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Fix superfluous managed address errors for pointer to non-existent type (#80760)
Fix superfluous managed address errors for pointer to non-existent type ## Summary Fixed issue #38378 where declaring a pointer to a non-existent type would report both CS0246 (type not found) and CS8500/CS0208 (managed address warning/error). Now only CS0246 is reported. ## Changes Made - [x] **Binder_Expressions.cs**: Added error type check in `CheckManagedAddr()` to skip the warning only for truly missing types (LookupResultKind.Empty or NotATypeOrNamespace), but still report for other error scenarios like inaccessible types - [x] **Binder_Symbols.cs**: Removed redundant check (now handled in CheckManagedAddr) - [x] **ConstraintsHelper.cs**: Removed redundant check (now handled in CheckManagedAddr) - [x] Added 4 comprehensive test cases in UnsafeTests.cs using raw string literals with C# pointer style (Type* instead of Type *) - [x] Updated 2 existing tests (PointerTypeInDeconstruction, TypeNamedFile_03_CSharp11) to reflect new behavior for error types from parse errors ## Test Results - ✅ All 4 originally failing tests now pass - ✅ All 4 new test cases pass - ✅ All 491 unsafe tests pass ## Fix Pattern Centralized the check in `CheckManagedAddr` with refined logic: skip warning only for types that are truly missing (Empty/NotATypeOrNamespace), but still report for other error scenarios (e.g., Inaccessible types). Uses modern C# pattern matching syntax for clean code. <!-- START COPILOT CODING AGENT SUFFIX --> <details> <summary>Original prompt</summary> > > ---- > > *This section details on the original issue you should resolve* > > <issue_title>Quality of implementation: superfluous errors for pointer to non-existent type</issue_title> > <issue_description>Compile the following program: > > ```cs > class Program > { > static unsafe void Type(Type *type) > { > } > } > ``` > > # Expected > > Program.cs(3,29): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?) [/Users/hugh/Documents/GitHub/repo/repo.csproj] > > A single error that we can't find the type > > # Actual > > Program.cs(3,29): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?) [/Users/hugh/Documents/GitHub/repo/repo.csproj] > Program.cs(3,29): error CS0208: Cannot take the address of, get the size of, or declare a pointer to a managed type ('Type') [/Users/hugh/Documents/GitHub/repo/repo.csproj] > > The second error is pointless in this case as the type doesn't exist. I would suggest not checking if we can take the address, size or declare a pointer to a non-existent type</issue_description> > > ## Comments on the Issue (you are @copilot in this section) > > <comments> > <comment_new><author>@RikkiGibson</author><body> > Currently we refrain from giving the ManagedAddr error (CS0208) for sizeof and stackalloc array creation when the type is an error type. It seems like we don't need to give the error in this case (pointer to an error type) either.</body></comment_new> > </comments> > </details> Fixes #38378 <!-- START COPILOT CODING AGENT TIPS --> --- 💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more [Copilot coding agent tips](https://gh.io/copilot-coding-agent-tips) in the docs. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com> Co-authored-by: Cyrus Najmabadi <cyrus.najmabadi@gmail.com>
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‎src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs‎

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@@ -1560,6 +1560,11 @@ internal void ReportFieldContextualKeywordConflictIfAny(ParameterSyntax syntax,
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/// <returns>true if managed type-related errors were found, otherwise false.</returns>
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internal static bool CheckManagedAddr(CSharpCompilation compilation, TypeSymbol type, Location location, BindingDiagnosticBag diagnostics, bool errorForManaged = false)
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{
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// Skip the check for error types that represent truly missing types (not found),
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// but still report for error types due to other issues (e.g., inaccessibility).
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if (type is ErrorTypeSymbol { ResultKind: LookupResultKind.Empty })
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return false;
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var useSiteInfo = new CompoundUseSiteInfo<AssemblySymbol>(diagnostics, compilation.Assembly);
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var managedKind = type.GetManagedKind(ref useSiteInfo);
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diagnostics.Add(location, useSiteInfo);

‎src/Compilers/CSharp/Portable/Binder/LookupResultKind.cs‎

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@@ -37,7 +37,7 @@ namespace Microsoft.CodeAnalysis.CSharp
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/// </remarks>
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internal enum LookupResultKind : byte
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{
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// Note: order is important! High values take precedences over lower values.
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// Note: order is important! High values take precedence over lower values.
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Empty,
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NotATypeOrNamespace,

‎src/Compilers/CSharp/Test/Semantic/Semantics/DeconstructionTests.cs‎

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@@ -4120,9 +4120,6 @@ public void Deconstruct(out dynamic x, out dynamic y)
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// (9,10): error CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code
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// (var*[] x4, int y4) = c;
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Diagnostic(ErrorCode.ERR_TypeVarNotFound, "var").WithLocation(9, 10),
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// (9,10): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('var')
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// (var*[] x4, int y4) = c;
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Diagnostic(ErrorCode.WRN_ManagedAddr, "var*").WithArguments("var").WithLocation(9, 10),
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// (9,21): error CS0266: Cannot implicitly convert type 'dynamic' to 'int'. An explicit conversion exists (are you missing a cast?)
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// (var*[] x4, int y4) = c;
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Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "int y4").WithArguments("dynamic", "int").WithLocation(9, 21)

