Fix IL2091 trimming warning in FSharp.Core LazyExtensions.Create (#19114)

Author: Copilot

docs/release-notes/.FSharp.Core/10.0.200.md

@@ -0,0 +1,3 @@
+### Fixed
+
+* Fix IL2091 trimming warning in `LazyExtensions.Create` by adding `DynamicallyAccessedMembers` attribute to the generic type parameter. ([Issue #17356](https://github.com/dotnet/fsharp/issues/17356), [PR #18302](https://github.com/dotnet/fsharp/pull/18302))

src/FSharp.Core/prim-types.fs

@@ -7299,11 +7299,12 @@ namespace Microsoft.FSharp.Core
 namespace Microsoft.FSharp.Control
 
     open System
+    open System.Diagnostics.CodeAnalysis
     open Microsoft.FSharp.Core
     open Microsoft.FSharp.Core.Operators
 
     module LazyExtensions = 
-        type Lazy<'T> with
+        type Lazy<[<DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)>]'T> with
             [<CompiledName("Create")>] // give the extension member a 'nice', unmangled compiled name, unique within this module
             static member Create(creator : unit -> 'T) : Lazy<'T> =
                 let creator = Func<'T>(creator)

src/FSharp.Core/prim-types.fsi

@@ -6144,6 +6144,7 @@ namespace Microsoft.FSharp.Core
 
 namespace Microsoft.FSharp.Control
 
+    open System.Diagnostics.CodeAnalysis
     open Microsoft.FSharp.Core
 
     /// <summary>Extensions related to Lazy values.</summary>
@@ -6152,7 +6153,7 @@ namespace Microsoft.FSharp.Control
     [<AutoOpen>]
     module LazyExtensions =
 
-        type System.Lazy<'T> with
+        type System.Lazy<[<DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)>]'T> with
 
             /// <summary>Creates a lazy computation that evaluates to the result of the given function when forced.</summary>
             ///

tests/AheadOfTime/Trimming/Program.fs

@@ -9365,6 +9365,20 @@ module NonStructuralComparisonOverTimeSpanDirect =
     do check "test9407" (NonStructuralComparison.hash 11L) (Operators.hash 11L)
     do check "test9408" (NonStructuralComparison.hash 11UL) (Operators.hash 11UL)
 
+let testLazySimple () =
+    let f23 () = let z = lazy (12345) in z.Force()
+    check "lazy_simple" 12345 (f23())
+
+let testSeqWithTryFinally () =
+    let result = 
+        seq {
+            try
+                yield 1
+                yield 2
+            with
+            | ex -> ()
+        } |> Seq.toList
+    check "seq_try_with" [1; 2] result
 
 [<EntryPoint>]
 let main _ =
@@ -9385,6 +9399,8 @@ let main _ =
     PercentAPublicTests.tests ()
     PercentAInternalTests.tests ()
     ClassWithEvents.testWithEventClass ()
+    testLazySimple ()
+    testSeqWithTryFinally ()
 
     match !failures with 
     | [] -> 

tests/AheadOfTime/Trimming/check.ps1

@@ -1,33 +1,39 @@
-function CheckTrim($root, $tfm, $outputfile, $expected_len) {
+function CheckTrim($root, $tfm, $outputfile, $expected_len, $callerLineNumber) {
     Write-Host "Publish and Execute: ${tfm} - ${root}"
     Write-Host "Expecting ${expected_len} for ${outputfile}"
 
+    $errors = @()
+    $scriptFile = $PSCommandPath
+
     $cwd = Get-Location
     Set-Location (Join-Path $PSScriptRoot "${root}")
     $build_output = dotnet publish -restore -c release -f:$tfm "${root}.fsproj" -bl:"../../../../artifacts/log/Release/AheadOfTime/Trimming/${root}_${tfm}.binlog"
     Set-Location ${cwd}
     if ($LASTEXITCODE -ne 0)
     {
-        Write-Error "Build failed with exit code ${LASTEXITCODE}"
-        Write-Error "${build_output}" -ErrorAction Stop
+        $errors += "Build failed with exit code ${LASTEXITCODE}"
+        Write-Host "##vso[task.logissue type=error;sourcepath=${scriptFile};linenumber=${callerLineNumber}]Build failed for ${root} with exit code ${LASTEXITCODE}"
+        return $errors
     }
 
     $process = Start-Process -FilePath $(Join-Path $PSScriptRoot "${root}\bin\release\${tfm}\win-x64\publish\${root}.exe") -Wait -NoNewWindow -PassThru -RedirectStandardOutput $(Join-Path $PSScriptRoot "output.txt")
 
