VB implementation

src/Compilers/Test/Utilities/VisualBasic/CompilationTestUtils.vb

@@ -33,6 +33,19 @@ Friend Module CompilationUtils
         Return CreateEmptyCompilation(source, references, options, parseOptions, assemblyName)
     End Function
 
+    Public Function CreateCompilationWithIdentity(
+            identity As AssemblyIdentity,
+            source As BasicTestSource,
+            Optional references As IEnumerable(Of MetadataReference) = Nothing,
+            Optional targetFramework As TargetFramework = TargetFramework.StandardAndVBRuntime) As VisualBasicCompilation
+
+        Dim c = CreateCompilation(source, references, assemblyName:=identity.Name)
+        Assert.NotNull(c.Assembly) ' force creation Of SourceAssemblySymbol
+        DirectCast(c.Assembly, SourceAssemblySymbol).m_lazyIdentity = identity
+
+        Return c
+    End Function
+
     Public Function CreateEmptyCompilation(
             source As BasicTestSource,
             Optional references As IEnumerable(Of MetadataReference) = Nothing,

src/Compilers/Test/Utilities/VisualBasic/MockSymbols.vb

@@ -747,6 +747,13 @@ Friend Class MockModuleSymbol
     Public Overrides Function GetMetadata() As ModuleMetadata
         Return Nothing
     End Function
+
+    Friend NotOverridable Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+        Get
+            Return Nothing
+        End Get
+    End Property
+
 End Class
 
 Friend Class MockAssemblySymbol
@@ -861,4 +868,11 @@ Friend Class MockAssemblySymbol
     Public Overrides Function GetMetadata() As AssemblyMetadata
         Return Nothing
     End Function
+
+    Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+        Get
+            Return Nothing
+        End Get
+    End Property
+
 End Class

src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb

@@ -238,16 +238,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
-        ''' <summary>
-        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete attribute.
-        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
-        ''' </summary>
-        Friend NotOverridable Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
-            Get
-                Return Nothing
-            End Get
-        End Property
-
         ''' <summary>
         ''' Lookup a top level type referenced from metadata, names should be
         ''' compared case-sensitively.

src/Compilers/VisualBasic/Portable/Symbols/Metadata/PE/PEAssemblySymbol.vb

@@ -68,6 +68,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
 
         Private _lazyCachedCompilerFeatureRequiredDiagnosticInfo As DiagnosticInfo = ErrorFactory.EmptyDiagnosticInfo
 
+        Private _lazyObsoleteAttributeData As ObsoleteAttributeData = ObsoleteAttributeData.Uninitialized
+
         Friend Sub New(assembly As PEAssembly, documentationProvider As DocumentationProvider,
                        isLinked As Boolean, importOptions As MetadataImportOptions)
             Debug.Assert(assembly IsNot Nothing)
@@ -286,5 +288,30 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
                 Return MyBase.HasUnsupportedMetadata
             End Get
         End Property
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete/Experimental/... attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                If _lazyObsoleteAttributeData Is ObsoleteAttributeData.Uninitialized Then
+                    Interlocked.CompareExchange(_lazyObsoleteAttributeData, ComputeObsoleteAttributeData(), ObsoleteAttributeData.Uninitialized)
+                End If
+
+                Return _lazyObsoleteAttributeData
+            End Get
+        End Property
+
+        Private Function ComputeObsoleteAttributeData() As ObsoleteAttributeData
+            For Each attrData In GetAttributes()
+                If attrData.IsTargetAttribute(Me, AttributeDescription.ExperimentalAttribute) Then
+                    Return attrData.DecodeExperimentalAttribute()
+                End If
+            Next
+
+            Return Nothing
+        End Function
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Metadata/PE/PEModuleSymbol.vb

@@ -81,6 +81,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
 
         Private _lazyCachedCompilerFeatureRequiredDiagnosticInfo As DiagnosticInfo = ErrorFactory.EmptyDiagnosticInfo
 