‎src/Compilers/CSharp/Test/Semantic/Semantics/UnsafeTests.cs‎

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@@ -14299,6 +14299,125 @@ class PointerImpl : IPointerTest
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);
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}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
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public void PointerToNonExistentType_NoSuperfluousError()
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{
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var source = """
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class Program
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{
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static unsafe void Method(Type* type)
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{
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}
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}
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""";
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CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (3,31): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?)
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// static unsafe void Method(Type* type)
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Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type").WithArguments("Type").WithLocation(3, 31));
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}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
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public void PointerToInaccessibleType()
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{
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var source = """
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class X { class Y { } }
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class Program
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{
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static unsafe void Method(X.Y* y)
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{
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}
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}
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""";
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CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (5,33): error CS0122: 'X.Y' is inaccessible due to its protection level
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// static unsafe void Method(X.Y* y)
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Diagnostic(ErrorCode.ERR_BadAccess, "Y").WithArguments("X.Y").WithLocation(5, 33),
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// (5,36): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('X.Y')
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// static unsafe void Method(X.Y* y)
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Diagnostic(ErrorCode.WRN_ManagedAddr, "y").WithArguments("X.Y").WithLocation(5, 36));
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}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
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public void PointerToWrongArity()
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{
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var source = """
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class X { }
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class Program
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{
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static unsafe void Method(X<int>* y)
14350+
{
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}
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}
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""";
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CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (5,31): error CS0308: The non-generic type 'X' cannot be used with type arguments
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// static unsafe void Method(X<int>* y)
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Diagnostic(ErrorCode.ERR_HasNoTypeVars, "X<int>").WithArguments("X", "type").WithLocation(5, 31),
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// (5,39): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('X<int>')
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// static unsafe void Method(X<int>* y)
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Diagnostic(ErrorCode.WRN_ManagedAddr, "y").WithArguments("X<int>").WithLocation(5, 39));
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}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
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public void PointerToNonExistentType_MultiplePointers()
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{
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var source = """
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class Program
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{
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static unsafe void Method(Type1* p1, Type2** p2)
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{
14371+
}
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}
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""";
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CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (3,31): error CS0246: The type or namespace name 'Type1' could not be found (are you missing a using directive or an assembly reference?)
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// static unsafe void Method(Type1* p1, Type2** p2)
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Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type1").WithArguments("Type1").WithLocation(3, 31),
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// (3,42): error CS0246: The type or namespace name 'Type2' could not be found (are you missing a using directive or an assembly reference?)
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// static unsafe void Method(Type1* p1, Type2** p2)
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Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type2").WithArguments("Type2").WithLocation(3, 42));
14381+
}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/36877")]
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public void PointerToNonExistentType_LocalVariable()
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{
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var source = """
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unsafe class Program
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{
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static void Method()
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{
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Type* local;
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}
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}
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""";
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CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (5,9): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?)
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// Type* local;
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Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type").WithArguments("Type").WithLocation(5, 9),
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// (5,15): warning CS0168: The variable 'local' is declared but never used
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// Type* local;
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Diagnostic(ErrorCode.WRN_UnreferencedVar, "local").WithArguments("local").WithLocation(5, 15));
14402+
}
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
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public void PointerToExistingManagedType_StillReportsError()
14406+
{
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var source = """
14408+
unsafe class Program
14409+
{
14410+
static void Method(string* str)
14411+
{
14412+
}
14413+
}
14414+
""";
14415+
CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
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// (3,32): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
14417+
// static void Method(string* str)
14418+
Diagnostic(ErrorCode.WRN_ManagedAddr, "str").WithArguments("string").WithLocation(3, 32));
14419+
}
14420+
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[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/44088")]
1430314422
public void PointerTypeInTypeParameter_Field_RequiresUnsafeContext()
1430414423
{

‎src/Compilers/CSharp/Test/Syntax/Parsing/FileModifierParsingTests.cs‎

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Original file line numberDiff line numberDiff line change
@@ -1816,9 +1816,6 @@ public unsafe class C
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// (7,18): error CS0106: The modifier 'file' is not valid for this item
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// public file* _ptr;
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Diagnostic(ErrorCode.ERR_BadMemberFlag, "_ptr").WithArguments("file").WithLocation(7, 18),
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// (7,18): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('?')
1820-
// public file* _ptr;
1821-
Diagnostic(ErrorCode.WRN_ManagedAddr, "_ptr").WithArguments("?").WithLocation(7, 18),
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// (8,16): error CS1031: Type expected
18231820
// public file? _nullable;
18241821
Diagnostic(ErrorCode.ERR_TypeExpected, "?").WithLocation(8, 16),

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