Nested local functions causes KeyNotFoundException

[Keboo]

Version Used:
Microsoft Visual Studio Enterprise 2017
Version 15.3.1
VisualStudio.15.Release/15.3.1+26730.8
Microsoft .NET Framework
Version 4.7.02046

Steps to Reproduce:

1. Create a new C# project
2. Add the following code

public class Class1
{
    private void Test()
    {
        bool outside = true;

        void Inner() //This can also be a lambda (ie. Action action = () => { ... };)
        {
            void Bar()
            {
            }

            void Foo()
            {
                Bar();

                bool captured = outside;
            }
        }
    }
}

3. Compile with VS 2017 15.3.1

Example repository available here.
This same code does compile with VS 2017 v15.2 (26430.15 release).

Expected Behavior:
Compile succeeds without error.

Actual Behavior:
CSC.exe crash with error code -2146232797

MSBuild output:

1>  Task "Csc"
1>    C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\Bin\Roslyn\csc.exe /noconfig /unsafe- /checked- /nowarn:1701,1702,1705,1701,1702,2008 /nostdlib+ /errorreport:prompt /warn:4 /define:TRACE;DEBUG;NETSTANDARD1_4 /errorendlocation /preferreduilang:en-US /reference:C:\Users\Kevin\.nuget\packages\microsoft.win32.primitives\4.3.0\ref\netstandard1.3\Microsoft.Win32.Primitives.dll /reference:C:\Users\Kevin\.nuget\packages\system.appcontext\4.3.0\ref\netstandard1.3\System.AppContext.dll /reference:C:\Users\Kevin\.nuget\packages\system.collections.concurrent\4.3.0\ref\netstandard1.3\System.Collections.Concurrent.dll /reference:C:\Users\Kevin\.nuget\packages\system.collections\4.3.0\ref\netstandard1.3\System.Collections.dll /reference:C:\Users\Kevin\.nuget\packages\system.console\4.3.0\ref\netstandard1.3\System.Console.dll /reference:C:\Users\Kevin\.nuget\packages\system.diagnostics.debug\4.3.0\ref\netstandard1.3\System.Diagnostics.Debug.dll /reference:C:\Users\Kevin\.nuget\packages\system.diagnostics.tools\4.3.0\ref\netstandard1.0\System.Diagnostics.Tools.dll /reference:C:\Users\Kevin\.nuget\packages\system.diagnostics.tracing\4.3.0\ref\netstandard1.3\System.Diagnostics.Tracing.dll /reference:C:\Users\Kevin\.nuget\packages\system.globalization.calendars\4.3.0\ref\netstandard1.3\System.Globalization.Calendars.dll /reference:C:\Users\Kevin\.nuget\packages\system.globalization\4.3.0\ref\netstandard1.3\System.Globalization.dll /reference:C:\Users\Kevin\.nuget\packages\system.io.compression\4.3.0\ref\netstandard1.3\System.IO.Compression.dll /reference:C:\Users\Kevin\.nuget\packages\system.io.compression.zipfile\4.3.0\ref\netstandard1.3\System.IO.Compression.ZipFile.dll /reference:C:\Users\Kevin\.nuget\packages\system.io\4.3.0\ref\netstandard1.3\System.IO.dll /reference:C:\Users\Kevin\.nuget\packages\system.io.filesystem\4.3.0\ref\netstandard1.3\System.IO.FileSystem.dll /reference:C:\Users\Kevin\.nuget\packages\system.io.filesystem.primitives\4.3.0\ref\netstandard1.3\System.IO.FileSystem.Primitives.dll /reference:C:\Users\Kevin\.nuget\packages\system.linq\4.3.0\ref\netstandard1.0\System.Linq.dll /reference:C:\Users\Kevin\.nuget\packages\system.linq.expressions\4.3.0\ref\netstandard1.3\System.Linq.Expressions.dll /reference:C:\Users\Kevin\.nuget\packages\system.net.http\4.3.0\ref\netstandard1.3\System.Net.Http.dll /reference:C:\Users\Kevin\.nuget\packages\system.net.primitives\4.3.0\ref\netstandard1.3\System.Net.Primitives.dll /reference:C:\Users\Kevin\.nuget\packages\system.net.sockets\4.3.0\ref\netstandard1.3\System.Net.Sockets.dll /reference:C:\Users\Kevin\.nuget\packages\system.objectmodel\4.3.0\ref\netstandard1.3\System.ObjectModel.dll /reference:C:\Users\Kevin\.nuget\packages\system.reflection\4.3.0\ref\netstandard1.3\System.Reflection.dll /reference:C:\Users\Kevin\.nuget\packages\system.reflection.extensions\4.3.0\ref\netstandard1.0\System.Reflection.Extensions.dll /reference:C:\Users\Kevin\.nuget\packages\system.reflection.primitives\4.3.0\ref\netstandard1.0\System.Reflection.Primitives.dll /reference:C:\Users\Kevin\.nuget\packages\system.resources.resourcemanager\4.3.0\ref\netstandard1.0\System.Resources.ResourceManager.