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Removing unreachable code (#15281)
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* Removing unreachable code

* Automated command ran: fantomas

  Co-authored-by: T-Gro <46543583+T-Gro@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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T-Gro and github-actions[bot] authored Jun 1, 2023
1 parent 8bed194 commit c4ad09a
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Showing 4 changed files with 5 additions and 116 deletions.
69 changes: 5 additions & 64 deletions src/Compiler/Interactive/fsi.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -4463,8 +4463,6 @@ type FsiEvaluationSession
legacyReferenceResolver: LegacyReferenceResolver option
) =

do UnmanagedProcessExecutionOptions.EnableHeapTerminationOnCorruption() (* SDL recommendation *)

// Explanation: When FsiEvaluationSession.Create is called we do a bunch of processing. For fsi.exe
// and fsiAnyCpu.exe there are no other active threads at this point, so we can assume this is the
// unique compilation thread. For other users of FsiEvaluationSession it is reasonable to assume that
Expand Down Expand Up @@ -4625,9 +4623,9 @@ type FsiEvaluationSession
| Some assembly -> Some(Choice2Of2 assembly)
| None ->
#endif
match tcImports.TryFindExistingFullyQualifiedPathByExactAssemblyRef aref with
| Some resolvedPath -> Some(Choice1Of2 resolvedPath)
| None -> None
match tcImports.TryFindExistingFullyQualifiedPathByExactAssemblyRef aref with
| Some resolvedPath -> Some(Choice1Of2 resolvedPath)
| None -> None

let fsiDynamicCompiler =
FsiDynamicCompiler(
Expand Down Expand Up @@ -4739,68 +4737,11 @@ type FsiEvaluationSession
/// A host calls this to report an unhandled exception in a standard way, e.g. an exception on the GUI thread gets printed to stderr
member x.ReportUnhandledException exn = x.ReportUnhandledExceptionSafe true exn

member _.ReportUnhandledExceptionSafe isFromThreadException (exn: exn) =
member _.ReportUnhandledExceptionSafe _isFromThreadException (exn: exn) =
fsi.EventLoopInvoke(fun () ->
fprintfn fsiConsoleOutput.Error "%s" (exn.ToString())
diagnosticsLogger.SetError()

try
diagnosticsLogger.AbortOnError(fsiConsoleOutput)
with StopProcessing ->
// BUG 664864 some window that use System.Windows.Forms.DataVisualization types (possible FSCharts) was created in FSI.
// at some moment one chart has raised InvalidArgumentException from OnPaint, this exception was intercepted by the code in higher layer and
// passed to Application.OnThreadException. FSI has already attached its own ThreadException handler, inside it will log the original error
// and then raise StopProcessing exception to unwind the stack (and possibly shut down current Application) and get to DriveFsiEventLoop.
// DriveFsiEventLoop handles StopProcessing by suppressing it and restarting event loop from the beginning.
// This schema works almost always except when FSI is started as 64 bit process (FsiAnyCpu) on Windows 7.

// http://msdn.microsoft.com/en-us/library/windows/desktop/ms633573(v=vs.85).aspx
// Remarks:
// If your application runs on a 32-bit version of Windows operating system, uncaught exceptions from the callback
// will be passed onto higher-level exception handlers of your application when available.
// The system then calls the unhandled exception filter to handle the exception prior to terminating the process.
// If the PCA is enabled, it will offer to fix the problem the next time you run the application.
// However, if your application runs on a 64-bit version of Windows operating system or WOW64,
// you should be aware that a 64-bit operating system handles uncaught exceptions differently based on its 64-bit processor architecture,
// exception architecture, and calling convention.
// The following table summarizes all possible ways that a 64-bit Windows operating system or WOW64 handles uncaught exceptions.
// 1. The system suppresses any uncaught exceptions.
// 2. The system first terminates the process, and then the Program Compatibility Assistant (PCA) offers to fix it the next time
// you run the application. You can disable the PCA mitigation by adding a Compatibility section to the application manifest.
// 3. The system calls the exception filters but suppresses any uncaught exceptions when it leaves the callback scope,
// without invoking the associated handlers.
// Behavior type 2 only applies to the 64-bit version of the Windows 7 operating system.

// NOTE: tests on Win8 box showed that 64 bit version of the Windows 8 always apply type 2 behavior

// Effectively this means that when StopProcessing exception is raised from ThreadException callback - it won't be intercepted in DriveFsiEventLoop.
// Instead it will be interpreted as unhandled exception and crash the whole process.

// FIX: detect if current process in 64 bit running on Windows 7 or Windows 8 and if yes - swallow the StopProcessing and ScheduleRestart instead.
// Visible behavior should not be different, previously exception unwinds the stack and aborts currently running Application.
// After that it will be intercepted and suppressed in DriveFsiEventLoop.
// Now we explicitly shut down Application so after execution of callback will be completed the control flow
// will also go out of WinFormsEventLoop.Run and again get to DriveFsiEventLoop => restart the loop. I'd like the fix to be as conservative as possible
// so we use special case for problematic case instead of just always scheduling restart.