     # Checking that the test passed
     $output = Get-Content $(Join-Path $PSScriptRoot output.txt)
     $expected = "All tests passed"
-    if ($LASTEXITCODE -ne 0)
+    if ($process.ExitCode -ne 0)
     {
-        Write-Error "Test failed with exit code ${LASTEXITCODE}" -ErrorAction Stop
+        $errors += "Test failed with exit code $($process.ExitCode)"
+        Write-Host "##vso[task.logissue type=error;sourcepath=${scriptFile};linenumber=${callerLineNumber}]Test execution failed for ${root} with exit code $($process.ExitCode)"
     }
-    if ($output -eq $expected)
+    elseif ($output -ne $expected)
     {
-        Write-Host "Test passed"
+        $errors += "Test failed with unexpected output: Expected '${expected}', Actual '${output}'"
+        Write-Host "##vso[task.logissue type=error;sourcepath=${scriptFile};linenumber=${callerLineNumber}]Test failed for ${root} with unexpected output: Expected '${expected}', Actual '${output}'"
     }
     else
     {
-        Write-Error "Test failed with unexpected output:`nExpected:`n`t${expected}`nActual`n`t${output}" -ErrorAction Stop
+        Write-Host "Test passed"
     }
 
     # Checking that the trimmed outputfile binary is of expected size (needs adjustments if test is updated).
@@ -39,24 +45,46 @@ function CheckTrim($root, $tfm, $outputfile, $expected_len) {
     }
     elseif ($file_len -ne $expected_len)
     {
-        Write-Error "Test failed with unexpected ${tfm}  -  trimmed ${outputfile} length:`nExpected:`n`t${expected_len} Bytes`nActual:`n`t${file_len} Bytes`nEither codegen or trimming logic have changed. Please investigate and update expected dll size or report an issue." -ErrorAction Stop
+        $errors += "Test failed with unexpected ${tfm} - trimmed ${outputfile} length: Expected ${expected_len} Bytes, Actual ${file_len} Bytes"
+        Write-Host "##vso[task.logissue type=error;sourcepath=${scriptFile};linenumber=${callerLineNumber}]Trimmed ${outputfile} size mismatch for ${root}: Expected ${expected_len} Bytes, Actual ${file_len} Bytes. Either codegen or trimming logic have changed. Please investigate and update expected dll size or report an issue."
     }
 
     $fileBeforePublish = Get-Item (Join-Path $PSScriptRoot "${root}\bin\release\${tfm}\win-x64\${outputfile}")
     $sizeBeforePublish = $fileBeforePublish.Length
     $sizeDiff = $sizeBeforePublish - $file_len
     Write-Host "Size of ${tfm} - ${outputfile} before publish: ${sizeBeforePublish} Bytes, which means the diff is ${sizeDiff} Bytes"
+
+    return $errors
 }
 
 # NOTE: Trimming now errors out on desktop TFMs, as shown below:
 # error NETSDK1124: Trimming assemblies requires .NET Core 3.0 or higher.
 
+$allErrors = @()
+
 # Check net9.0 trimmed assemblies
-CheckTrim -root "SelfContained_Trimming_Test" -tfm "net9.0" -outputfile "FSharp.Core.dll" -expected_len 300032
+$allErrors += CheckTrim -root "SelfContained_Trimming_Test" -tfm "net9.0" -outputfile "FSharp.Core.dll" -expected_len 311296 -callerLineNumber 66
 
 # Check net9.0 trimmed assemblies with static linked FSharpCore
-CheckTrim -root "StaticLinkedFSharpCore_Trimming_Test" -tfm "net9.0" -outputfile "StaticLinkedFSharpCore_Trimming_Test.dll" -expected_len 9154048
+$allErrors += CheckTrim -root "StaticLinkedFSharpCore_Trimming_Test" -tfm "net9.0" -outputfile "StaticLinkedFSharpCore_Trimming_Test.dll" -expected_len 9169408 -callerLineNumber 69
 
 # Check net9.0 trimmed assemblies with F# metadata resources removed
-CheckTrim -root "FSharpMetadataResource_Trimming_Test" -tfm "net9.0" -outputfile "FSharpMetadataResource_Trimming_Test.dll" -expected_len 7607296
+$allErrors += CheckTrim -root "FSharpMetadataResource_Trimming_Test" -tfm "net9.0" -outputfile "FSharpMetadataResource_Trimming_Test.dll" -expected_len 7609344 -callerLineNumber 72
+
+# Report all errors and exit with failure if any occurred
+if ($allErrors.Count -gt 0) {
+    Write-Host ""
+    Write-Host "============================================"
+    Write-Host "TRIMMING TESTS FAILED"
+    Write-Host "============================================"
+    Write-Host "Total errors: $($allErrors.Count)"
+    foreach ($err in $allErrors) {
+        Write-Error $err
+    }
+    exit 1
+}
 
+Write-Host ""
+Write-Host "============================================"
+Write-Host "ALL TRIMMING TESTS PASSED"
+Write-Host "============================================"