From 9ab4e3935837eb68a0681b10c75cfc641e001ed0 Mon Sep 17 00:00:00 2001
From: Jakub Majocha <1760221+majocha@users.noreply.github.com>
Date: Mon, 9 Dec 2024 12:25:31 +0100
Subject: [PATCH] Make sure CheckAndThrow is invoked only within ambient
 Cancellable context (#18037)

* make sure CheckAndThrow is invoked in ambient Cancellable context

* wip

* ilverify

* disable assert by env var

* f

* rn

* ilverify

---------

Co-authored-by: Petr <psfinaki@users.noreply.github.com>
---
 .../.FSharp.Compiler.Service/9.0.200.md       |  2 ++
 src/Compiler/Utilities/Cancellable.fs         | 21 ++++++++++++-------
 src/Compiler/Utilities/Cancellable.fsi        |  1 +
 .../ModuleReaderCancellationTests.fs          |  6 ++++++
 ...y_FSharp.Compiler.Service_Debug_net9.0.bsl | 12 +++++------
 ....Compiler.Service_Debug_netstandard2.0.bsl | 12 +++++------
 6 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/docs/release-notes/.FSharp.Compiler.Service/9.0.200.md b/docs/release-notes/.FSharp.Compiler.Service/9.0.200.md
index 66889c7ce39..7c7f9652b19 100644
--- a/docs/release-notes/.FSharp.Compiler.Service/9.0.200.md
+++ b/docs/release-notes/.FSharp.Compiler.Service/9.0.200.md
@@ -40,5 +40,7 @@
 * Warn on uppercase identifiers in patterns. ([PR #15816](https://github.com/dotnet/fsharp/pull/15816))
 * Better ranges for `inherit` objects error reporting. ([PR #17893](https://github.com/dotnet/fsharp/pull/17893))
 * Better ranges for #nowarn error reporting; bring back #nowarn warnings for --langVersion:80; add warnings under feature flag ([PR #17871](https://github.com/dotnet/fsharp/pull/17871))
+* Better ranges for #nowarn error reporting; bring back #nowarn warnings for --langVersion:80; add warnings under feature flag ([PR #17871](https://github.com/dotnet/fsharp/pull/17871))
+* CheckAndThrow can be invoked only from within Cancellable context ([PR #18037](https://github.com/dotnet/fsharp/pull/18037))
 
 ### Breaking Changes
diff --git a/src/Compiler/Utilities/Cancellable.fs b/src/Compiler/Utilities/Cancellable.fs
index c173e29779f..b3531c74890 100644
--- a/src/Compiler/Utilities/Cancellable.fs
+++ b/src/Compiler/Utilities/Cancellable.fs
@@ -2,24 +2,31 @@ namespace FSharp.Compiler
 
 open System
 open System.Threading
-open Internal.Utilities.Library
 
 [<Sealed>]
 type Cancellable =
-    static let token = AsyncLocal<CancellationToken>()
+    static let tokenHolder = AsyncLocal<CancellationToken voption>()
 
-    static member Token = token.Value
+    static let guard =
+        String.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable("DISABLE_CHECKANDTHROW_ASSERT"))
+
+    static let ensureToken msg =
+        tokenHolder.Value
+        |> ValueOption.defaultWith (fun () -> if guard then failwith msg else CancellationToken.None)
+
+    static member Token = ensureToken "Token not available outside of Cancellable computation."
 
     static member UsingToken(ct) =
-        let oldCt = token.Value
-        token.Value <- ct
+        let oldCt = tokenHolder.Value
+        tokenHolder.Value <- ValueSome ct
 
         { new IDisposable with
-            member this.Dispose() = token.Value <- oldCt
+            member _.Dispose() = tokenHolder.Value <- oldCt
         }
 
     static member CheckAndThrow() =
-        token.Value.ThrowIfCancellationRequested()
+        let token = ensureToken "CheckAndThrow invoked outside of Cancellable computation."
+        token.ThrowIfCancellationRequested()
 
 namespace Internal.Utilities.Library
 
diff --git a/src/Compiler/Utilities/Cancellable.fsi b/src/Compiler/Utilities/Cancellable.fsi
index 23515432bdd..32d1d6e0a04 100644
--- a/src/Compiler/Utilities/Cancellable.fsi
+++ b/src/Compiler/Utilities/Cancellable.fsi
@@ -5,6 +5,7 @@ open System.Threading
 
