Switch to using a string instead of a full diagnostic.

src/Features/CSharp/Portable/AddImport/CSharpAddImportCodeFixProvider.cs

@@ -174,11 +174,11 @@ protected override bool CanAddImport(SyntaxNode node, CancellationToken cancella
         }
 
         protected override bool CanAddImportForMethod(
-            Diagnostic diagnostic, ISyntaxFactsService syntaxFacts, SyntaxNode node, out SimpleNameSyntax nameNode)
+            string diagnosticId, ISyntaxFactsService syntaxFacts, SyntaxNode node, out SimpleNameSyntax nameNode)
         {
             nameNode = null;
 
-            switch (diagnostic.Id)
+            switch (diagnosticId)
             {
                 case CS7036:
                 case CS0428:
@@ -264,18 +264,18 @@ protected override bool CanAddImport(SyntaxNode node, CancellationToken cancella
             return true;
         }
 
-        protected override bool CanAddImportForDeconstruct(Diagnostic diagnostic, SyntaxNode node)
-            => diagnostic.Id == CS8129;
+        protected override bool CanAddImportForDeconstruct(string diagnosticId, SyntaxNode node)
+            => diagnosticId == CS8129;
 
-        protected override bool CanAddImportForNamespace(Diagnostic diagnostic, SyntaxNode node, out SimpleNameSyntax nameNode)
+        protected override bool CanAddImportForNamespace(string diagnosticId, SyntaxNode node, out SimpleNameSyntax nameNode)
         {
             nameNode = null;
             return false;
         }
 
-        protected override bool CanAddImportForQuery(Diagnostic diagnostic, SyntaxNode node)
+        protected override bool CanAddImportForQuery(string diagnosticId, SyntaxNode node)
         {
-            if (diagnostic.Id != CS1935)
+            if (diagnosticId != CS1935)
             {
                 return false;
             }
@@ -283,10 +283,10 @@ protected override bool CanAddImportForQuery(Diagnostic diagnostic, SyntaxNode n
             return node.AncestorsAndSelf().Any(n => n is QueryExpressionSyntax && !(n.Parent is QueryContinuationSyntax));
         }
 
-        protected override bool CanAddImportForType(Diagnostic diagnostic, SyntaxNode node, out SimpleNameSyntax nameNode)
+        protected override bool CanAddImportForType(string diagnosticId, SyntaxNode node, out SimpleNameSyntax nameNode)
         {
             nameNode = null;
-            switch (diagnostic.Id)
+            switch (diagnosticId)
             {
                 case CS0103:
                 case CS0246:

src/Features/Core/Portable/AddImport/AbstractAddImportCodeFixProvider.cs

@@ -41,11 +41,11 @@ internal abstract partial class AbstractAddImportCodeFixProvider<TSimpleNameSynt
         }
 
         protected abstract bool CanAddImport(SyntaxNode node, CancellationToken cancellationToken);
-        protected abstract bool CanAddImportForMethod(Diagnostic diagnostic, ISyntaxFactsService syntaxFacts, SyntaxNode node, out TSimpleNameSyntax nameNode);
-        protected abstract bool CanAddImportForNamespace(Diagnostic diagnostic, SyntaxNode node, out TSimpleNameSyntax nameNode);
-        protected abstract bool CanAddImportForDeconstruct(Diagnostic diagnostic, SyntaxNode node);
-        protected abstract bool CanAddImportForQuery(Diagnostic diagnostic, SyntaxNode node);
-        protected abstract bool CanAddImportForType(Diagnostic diagnostic, SyntaxNode node, out TSimpleNameSyntax nameNode);
+        protected abstract bool CanAddImportForMethod(string diagnosticId, ISyntaxFactsService syntaxFacts, SyntaxNode node, out TSimpleNameSyntax nameNode);
+        protected abstract bool CanAddImportForNamespace(string diagnosticId, SyntaxNode node, out TSimpleNameSyntax nameNode);
+        protected abstract bool CanAddImportForDeconstruct(string diagnosticId, SyntaxNode node);
+        protected abstract bool CanAddImportForQuery(string diagnosticId, SyntaxNode node);
+        protected abstract bool CanAddImportForType(string diagnosticId, SyntaxNode node, out TSimpleNameSyntax nameNode);
 
         protected abstract ISet<INamespaceSymbol> GetImportNamespacesInScope(SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken);
         protected abstract ITypeSymbol GetDeconstructInfo(SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken);
@@ -99,7 +99,7 @@ private async Task<int> HandleDiagnosticAsync(CodeFixContext context, Diagnostic
                         if (this.CanAddImport(node, cancellationToken))
                         {
                             var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
-                            var allSymbolReferences = await FindResultsAsync(document, semanticModel, diagnostic, node, cancellationToken).ConfigureAwait(false);
+                            var allSymbolReferences = await FindResultsAsync(document, semanticModel, diagnostic.Id, node, cancellationToken).ConfigureAwait(false);
 