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime\4.3.0\ref\netstandard1.3\System.Runtime.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime.extensions\4.3.0\ref\netstandard1.3\System.Runtime.Extensions.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime.handles\4.3.0\ref\netstandard1.3\System.Runtime.Handles.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime.interopservices\4.3.0\ref\netstandard1.3\System.Runtime.InteropServices.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime.interopservices.runtimeinformation\4.3.0\ref\netstandard1.1\System.Runtime.InteropServices.RuntimeInformation.dll /reference:C:\Users\Kevin\.nuget\packages\system.runtime.numerics\4.3.0\ref\netstandard1.1\System.Runtime.Numerics.dll /reference:C:\Users\Kevin\.nuget\packages\system.security.cryptography.algorithms\4.3.0\ref\netstandard1.4\System.Security.Cryptography.Algorithms.dll /reference:C:\Users\Kevin\.nuget\packages\system.security.cryptography.encoding\4.3.0\ref\netstandard1.3\System.Security.Cryptography.Encoding.dll /reference:C:\Users\Kevin\.nuget\packages\system.security.cryptography.primitives\4.3.0\ref\netstandard1.3\System.Security.Cryptography.Primitives.dll /reference:C:\Users\Kevin\.nuget\packages\system.security.cryptography.x509certificates\4.3.0\ref\netstandard1.4\System.Security.Cryptography.X509Certificates.dll /reference:C:\Users\Kevin\.nuget\packages\system.text.encoding\4.3.0\ref\netstandard1.3\System.Text.Encoding.dll /reference:C:\Users\Kevin\.nuget\packages\system.text.encoding.extensions\4.3.0\ref\netstandard1.3\System.Text.Encoding.Extensions.dll /reference:C:\Users\Kevin\.nuget\packages\system.text.regularexpressions\4.3.0\ref\netstandard1.3\System.Text.RegularExpressions.dll /reference:C:\Users\Kevin\.nuget\packages\system.threading\4.3.0\ref\netstandard1.3\System.Threading.dll /reference:C:\Users\Kevin\.nuget\packages\system.threading.tasks\4.3.0\ref\netstandard1.3\System.Threading.Tasks.dll /reference:C:\Users\Kevin\.nuget\packages\system.threading.timer\4.3.0\ref\netstandard1.2\System.Threading.Timer.dll /reference:C:\Users\Kevin\.nuget\packages\system.xml.readerwriter\4.3.0\ref\netstandard1.3\System.Xml.ReaderWriter.dll /reference:C:\Users\Kevin\.nuget\packages\system.xml.xdocument\4.3.0\ref\netstandard1.3\System.Xml.XDocument.dll /debug+ /debug:portable /filealign:512 /nologo /optimize- /out:obj\Debug\netstandard1.4\NestedInnerFunctionsBug.dll /ruleset:"C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Team Tools\Static Analysis Tools\\Rule Sets\MinimumRecommendedRules.ruleset" /target:library /warnaserror- /utf8output /deterministic+ Class1.cs "C:\Users\Kevin\AppData\Local\Temp\.NETStandard,Version=v1.4.AssemblyAttributes.cs" obj\Debug\netstandard1.4\\TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs obj\Debug\netstandard1.4\\TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs obj\Debug\netstandard1.4\\TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs obj\Debug\netstandard1.4\NestedInnerFunctionsBug.AssemblyInfo.cs
1>    Using shared compilation with compiler from directory: C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\Bin\Roslyn
1>    C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\Bin\Roslyn\Microsoft.CSharp.Core.targets(84,5): error MSB6006: "csc.exe" exited with code -2146232797.
1>  Done executing task "Csc" -- FAILED.