// http://msdn.microsoft.com/en-us/library/windows/desktop/ms724832(v=vs.85).aspx
let os = Environment.OSVersion
// Win7 6.1
let isWindows7 = os.Version.Major = 6 && os.Version.Minor = 1
// Win8 6.2
let isWindows8Plus = os.Version >= Version(6, 2, 0, 0)

if
isFromThreadException
&& ((isWindows7 && (IntPtr.Size = 8) && isWindows8Plus))
#if DEBUG
// for debug purposes
&& Environment.GetEnvironmentVariable("FSI_SCHEDULE_RESTART_WITH_ERRORS") = null
#endif
then
fsi.EventLoopScheduleRestart()
else
reraise ())
diagnosticsLogger.AbortOnError(fsiConsoleOutput))

member _.PartialAssemblySignatureUpdated =
fsiInteractionProcessor.PartialAssemblySignatureUpdated
Expand Down
44 changes: 0 additions & 44 deletions src/Compiler/Utilities/lib.fs
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Expand Up @@ -6,9 +6,7 @@ open System
open System.Collections.Generic
open System.IO
open System.Text
open System.Threading
open System.Threading.Tasks
open System.Runtime.InteropServices
open Internal.Utilities.Collections
open Internal.Utilities.Library

Expand Down Expand Up @@ -381,48 +379,6 @@ type Dumper(x:obj) =
[<DebuggerBrowsable(DebuggerBrowsableState.Collapsed)>]
member self.Dump = sprintf "%A" x
#endif
//---------------------------------------------------------------------------
// EnableHeapTerminationOnCorruption()
//---------------------------------------------------------------------------

// USAGE: call UnmanagedProcessExecutionOptions.EnableHeapTerminationOnCorruption() from "main()".
// Note: This is not SDL required but recommended.
module UnmanagedProcessExecutionOptions =

[<DllImport("kernel32.dll")>]
extern UIntPtr private GetProcessHeap()

[<DllImport("kernel32.dll")>]
extern bool private HeapSetInformation(
UIntPtr _HeapHandle,
UInt32 _HeapInformationClass,
UIntPtr _HeapInformation,
UIntPtr _HeapInformationLength)

[<DllImport("kernel32.dll")>]
extern UInt32 private GetLastError()

// Translation of C# from http://swikb/v1/DisplayOnlineDoc.aspx?entryID=826 and copy in bug://5018
[<System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Assert, UnmanagedCode = true)>]
let EnableHeapTerminationOnCorruption() =
if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && Environment.OSVersion.Version.Major >= 6 && // If OS is Vista or higher
Environment.Version.Major < 3) then // and CLR not 3.0 or higher
// "The flag HeapSetInformation sets is available in Windows XP SP3 and later.
// The data structure used for heap information is available on earlier versions of Windows.
// The call will either return TRUE (found and set the flag) or false (flag not found).
// Not a problem in native code, so the program will merrily continue running.
// In managed code, the call to HeapSetInformation is a p/invoke.
// If HeapSetInformation returns FALSE then an exception will be thrown.
// If we are not running an OS which supports this (XP SP3, Vista, Server 2008, and Win7)
// then the call should not be made." -- see bug://5018.
// See also:
// http://blogs.msdn.com/michael_howard/archive/2008/02/18/faq-about-heapsetinformation-in-windows-vista-and-heap-based-buffer-overruns.aspx
let HeapEnableTerminationOnCorruption = 1u : uint32
if not (HeapSetInformation(GetProcessHeap(), HeapEnableTerminationOnCorruption, UIntPtr.Zero, UIntPtr.Zero)) then
raise (System.Security.SecurityException(
"Unable to enable unmanaged process execution option TerminationOnCorruption. " +
"HeapSetInformation() returned FALSE; LastError = 0x" +
GetLastError().ToString("X").PadLeft(8, '0') + "."))

[<RequireQualifiedAccess>]
type MaybeLazy<'T> =
Expand Down
3 changes: 0 additions & 3 deletions src/Compiler/Utilities/lib.fsi
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Expand Up @@ -247,9 +247,6 @@ val inline cacheOptRef: cache: 'a option ref -> f: (unit -> 'a) -> 'a

val inline tryGetCacheValue: cache: cache<'a> -> NonNullSlot<'a> voption

module UnmanagedProcessExecutionOptions =
val EnableHeapTerminationOnCorruption: unit -> unit

[<RequireQualifiedAccess>]
type MaybeLazy<'T> =
| Strict of 'T
Expand Down
5 changes: 0 additions & 5 deletions src/fsc/fscmain.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,10 @@ module internal FSharp.Compiler.CommandLineMain

open System
open System.Reflection
open System.Runtime
open System.Runtime.CompilerServices
open System.Threading

open Internal.Utilities.Library
open Internal.Utilities.Library.Extras
open FSharp.Compiler.AbstractIL
open FSharp.Compiler.AbstractIL.ILBinaryReader
open FSharp.Compiler.CompilerConfig
Expand Down Expand Up @@ -39,9 +37,6 @@ let main (argv) =
// Set the initial phase to garbage collector to batch mode, which improves overall performance.
use _ = UseBuildPhase BuildPhase.Parameter

// An SDL recommendation
UnmanagedProcessExecutionOptions.EnableHeapTerminationOnCorruption()

try

// We are on a compilation thread
Expand Down

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