                             // Nothing found at all. No need to proceed.
                             foreach (var reference in allSymbolReferences)
@@ -150,7 +150,7 @@ private IPackageInstallerService GetPackageInstallerService(Document document)
         }
 
         private async Task<ImmutableArray<Reference>> FindResultsAsync(
-            Document document, SemanticModel semanticModel, Diagnostic diagnostic, SyntaxNode node, CancellationToken cancellationToken)
+            Document document, SemanticModel semanticModel, string diagnosticId, SyntaxNode node, CancellationToken cancellationToken)
         {
             // Caches so we don't produce the same data multiple times while searching 
             // all over the solution.
@@ -158,7 +158,7 @@ private IPackageInstallerService GetPackageInstallerService(Document document)
             var projectToAssembly = new ConcurrentDictionary<Project, AsyncLazy<IAssemblySymbol>>(concurrencyLevel: 2, capacity: project.Solution.ProjectIds.Count);
             var referenceToCompilation = new ConcurrentDictionary<PortableExecutableReference, Compilation>(concurrencyLevel: 2, capacity: project.Solution.Projects.Sum(p => p.MetadataReferences.Count));
 
-            var finder = new SymbolReferenceFinder(this, document, semanticModel, diagnostic, node, cancellationToken);
+            var finder = new SymbolReferenceFinder(this, document, semanticModel, diagnosticId, node, cancellationToken);
 
             // Look for exact matches first:
             var exactReferences = await FindResultsAsync(projectToAssembly, referenceToCompilation, project, finder, exact: true, cancellationToken: cancellationToken).ConfigureAwait(false);

src/Features/Core/Portable/AddImport/SymbolReferenceFinder.cs

@@ -20,7 +20,7 @@ private partial class SymbolReferenceFinder
         {
             private const string AttributeSuffix = nameof(Attribute);
 
-            private readonly Diagnostic _diagnostic;
+            private readonly string _diagnosticId;
             private readonly Document _document;
             private readonly SemanticModel _semanticModel;
 
@@ -35,13 +35,13 @@ private partial class SymbolReferenceFinder
             public SymbolReferenceFinder(
                 AbstractAddImportCodeFixProvider<TSimpleNameSyntax> owner,
                 Document document, SemanticModel semanticModel,
-                Diagnostic diagnostic, SyntaxNode node,
+                string diagnosticId, SyntaxNode node,
                 CancellationToken cancellationToken)
             {
                 _owner = owner;
                 _document = document;
                 _semanticModel = semanticModel;
-                _diagnostic = diagnostic;
+                _diagnosticId = diagnosticId;
                 _node = node;
 
                 _containingType = semanticModel.GetEnclosingNamedType(node.SpanStart, cancellationToken);
@@ -155,7 +155,7 @@ private ImmutableArray<SymbolReference> DeDupeAndSortReferences(ImmutableArray<S
             private async Task<ImmutableArray<SymbolReference>> GetReferencesForMatchingTypesAsync(SearchScope searchScope)
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
-                if (!_owner.CanAddImportForType(_diagnostic, _node, out var nameNode))
+                if (!_owner.CanAddImportForType(_diagnosticId, _node, out var nameNode))
                 {
                     return ImmutableArray<SymbolReference>.Empty;
                 }
@@ -223,7 +223,7 @@ private async Task<ImmutableArray<SymbolReference>> GetReferencesForMatchingType
                 SearchScope searchScope)
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
-                if (_owner.CanAddImportForNamespace(_diagnostic, _node, out var nameNode))
+                if (_owner.CanAddImportForNamespace(_diagnosticId, _node, out var nameNode))
                 {
                     _syntaxFacts.GetNameAndArityOfSimpleName(nameNode, out var name, out var arity);
 
@@ -250,7 +250,7 @@ private async Task<ImmutableArray<SymbolReference>> GetReferencesForMatchingType
                 SearchScope searchScope)
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
-                if (_owner.CanAddImportForMethod(_diagnostic, _syntaxFacts, _node, out var nameNode) &&
+                if (_owner.CanAddImportForMethod(_diagnosticId, _syntaxFacts, _node, out var nameNode) &&
                     nameNode != null)
                 {
                         // We have code like "Color.Black".  "Color" bound to a 'Color Color' property, and
@@ -310,7 +310,7 @@ private bool HasAccessibleStaticFieldOrProperty(INamedTypeSymbol namedType, stri
             private async Task<ImmutableArray<SymbolReference>> GetReferencesForMatchingExtensionMethodsAsync(SearchScope searchScope)
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
-                if (_owner.CanAddImportForMethod(_diagnostic, _syntaxFacts, _node, out var nameNode) &&
+                if (_owner.CanAddImportForMethod(_diagnosticId, _syntaxFacts, _node, out var nameNode) &&
                     nameNode != null)
                 {
                     searchScope.CancellationToken.ThrowIfCancellationRequested();
@@ -368,7 +368,7 @@ private async Task<ImmutableArray<SymbolReference>> GetReferencesForMatchingExte
             private async Task<ImmutableArray<SymbolReference>> GetReferencesForCollectionInitializerMethodsAsync(SearchScope searchScope)
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
-                if (!_owner.CanAddImportForMethod(_diagnostic, _syntaxFacts, _node, out var nameNode))
+                if (!_owner.CanAddImportForMethod(_diagnosticId, _syntaxFacts, _node, out var nameNode))
                 {
                     return ImmutableArray<SymbolReference>.Empty;
                 }
@@ -403,7 +403,7 @@ private async Task<ImmutableArray<SymbolReference>> GetReferencesForQueryPattern
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
 