Event view log:

Application: csc.exe
Framework Version: v4.0.30319
Description: The application requested process termination through System.Environment.FailFast(string message).
Message: System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   at System.ThrowHelper.ThrowKeyNotFoundException()
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteLambdaOrLocalFunction(IBoundLambdaOrFunction node, ClosureKind& closureKind, NamedTypeSymbol& translatedLambdaContainer, LambdaFrame& containerAsFrame, BoundNode& lambdaScope, DebugId& topLevelMethodId, DebugId& lambdaId)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitLocalFunctionStatement(BoundLocalFunctionStatement node)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(BoundNode node)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteBlock(BoundBlock node, ArrayBuilder`1 prologue, ArrayBuilder`1 newLocals)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitBlock(BoundBlock node)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteLambdaOrLocalFunction(IBoundLambdaOrFunction node, ClosureKind& closureKind, NamedTypeSymbol& translatedLambdaContainer, LambdaFrame& containerAsFrame, BoundNode& lambdaScope, DebugId& topLevelMethodId, DebugId& lambdaId)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitLocalFunctionStatement(BoundLocalFunctionStatement node)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(BoundNode node)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteBlock(BoundBlock node, ArrayBuilder`1 prologue, ArrayBuilder`1 newLocals)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.IntroduceFrame(BoundNode node, LambdaFrame frame, Func`3 F)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitBlock(BoundBlock node)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(BoundNode node)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.Rewrite(BoundStatement loweredBody, NamedTypeSymbol thisType, ParameterSymbol thisParameter, MethodSymbol method, Int32 methodOrdinal, MethodSymbol substitutedSourceMethod, ArrayBuilder`1 lambdaDebugInfoBuilder, ArrayBuilder`1 closureDebugInfoBuilder, VariableSlotAllocator slotAllocatorOpt, TypeCompilationState compilationState, DiagnosticBag diagnostics, HashSet`1 assignLocals)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.LowerBodyOrInitializer(MethodSymbol method, Int32 methodOrdinal, BoundStatement body, SynthesizedSubmissionFields previousSubmissionFields, TypeCompilationState compilationState, Boolean instrumentForDynamicAnalysis, DebugDocumentProvider debugDocumentProvider, ImmutableArray`1& dynamicAnalysisSpans, DiagnosticBag diagnostics, VariableSlotAllocator& lazyVariableSlotAllocator, ArrayBuilder`1 lambdaDebugInfoBuilder, ArrayBuilder`1 closureDebugInfoBuilder, StateMachineTypeSymbol& stateMachineTypeOpt)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileMethod(MethodSymbol methodSymbol, Int32 methodOrdinal, ProcessedFieldInitializers& processedInitializers, SynthesizedSubmissionFields previousSubmissionFields, TypeCompilationState compilationState)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileNamedType(NamedTypeSymbol containingType)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.<>c__DisplayClass21_0.<CompileNamedTypeAsTask>b__0()
Stack:
   at System.Environment.FailFast(System.String, System.Exception)
   at Microsoft.CodeAnalysis.FatalError.Report(System.Exception, System.Action`1<System.Exception>)
   at Microsoft.CodeAnalysis.FatalError.ReportUnlessCanceled(System.Exception)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler+<>c__DisplayClass21_0.<CompileNamedTypeAsTask>b__0()
   at System.ThrowHelper.ThrowKeyNotFoundException()
   at System.Collections.Generic.Dictionary`2[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].get_Item(System.__Canon)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteLambdaOrLocalFunction(Microsoft.CodeAnalysis.CSharp.IBoundLambdaOrFunction, Microsoft.CodeAnalysis.CSharp.ClosureKind ByRef, Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol ByRef, Microsoft.CodeAnalysis.CSharp.LambdaFrame ByRef, Microsoft.CodeAnalysis.CSharp.BoundNode ByRef, Microsoft.CodeAnalysis.CodeGen.DebugId ByRef, Microsoft.CodeAnalysis.CodeGen.DebugId