 [<Sealed>]
 type Cancellable =
+    /// For use in testing only. Cancellable.token should be set only by the cancellable computation.
     static member internal UsingToken: CancellationToken -> IDisposable
     static member Token: CancellationToken
     static member CheckAndThrow: unit -> unit
diff --git a/tests/FSharp.Compiler.Service.Tests/ModuleReaderCancellationTests.fs b/tests/FSharp.Compiler.Service.Tests/ModuleReaderCancellationTests.fs
index c760a5f070c..a61f61f84f8 100644
--- a/tests/FSharp.Compiler.Service.Tests/ModuleReaderCancellationTests.fs
+++ b/tests/FSharp.Compiler.Service.Tests/ModuleReaderCancellationTests.fs
@@ -20,6 +20,7 @@ let mutable private wasCancelled = false
 let runCancelFirstTime f =
     let mutable requestCount = 0
     fun () ->
+        use _ = Cancellable.UsingToken cts.Token
         if requestCount = 0 then
             cts.Cancel()
 
@@ -147,6 +148,7 @@ let referenceReaderProject getPreTypeDefs (cancelOnModuleAccess: bool) (options:
 let parseAndCheck path source options =
     cts <- new CancellationTokenSource()
     wasCancelled <- false
+    use _ = Cancellable.UsingToken cts.Token
 
     try
         match Async.RunSynchronously(checker.ParseAndCheckFileInProject(path, 0, SourceText.ofString source, options), cancellationToken = cts.Token) with
@@ -173,6 +175,10 @@ let t: T = T()
 """
 
