Skip to content

IL: map the short-lived metadata-only PE reader #20489

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
auduchinok wants to merge 3 commits into
base: main
Choose a base branch
from
+6 −8
Open

IL: map the short-lived metadata-only PE reader #20489

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
82f35db
IL: map the short-lived metadata-only PE reader
auduchinok Aug 24, 2026
94ee863
IO: dispose MemoryMappedStream through Stream.Dispose(bool)
auduchinok Sep 8, 2026
57c504f
Release notes
auduchinok Sep 9, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions docs/release-notes/.FSharp.Compiler.Service/11.0.100.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -169,6 +169,7 @@
* Checker: recover on checking language version ([PR ##19970](https://github.com/dotnet/fsharp/pull/19970))
* Implied argument names for function-to-delegate coercions now fall back to the delegate's `Invoke` parameter names when the function has no recoverable names (e.g. a partial application like `System.Func<int, int>((+) 1)`), instead of synthetic `delegateArg0`, `delegateArg1`, … names. ([PR #20001](https://github.com/dotnet/fsharp/pull/20001))
* Add internal `ResetCompilerGeneratedNameState` to `CompilerGlobalState` name generators so warm-checker re-compilation can produce fresh-process-identical generated names. ([PR #20017](https://github.com/dotnet/fsharp/pull/20017))
* IL: map the short-lived metadata-only PE reader ([PR #20489](https://github.com/dotnet/fsharp/pull/20489))
* Add internal ECMA-335 Edit-and-Continue metadata delta writer to AbstractIL. ([PR #20019](https://github.com/dotnet/fsharp/pull/20019))
* Add Roslyn-format EnC CustomDebugInformation codec and portable PDB method CDI emission support to AbstractIL. ([PR #20018](https://github.com/dotnet/fsharp/pull/20018))
* Extension members (including operators) now participate in SRTP (statically-resolved type parameter) constraint resolution, so member constraints on `inline` code can be satisfied by extension members — including operators defined on types you don't own via type extensions. Intrinsic members keep priority over extension members, and extension members solve SRTP constraints without satisfying nominal static-abstract interface (IWSAM) constraints. Also adds the `[<AllowOverloadOnReturnType>]` attribute for overloads that differ only by return type, and tuple type extensions (`type ('T1 * 'T2) with` / `type struct ('T1 * 'T2) with`). Requires `--langversion:preview`. ([RFC FS-1043](https://github.com/fsharp/fslang-design/blob/main/RFCs/FS-1043-extension-members-for-operators-and-srtp-constraints.md), [fslang-suggestions#230](https://github.com/fsharp/fslang-suggestions/issues/230), [PR #19602](https://github.com/dotnet/fsharp/pull/19602))
Expand Down
2 changes: 1 addition & 1 deletion src/Compiler/AbstractIL/ilread.fs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5168,7 +5168,7 @@ let OpenILModuleReader fileName opts =

// For metadata-only, always use a temporary, short-lived PE file reader, preferably over a memory mapped file.
// Then use the metadata blob as the long-lived memory resource.
let disposer, pefileEager = getBinaryFile fullPath false
let disposer, pefileEager = getBinaryFile fullPath true

@T-Gro T-Gro Sep 9, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

🤖🕵️ [P2] Empty references leave a read handle open until GC, blocking an exclusive reopen after FCS reports the invalid assembly. CreateFromFile throws before disposer exists; the mapping-construction failure path needs to dispose its opened FileStream.

open System
open System.IO
open FSharp.Compiler.CodeAnalysis
open FSharp.Compiler.Text

let dll = Path.GetFullPath "empty.dll"
let script = Path.GetFullPath "check.fsx"
File.WriteAllBytes(dll, [||])
let source = SourceText.ofString (sprintf "#r @\"%s\"\nlet value = 1" dll)
let checker = FSharpChecker.Create()
let options, _ =
    checker.GetProjectOptionsFromScript(script, source, useSdkRefs = true)
    |> Async.RunSynchronously

// Keep GC from hiding the leaked handle during this repro.
if GC.TryStartNoGCRegion(256L * 1024L * 1024L) then
    try
        checker.ParseAndCheckFileInProject(script, 0, source, options)
        |> Async.RunSynchronously |> ignore
        use retry = new FileStream(dll, FileMode.Open, FileAccess.ReadWrite, FileShare.None)
        () // Base succeeds; mapped path throws IOException on Windows.
    finally
        GC.EndNoGCRegion()

use _disposer = disposer

let metadataPhysLoc, metadataSize, peinfo, pectxtEager, pevEager =
Expand Down
11 changes: 4 additions & 7 deletions src/Compiler/Utilities/FileSystem.fs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -199,13 +199,10 @@ type internal MemoryMappedStream(mmf: MemoryMappedFile, length: int64) =
override x.Write(buffer, offset, count) = viewStream.Write(buffer, offset, count)
override x.Read(buffer, offset, count) = viewStream.Read(buffer, offset, count)

override x.Finalize() = x.Dispose()

interface IDisposable with
override x.Dispose() =
GC.SuppressFinalize x
mmf.Dispose()
viewStream.Dispose()
override _.Dispose disposing =
base.Dispose disposing
viewStream.Dispose()
mmf.Dispose()

[<Experimental("This FCS API/Type is experimental and subject to change.")>]
type RawByteMemory(addr: nativeptr<byte>, length: int, holder: obj) =
Expand Down
Loading