Report error for native PDB limit

src/Compilers/CSharp/Test/Emit2/PDB/PDBTests.cs

@@ -22,6 +22,7 @@
 using Roslyn.Test.PdbUtilities;
 using Roslyn.Test.Utilities;
 using Roslyn.Test.Utilities.TestGenerators;
+using Roslyn.Utilities;
 using Xunit;
 
 namespace Microsoft.CodeAnalysis.CSharp.UnitTests.PDB
@@ -367,6 +368,83 @@ public void SymWriterErrors4()
  Assert.False(result.Success);
  }
 
+ [ConditionalTheory(typeof(WindowsOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
+ [WorkItem("https://github.com/dotnet/roslyn/issues/75237")]
+ [InlineData(0x9_999)]
+ [InlineData(0x9_000)]
+ public void NativeWriterLimit_Under(int length)
+ {
+ CompileWithMockedCustomMetadata(length).Diagnostics.Verify();
+ }
+
+ [ConditionalTheory(typeof(WindowsOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
+ [WorkItem("https://github.com/dotnet/roslyn/issues/75237")]
+ [InlineData(0x10_000)]
+ [InlineData(0x20_000)]
+ public void NativeWriterLimit_Over(int length)
+ {
+ CompileWithMockedCustomMetadata(length).Diagnostics.Verify(
+ // error CS0041: Unexpected error writing debug information -- 'Insufficient memory to continue the execution of the program.'
+ Diagnostic(ErrorCode.FTL_DebugEmitFailure).WithArguments("Insufficient memory to continue the execution of the program.").WithLocation(1, 1));
+ }
+
+ private static EmitResult CompileWithMockedCustomMetadata(int length)
+ {
+ var comp = CreateCompilation("""
+ class C
+ {
+ void M() { }
+ }
+ """);
+ return comp.Emit(
+ peStream: new MemoryStream(),
+ metadataPEStream: null,
+ pdbStream: new MemoryStream(),
+ xmlDocumentationStream: null,
+ cancellationToken: default,
+ win32Resources: null,
+ manifestResources: null,
+ options: null,
+ debugEntryPoint: null,
+ sourceLinkStream: null,
+ embeddedTexts: null,
+ rebuildData: null,
+ testData: new CompilationTestData
+ {
+ SymWriterFactory = metadataProvider =>
+ {
+ var writer = SymWriterTestUtilities.CreateUnmanagedWriter(metadataProvider);
+ return new CustomMetadataSymUnmanagedWriter(writer, new byte[length]);
+ },
+ });
+ }
+
+ [ConditionalFact(typeof(WindowsOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
+ [WorkItem("https://github.com/dotnet/roslyn/issues/75237")]
+ public void NativeWriterLimit_EndToEnd()
+ {
+ var locals = Enumerable.Range(0, 14_000)
+ .Select(i => $"""
+ var local{i} = {i};
+ M2(local{i});
+ """)
+ .Join(Environment.NewLine);
+ var source = $$"""
+ namespace N;
+ class C
+ {
+ void M1()
+ {
+ {{locals}}
+ }
+ void M2(int x) { }
+ }
+ """;
+ CreateCompilation(source, options: TestOptions.DebugDll).VerifyEmitDiagnostics(
+ // error CS0041: Unexpected error writing debug information -- 'Cannot emit native PDB for method 'N.C.M1()' because its debug metadata size 69096 is over the limit 65536.'
+ Diagnostic(ErrorCode.FTL_DebugEmitFailure).WithArguments(string.Format(CodeAnalysisResources.SymWriterMetadataOverLimit, "N.C.M1()", 69096, 65536)).WithLocation(1, 1));
+ }
+
  [WorkItem(1067635, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1067635")]
  [Fact]
  public void SuppressDynamicAndEncCDIForWinRT()

src/Compilers/Core/Portable/CodeAnalysisResources.resx

@@ -507,6 +507,9 @@
  <data name="SymWriterDoesNotSupportSourceLink" xml:space="preserve">
  <value>Windows PDB writer doesn't support SourceLink feature: '{0}'</value>
  </data>
+ <data name="SymWriterMetadataOverLimit" xml:space="preserve">
+ <value>Cannot emit native PDB for method '{0}' because its debug metadata size {1} is over the limit {2}.</value>
+ </data>
  <data name="RuleSetBadAttributeValue" xml:space="preserve">
  <value>The attribute {0} has an invalid value of {1}.</value>
  </data>

src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs

@@ -148,6 +148,16 @@ public void SerializeDebugInfo(IMethodBody methodBody, StandaloneSignatureHandle
 
  if (blob.Length > 0)
  {
+ const int limit = 0x10_000;
+ if (blob.Length > limit)
+ {
+ throw new SymUnmanagedWriterException(string.Format(
+ CodeAnalysisResources.SymWriterMetadataOverLimit,
+ methodBody.MethodDefinition,
+ blob.Length,
+ limit));
+ }
+
  _symWriter.DefineCustomMetadata(blob);
  }
 

src/Compilers/VisualBasic/Test/Emit/PDB/PDBTests.vb

@@ -208,6 +208,31 @@ End Class
  result.Diagnostics.Verify(Diagnostic(ERRID.ERR_DebugEntryPointNotSourceMethodDefinition))
  End Sub
 
+ <ConditionalFact(GetType(WindowsOnly), Reason:=ConditionalSkipReason.NativePdbRequiresDesktop)>
+ <WorkItem("https://github.com/dotnet/roslyn/issues/75237")>
+ Public Sub NativeWriterLimit()
+ Dim locals = Enumerable.Range(0, 14_000).
+ Select(Function(i) $"
+Dim local{i} As Integer = {i}
+M2(local{i})
+").
+ Join(Environment.NewLine)
+ Dim source = $"
+Namespace N
+Class C
+ Shared Sub M1()
+ {locals}
+ End Sub
+ Shared Sub M2(x As Integer)
+ End Sub
+End Class
+End Namespace
+"
+ ' Cannot emit native PDB for method 'Public Shared Sub M1()' because its debug metadata size 69328 is over the limit 65536.
+ CreateCompilation(source, options:=TestOptions.DebugDll).VerifyEmitDiagnostics(
+ Diagnostic(ERRID.ERR_PDBWritingFailed).WithArguments(String.Format(CodeAnalysisResources.SymWriterMetadataOverLimit, "Public Shared Sub M1()", 69328, 65536)).WithLocation(1, 1))
+ End Sub
+
 #End Region
 
  <ConditionalFact(GetType(WindowsOnly), Reason:=ConditionalSkipReason.NativePdbRequiresDesktop)>

src/Test/PdbUtilities/Writer/CustomMetadataSymUnmanagedWriter.cs

@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.DiaSymReader;
+
+namespace Roslyn.Test.PdbUtilities;
+
+internal sealed class CustomMetadataSymUnmanagedWriter(SymUnmanagedWriter target, byte[] customMetadata) : DelegatingSymUnmanagedWriter(target)
+{
+ private readonly byte[] _customMetadata = customMetadata;
+
+ public override void DefineCustomMetadata(byte[] metadata)
+ {
+ base.DefineCustomMetadata(_customMetadata);
+ }
+}