltinDefinition BclGuid -> jsTypeof "string" expr
926-
// | BuiltinDefinition BclTimeSpan -> jsTypeof "number" expr
927-
// | BuiltinDefinition BclHashSet _ -> fail "MutableSet" // TODO:
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// | BuiltinDefinition BclDictionary _ -> fail "MutableMap" // TODO:
929-
// | BuiltinDefinition BclKeyValuePair _ -> fail "KeyValuePair" // TODO:
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// | BuiltinDefinition FSharpSet _ -> fail "Set" // TODO:
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// | BuiltinDefinition FSharpMap _ -> fail "Map" // TODO:
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| Types.matchFail -> makeImportLib com Any "MatchFailureException" "Types" |> Some
933-
| Types.exception_ -> makeImportLib com Any "Exception" "Util" |> Some
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| "System.OperationCanceledException" -> makeImportLib com Any "OperationCanceledException" "AsyncBuilder" |> Some
935-
| "System.Collections.Generic.KeyNotFoundException" ->
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makeImportLib com Any "KeyNotFoundException" "System.Collections.Generic"
937-
|> Some
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| BuiltinSystemException entName -> makeImportLib com Any entName "System" |> Some
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// | Naming.EndsWith "Exception" _ -> makeImportLib com Any "Exception" "Util" |> Some
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| Types.attribute -> makeImportLib com Any "Attribute" "Types" |> Some
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| "System.Uri" -> makeImportLib com Any "Uri" "Uri" |> Some
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| "Microsoft.FSharp.Control.FSharpAsyncReplyChannel`1" ->
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makeImportLib com Any "AsyncReplyChannel" "AsyncBuilder" |> Some
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| "Microsoft.FSharp.Control.FSharpEvent`1" -> makeImportLib com Any "Event" "Event" |> Some
945-
| "Microsoft.FSharp.Control.FSharpEvent`2" -> makeImportLib com Any "Event$2" "Event" |> Some
946-
| "Microsoft.FSharp.Core.CompilerServices.ListCollector`1" ->
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makeImportLib com Any "ListCollector$1" "FSharp.Core.CompilerServices" |> Some
948-
| _ -> None
949-
950-
let tryConstructor com (ent: Entity) =
951-
if FSharp2Fable.Util.isReplacementCandidate ent.Ref then
952-
tryEntityIdent com ent.FullName
953-
else
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FSharp2Fable.Util.tryEntityIdentMaybeGlobalOrImported com ent
955-
956-
let constructor com ent =
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match tryConstructor com ent with
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| Some e -> e
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| None -> $"Cannot find %s{ent.FullName} constructor" |> addErrorAndReturnNull com [] None
960-
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let tryOp com r t op args =
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Helper.LibCall(com, "Option", "tryOp", t, op :: args, ?loc = r)
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‎tests/Js/Main/ArrayTests.fs‎

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Original file line numberDiff line numberDiff line change
@@ -45,6 +45,11 @@ type Things =
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type Animal = Duck of int | Dog of int
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[<Struct>]
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type MyStruct(value: int, flag: bool) =
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member _.Value = value
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member _.Flag = flag
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let tests =
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testList "Arrays" [
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testCase "Pattern matching with arrays works" <| fun () ->
@@ -240,6 +245,12 @@ let tests =
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equal 0. a.[1].Key
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equal false a.[2].Value
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testCase "Array.zeroCreate works with struct" <| fun () ->
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let arr = Array.zeroCreate<MyStruct> 3
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equal 0 arr.[0].Value
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equal false arr.[0].Flag
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equal 3 arr.Length
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testCase "Array.create works" <| fun () ->
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let xs = Array.create 2 5
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equal 2 xs.Length

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