-                if (_owner.CanAddImportForQuery(_diagnostic, _node))
+                if (_owner.CanAddImportForQuery(_diagnosticId, _node))
                 {
                     var type = _owner.GetQueryClauseInfo(_semanticModel, _node, searchScope.CancellationToken);
                     if (type != null)
@@ -426,7 +426,7 @@ private async Task<ImmutableArray<SymbolReference>> GetReferencesForDeconstructA
             {
                 searchScope.CancellationToken.ThrowIfCancellationRequested();
 
-                if (_owner.CanAddImportForDeconstruct(_diagnostic, _node))
+                if (_owner.CanAddImportForDeconstruct(_diagnosticId, _node))
                 {
                     var type = _owner.GetDeconstructInfo(_semanticModel, _node, searchScope.CancellationToken);
                     if (type != null)

src/Features/Core/Portable/AddImport/SymbolReferenceFinder_PackageAssemblySearch.cs

@@ -23,7 +23,7 @@ private partial class SymbolReferenceFinder
                     return;
                 }
 
-                if (!_owner.CanAddImportForType(_diagnostic, _node, out var nameNode))
+                if (!_owner.CanAddImportForType(_diagnosticId, _node, out var nameNode))
                 {
                     return;
                 }

src/Features/VisualBasic/Portable/AddImport/VisualBasicAddImportCodeFixProvider.vb

@@ -120,11 +120,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.AddImport
         End Function
 
         Protected Overrides Function CanAddImportForMethod(
-                diagnostic As Diagnostic,
+                diagnosticId As String,
                 syntaxFacts As ISyntaxFactsService,
                 node As SyntaxNode,
                 ByRef nameNode As SimpleNameSyntax) As Boolean
-            Select Case diagnostic.Id
+            Select Case diagnosticId
                 Case BC30456, BC30390, BC42309, BC30451
                     Exit Select
                 Case BC30512
@@ -177,8 +177,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.AddImport
             Return True
         End Function
 
-        Protected Overrides Function CanAddImportForNamespace(diagnostic As Diagnostic, node As SyntaxNode, ByRef nameNode As SimpleNameSyntax) As Boolean
-            Select Case diagnostic.Id
+        Protected Overrides Function CanAddImportForNamespace(diagnosticId As String, node As SyntaxNode, ByRef nameNode As SimpleNameSyntax) As Boolean
+            Select Case diagnosticId
                 Case BC30002, BC30451
                     Exit Select
                 Case Else
@@ -188,13 +188,13 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.AddImport
             Return CanAddImportForTypeOrNamespaceCore(node, nameNode)
         End Function
 
-        Protected Overrides Function CanAddImportForDeconstruct(diagnostic As Diagnostic, node As SyntaxNode) As Boolean
+        Protected Overrides Function CanAddImportForDeconstruct(diagnosticId As String, node As SyntaxNode) As Boolean
             ' Not supported yet.
             Return False
         End Function
 
-        Protected Overrides Function CanAddImportForQuery(diagnostic As Diagnostic, node As SyntaxNode) As Boolean
-            If diagnostic.Id <> BC36593 Then
+        Protected Overrides Function CanAddImportForQuery(diagnosticId As String, node As SyntaxNode) As Boolean
+            If diagnosticId <> BC36593 Then
                 Return False
             End If
 
@@ -208,8 +208,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.AddImport
         End Function
 
         Protected Overrides Function CanAddImportForType(
-                diagnostic As Diagnostic, node As SyntaxNode, ByRef nameNode As SimpleNameSyntax) As Boolean
-            Select Case diagnostic.Id
+                diagnosticId As String, node As SyntaxNode, ByRef nameNode As SimpleNameSyntax) As Boolean
+            Select Case diagnosticId
                 Case BC30002, BC30451, BC32042, BC32045, BC30389, BC31504, BC36610, BC30182
                     Exit Select
                 Case BC42309