ByRef)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitLocalFunctionStatement(Microsoft.CodeAnalysis.CSharp.BoundLocalFunctionStatement)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(Microsoft.CodeAnalysis.CSharp.BoundNode)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteBlock(Microsoft.CodeAnalysis.CSharp.BoundBlock, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.BoundExpression>, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol>)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitBlock(Microsoft.CodeAnalysis.CSharp.BoundBlock)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteLambdaOrLocalFunction(Microsoft.CodeAnalysis.CSharp.IBoundLambdaOrFunction, Microsoft.CodeAnalysis.CSharp.ClosureKind ByRef, Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol ByRef, Microsoft.CodeAnalysis.CSharp.LambdaFrame ByRef, Microsoft.CodeAnalysis.CSharp.BoundNode ByRef, Microsoft.CodeAnalysis.CodeGen.DebugId ByRef, Microsoft.CodeAnalysis.CodeGen.DebugId ByRef)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitLocalFunctionStatement(Microsoft.CodeAnalysis.CSharp.BoundLocalFunctionStatement)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(Microsoft.CodeAnalysis.CSharp.BoundNode)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.RewriteBlock(Microsoft.CodeAnalysis.CSharp.BoundBlock, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.BoundExpression>, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol>)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.IntroduceFrame(Microsoft.CodeAnalysis.CSharp.BoundNode, Microsoft.CodeAnalysis.CSharp.LambdaFrame, System.Func`3<Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.BoundExpression>,Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol>,Microsoft.CodeAnalysis.CSharp.BoundNode>)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.VisitBlock(Microsoft.CodeAnalysis.CSharp.BoundBlock)
   at Microsoft.CodeAnalysis.CSharp.BoundTreeRewriterWithStackGuard.Visit(Microsoft.CodeAnalysis.CSharp.BoundNode)
   at Microsoft.CodeAnalysis.CSharp.LambdaRewriter.Rewrite(Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Int32, Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CodeGen.LambdaDebugInfo>, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CodeGen.ClosureDebugInfo>, Microsoft.CodeAnalysis.CodeGen.VariableSlotAllocator, Microsoft.CodeAnalysis.CSharp.TypeCompilationState, Microsoft.CodeAnalysis.DiagnosticBag, System.Collections.Generic.HashSet`1<Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol>)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.LowerBodyOrInitializer(Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Int32, Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp.SynthesizedSubmissionFields, Microsoft.CodeAnalysis.CSharp.TypeCompilationState, Boolean, Microsoft.CodeAnalysis.CodeGen.DebugDocumentProvider, System.Collections.Immutable.ImmutableArray`1<Microsoft.CodeAnalysis.CodeGen.SourceSpan> ByRef, Microsoft.CodeAnalysis.DiagnosticBag, Microsoft.CodeAnalysis.CodeGen.VariableSlotAllocator ByRef, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CodeGen.LambdaDebugInfo>, Microsoft.CodeAnalysis.ArrayBuilder`1<Microsoft.CodeAnalysis.CodeGen.ClosureDebugInfo>, Microsoft.CodeAnalysis.CSharp.StateMachineTypeSymbol ByRef)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileMethod(Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Int32, ProcessedFieldInitializers ByRef, Microsoft.CodeAnalysis.CSharp.SynthesizedSubmissionFields, Microsoft.CodeAnalysis.CSharp.TypeCompilationState)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileNamedType(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol)
   at Microsoft.CodeAnalysis.CSharp.MethodCompiler+<>c__DisplayClass21_0.<CompileNamedTypeAsTask>b__0()
   at Roslyn.Utilities.UICultureUtilities+<>c__DisplayClass5_0.<WithCurrentUICulture>b__0()
   at System.Threading.Tasks.Task.Execute()
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(System.Threading.Tasks.Task ByRef)
   at System.Threading.Tasks.Task.ExecuteEntry(Boolean)
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

Potentially related to #17814 and #16895?

[svick]

This seems to have been already fixed by #21367. That change is not included in 15.3, but should be in a future version.

[jaredpar]

Agree with @svick that this should be fixed already. Will let @agocke verify + add a test case.

[benjamin-hodgson]

I'm getting the same error with a slightly different repro:

class Class
{
    public void Meth()
    {
        var x = 3;
        {
            var y = 4;
            void Local()
            {
                Console.WriteLine(x);
                Func<int> f = () => y;
            }
            Local();
        }
    }
}

The key to the repro (at least in this case) appears to be having a local function inside a local function, each of which accesses a different local from two scopes out.