Catch exceptions when writing XML doc files in VB (#13918)

This is the same fix as was implemented for C# in #13806, but for VB.

src/Compilers/CSharp/Portable/Compiler/DocumentationCommentCompiler.cs

@@ -88,9 +88,9 @@ public static void WriteDocumentationCommentXml(CSharpCompilation compilation, s
                     leaveOpen: true); // Don't close caller's stream.
             }
 
-            using (writer)
+            try
             {
-                try
+                using (writer)
                 {
                     var compiler = new DocumentationCommentCompiler(assemblyName ?? compilation.SourceAssembly.Name, compilation, writer, filterTree, filterSpanWithinTree,
                         processIncludes: true, isForSingleSymbol: false, diagnostics: diagnostics, cancellationToken: cancellationToken);
@@ -98,10 +98,10 @@ public static void WriteDocumentationCommentXml(CSharpCompilation compilation, s
                     Debug.Assert(compiler._indentDepth == 0);
                     writer?.Flush();
                 }
-                catch (Exception e)
-                {
-                    diagnostics.Add(ErrorCode.ERR_DocFileGen, Location.None, e.Message);
-                }
+            }
+            catch (Exception e)
+            {
+                diagnostics.Add(ErrorCode.ERR_DocFileGen, Location.None, e.Message);
             }
 
             if (filterTree != null)

src/Compilers/VisualBasic/Portable/Compilation/DocumentationComments/DocumentationCommentCompiler.vb

@@ -68,14 +68,19 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                     writer = New StreamWriter(xmlDocStream, New UTF8Encoding(True, False), bufferSize:=&H400, leaveOpen:=True)
                 End If
 
-                Using writer
-                    ' TODO: get preferred culture from compilation(?)
-                    Dim compiler As New DocumentationCommentCompiler(If(assemblyName, compilation.SourceAssembly.Name), compilation, writer, True, False,
+                Try
+                    Using writer
+                        ' TODO: get preferred culture from compilation(?)
+                        Dim compiler As New DocumentationCommentCompiler(If(assemblyName, compilation.SourceAssembly.Name), compilation, writer, True, False,
                             diagnostics, filterTree, filterSpanWithinTree, preferredCulture:=Nothing, cancellationToken:=cancellationToken)
 
-                    compiler.Visit(compilation.SourceAssembly.GlobalNamespace)
-                    Debug.Assert(compiler._writer.IndentDepth = 0)
-                End Using
+                        compiler.Visit(compilation.SourceAssembly.GlobalNamespace)
+                        Debug.Assert(compiler._writer.IndentDepth = 0)
+                        writer?.Flush()
+                    End Using
+                Catch ex As Exception
+                    diagnostics.Add(ERRID.ERR_DocFileGen, Location.None, ex.Message)
+                End Try
 
                 For Each tree In compilation.SyntaxTrees
                     MislocatedDocumentationCommentFinder.ReportUnprocessed(tree, filterSpanWithinTree, diagnostics, cancellationToken)

src/Compilers/VisualBasic/Portable/Errors/Errors.vb

@@ -1686,8 +1686,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         ERR_PeWritingFailure = 37256
 
         ERR_OptionMustBeAbsolutePath = 37257
+        ERR_DocFileGen = 37258
 
-        ' available 37258
         ERR_TupleTooFewElements = 37259
         ERR_TupleReservedMemberNameAnyPosition = 37260
         ERR_TupleReservedMemberName = 37261

src/Compilers/VisualBasic/Portable/VBResources.Designer.vb

@@ -2945,6 +2945,15 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End Get
         End Property
         
+        '''<summary>
+        '''  Looks up a localized string similar to Error writing to XML documentation file: {0}.
+        '''</summary>
+        Friend ReadOnly Property ERR_DocFileGen() As String
+            Get
+                Return ResourceManager.GetString("ERR_DocFileGen", resourceCulture)
+            End Get
+        End Property
+        
         '''<summary>
         '''  Looks up a localized string similar to &apos;{0}&apos; does not implement &apos;{1}&apos;..
         '''</summary>

src/Compilers/VisualBasic/Portable/VBResources.resx

@@ -5400,4 +5400,7 @@
   <data name="ERR_InvalidInstrumentationKind" xml:space="preserve">
     <value>Invalid instrumentation kind: {0}</value>
   </data>
-</root>
\ No newline at end of file
+  <data name="ERR_DocFileGen" xml:space="preserve">
+    <value>Error writing to XML documentation file: {0}</value>
+  </data>
+</root>

src/Compilers/VisualBasic/Test/Symbol/DocumentationComments/DocCommentTests.vb

@@ -9,6 +9,7 @@ Imports System.Xml.Linq
 Imports System.Text
 Imports System.IO
 Imports Roslyn.Test.Utilities
+Imports Microsoft.CodeAnalysis.VisualBasic.VisualBasicCompilation
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
     Public Class DocCommentTests
@@ -16,6 +17,44 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
 
         Private Shared ReadOnly s_optionsDiagnoseDocComments As VisualBasicParseOptions = VisualBasicParseOptions.Default.WithDocumentationMode(DocumentationMode.Diagnose)
 
+        <Fact>
+        Public Sub DocCommentWriteException()
+            Dim sources =
+<compilation name="DocCommentException">
+    <file name="a.vb">
+        <![CDATA[
+''' <summary>
+''' Doc comment for <see href="C" />
+''' </summary>
+Public Class C
+    ''' <summary>
+    ''' Doc comment for method M
+    ''' </summary>
+    Public Sub M()
+    End Sub
+End Class
+]]>
+    </file>
+</compilation>
+
+            Dim comp = CreateCompilationWithMscorlib(sources)
+            Dim diags = New DiagnosticBag()
+            Dim badStream = New BrokenStream()
+            badStream.BreakHow = BrokenStream.BreakHowType.ThrowOnWrite
+
+            DocumentationCommentCompiler.WriteDocumentationCommentXml(
+                comp,
+                assemblyName:=Nothing,
+                xmlDocStream:=badStream,
+                diagnostics:=diags,
+                cancellationToken:=Nothing)
+
+            AssertTheseDiagnostics(diags.ToReadOnlyAndFree(),
+                                   <errors><![CDATA[
+BC37258: Error writing to XML documentation file: I/O error occurred.
+                                   ]]></errors>)
+        End Sub
+
         <Fact>
         Public Sub NoXmlResolver()
             Dim sources =