 
+[<Fact>]
+let ``CheckAndThrow is not allowed to throw outside of cancellable`` () =
+    Assert.Throws<Exception>(fun () -> Cancellable.CheckAndThrow())
+
 [<Fact>]
 let ``Type defs 01 - assembly import`` () =
     let source = source1
diff --git a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_net9.0.bsl b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_net9.0.bsl
index 31c4fa6c2ca..c527d99ccf5 100644
--- a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_net9.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_net9.0.bsl
@@ -21,14 +21,14 @@
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CodeAnalysis.Hosted.CompilerHelpers::fscCompile([FSharp.Compiler.Service]FSharp.Compiler.CodeAnalysis.LegacyReferenceResolver, string, string[])][offset 0x00000082][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CodeAnalysis.Hosted.CompilerHelpers::fscCompile([FSharp.Compiler.Service]FSharp.Compiler.CodeAnalysis.LegacyReferenceResolver, string, string[])][offset 0x0000008B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+MagicAssemblyResolution::ResolveAssemblyCore([FSharp.Compiler.Service]Internal.Utilities.Library.CompilationThreadToken, [FSharp.Compiler.Service]FSharp.Compiler.Text.Range, [FSharp.Compiler.Service]FSharp.Compiler.CompilerConfig+TcConfigBuilder, [FSharp.Compiler.Service]FSharp.Compiler.CompilerImports+TcImports, [FSharp.Compiler.Service]FSharp.Compiler.Interactive.Shell+FsiDynamicCompiler, [FSharp.Compiler.Service]FSharp.Compiler.Interactive.Shell+FsiConsoleOutput, string)][offset 0x00000015][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+clo@3510-789::Invoke([S.P.CoreLib]System.Tuple`3<char[],int32,int32>)][offset 0x000001E5][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+clo@3510-790::Invoke([S.P.CoreLib]System.Tuple`3<char[],int32,int32>)][offset 0x000001E5][found Char] Unexpected type on the stack.
 [IL]: Error [UnmanagedPointer]: : FSharp.Compiler.Interactive.Shell+Utilities+pointerToNativeInt@110::Invoke(object)][offset 0x00000007] Unmanaged pointers are not a verifiable type.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharpCheckerResults+dataTipOfReferences@2205::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000084][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000032][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000003B][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000082][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000008B][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000094][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000032][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000003B][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000082][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000008B][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000094][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.StaticLinking+TypeForwarding::followTypeForwardForILTypeRef([FSharp.Compiler.Service]FSharp.Compiler.AbstractIL.IL+ILTypeRef)][offset 0x00000010][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CompilerOptions::getCompilerOption([FSharp.Compiler.Service]FSharp.Compiler.CompilerOptions+CompilerOption, [FSharp.Core]Microsoft.FSharp.Core.FSharpOption`1<int32>)][offset 0x000000E6][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CompilerOptions::AddPathMapping([FSharp.Compiler.Service]FSharp.Compiler.CompilerConfig+TcConfigBuilder, string)][offset 0x0000000B][found Char] Unexpected type on the stack.
diff --git a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
index 1e8bbd6fcee..7d4eff968ac 100644
--- a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
@@ -28,18 +28,18 @@
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CodeAnalysis.Hosted.CompilerHelpers::fscCompile([FSharp.Compiler.Service]FSharp.Compiler.CodeAnalysis.LegacyReferenceResolver, string, string[])][offset 0x0000008B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+FsiStdinSyphon::GetLine(string, int32)][offset 0x00000039][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+MagicAssemblyResolution::ResolveAssemblyCore([FSharp.Compiler.Service]Internal.Utilities.Library.CompilationThreadToken, [FSharp.Compiler.Service]FSharp.Compiler.Text.Range, [FSharp.Compiler.Service]FSharp.Compiler.CompilerConfig+TcConfigBuilder, [FSharp.Compiler.Service]FSharp.Compiler.CompilerImports+TcImports, [FSharp.Compiler.Service]FSharp.Compiler.Interactive.Shell+FsiDynamicCompiler, [FSharp.Compiler.Service]FSharp.Compiler.Interactive.Shell+FsiConsoleOutput, string)][offset 0x00000015][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+clo@3510-789::Invoke([S.P.CoreLib]System.Tuple`3<char[],int32,int32>)][offset 0x000001E5][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+clo@3510-790::Invoke([S.P.CoreLib]System.Tuple`3<char[],int32,int32>)][offset 0x000001E5][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Interactive.Shell+FsiInteractionProcessor::CompletionsForPartialLID([FSharp.Compiler.Service]FSharp.Compiler.Interactive.Shell+FsiDynamicCompilerState, string)][offset 0x0000001B][found Char] Unexpected type on the stack.
 [IL]: Error [UnmanagedPointer]: : FSharp.Compiler.Interactive.Shell+Utilities+pointerToNativeInt@110::Invoke(object)][offset 0x00000007] Unmanaged pointers are not a verifiable type.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharpCheckerResults+dataTipOfReferences@2205::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000084][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.EditorServices.AssemblyContent+traverseMemberFunctionAndValues@176::Invoke([FSharp.Compiler.Service]FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue)][offset 0x00000059][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.EditorServices.AssemblyContent+traverseEntity@218::GenerateNext([S.P.CoreLib]System.Collections.Generic.IEnumerable`1<FSharp.Compiler.EditorServices.AssemblySymbol>&)][offset 0x000000DA][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.EditorServices.ParsedInput+visitor@1423-6::VisitExpr([FSharp.Core]Microsoft.FSharp.Collections.FSharpList`1<FSharp.Compiler.Syntax.SyntaxNode>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<FSharp.Compiler.Syntax.SynExpr,Microsoft.FSharp.Core.FSharpOption`1<FSharp.Compiler.EditorServices.CompletionContext>>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<FSharp.Compiler.Syntax.SynExpr,Microsoft.FSharp.Core.FSharpOption`1<FSharp.Compiler.EditorServices.CompletionContext>>, [FSharp.Compiler.Service]FSharp.Compiler.Syntax.SynExpr)][offset 0x00000605][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000032][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000003B][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000082][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000008B][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-501::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000094][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000032][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000003B][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000082][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000008B][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-502::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000094][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Symbols+fullName@2490-1::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000015][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CreateILModule+MainModuleBuilder::ConvertProductVersionToILVersionInfo(string)][offset 0x00000011][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.StaticLinking+TypeForwarding::followTypeForwardForILTypeRef([FSharp.Compiler.Service]FSharp.Compiler.AbstractIL.IL+ILTypeRef)][offset 0x00000010][found Char] Unexpected type on the stack.