+        Private _lazyObsoleteAttributeData As ObsoleteAttributeData = ObsoleteAttributeData.Uninitialized
+
         Friend Sub New(assemblySymbol As PEAssemblySymbol, [module] As PEModule, importOptions As MetadataImportOptions, ordinal As Integer)
             Me.New(DirectCast(assemblySymbol, AssemblySymbol), [module], importOptions, ordinal)
             Debug.Assert(ordinal >= 0)
@@ -507,5 +509,30 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
                 Return MyBase.HasUnsupportedMetadata
             End Get
         End Property
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete/Experimental/... attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                If _lazyObsoleteAttributeData Is ObsoleteAttributeData.Uninitialized Then
+                    Interlocked.CompareExchange(_lazyObsoleteAttributeData, ComputeObsoleteAttributeData(), ObsoleteAttributeData.Uninitialized)
+                End If
+
+                Return _lazyObsoleteAttributeData
+            End Get
+        End Property
+
+        Private Function ComputeObsoleteAttributeData() As ObsoleteAttributeData
+            For Each attrData In GetAttributes()
+                If attrData.IsTargetAttribute(Me, AttributeDescription.ExperimentalAttribute) Then
+                    Return attrData.DecodeExperimentalAttribute()
+                End If
+            Next
+
+            Return Nothing
+        End Function
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/MissingAssemblySymbol.vb

@@ -165,6 +165,17 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         Public Overrides Function GetMetadata() As AssemblyMetadata
             Return Nothing
         End Function
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete/Experimental/... attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                Return Nothing
+            End Get
+        End Property
+
     End Class
 
     ''' <summary>

src/Compilers/VisualBasic/Portable/Symbols/MissingModuleSymbol.vb

@@ -171,6 +171,13 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         Public Overrides Function GetMetadata() As ModuleMetadata
             Return Nothing
         End Function
+
+        Friend NotOverridable Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                Return Nothing
+            End Get
+        End Property
+
     End Class
 
     Friend Class MissingModuleSymbolWithName

src/Compilers/VisualBasic/Portable/Symbols/ModuleSymbol.vb

@@ -293,16 +293,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         ''' </summary>
         Friend MustOverride ReadOnly Property MightContainExtensionMethods As Boolean
 
-        ''' <summary>
-        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete attribute.
-        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
-        ''' </summary>
-        Friend NotOverridable Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
-            Get
-                Return Nothing
-            End Get
-        End Property
-
 #Region "IModuleSymbol"
         Private ReadOnly Property IModuleSymbol_GlobalNamespace As INamespaceSymbol Implements IModuleSymbol.GlobalNamespace
             Get

src/Compilers/VisualBasic/Portable/Symbols/ObsoleteAttributeHelpers.vb

@@ -46,13 +46,13 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         ''' symbol's Obsoleteness is Unknown. False, if we are certain that no symbol in the parent
         ''' hierarchy is Obsolete.
         ''' </returns>
-        Private Shared Function GetObsoleteContextState(symbol As Symbol, forceComplete As Boolean) As ThreeState
+        Private Shared Function GetObsoleteContextState(symbol As Symbol, forceComplete As Boolean, getStateFromSymbol As Func(Of Symbol, ThreeState)) As ThreeState
             While symbol IsNot Nothing
                 If forceComplete Then
                     symbol.ForceCompleteObsoleteAttribute()
                 End If
 
-                Dim state = symbol.ObsoleteState
+                Dim state = getStateFromSymbol(symbol)
                 If state <> ThreeState.False Then
                     Return state
                 End If
@@ -72,11 +72,39 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             Debug.Assert(context IsNot Nothing)
             Debug.Assert(symbol IsNot Nothing)
 
+            Dim namedType = TryCast(symbol, NamedTypeSymbol)
+            If namedType IsNot Nothing AndAlso
+                IsExperimentalSymbol(namedType) Then
+
+                ' Skip for System.Diagnostics.CodeAnalysis.ExperimentalAttribute to mitigate cycles
+                Return ObsoleteDiagnosticKind.NotObsolete
+            End If
+
+            Dim method = TryCast(symbol, MethodSymbol)
+            If method IsNot Nothing AndAlso
+                    method.MethodKind = MethodKind.Constructor AndAlso
+                    IsExperimentalSymbol(method.ContainingType) Then
+
+                ' Skip for constructors of System.Diagnostics.CodeAnalysis.ExperimentalAttribute to mitigate cycles
+                Return ObsoleteDiagnosticKind.NotObsolete
+            End If
+
+            Debug.Assert(symbol.ContainingModule Is Nothing OrElse symbol.ContainingModule.ObsoleteKind <> ObsoleteAttributeKind.Uninitialized)
+            Debug.Assert(symbol.ContainingAssembly Is Nothing OrElse symbol.ContainingAssembly.ObsoleteKind <> ObsoleteAttributeKind.Uninitialized)
+
+            If symbol.ContainingModule?.ObsoleteKind = ObsoleteAttributeKind.Experimental OrElse
+                symbol.ContainingAssembly?.ObsoleteKind = ObsoleteAttributeKind.Experimental Then
+
+                Return GetExperimentalDiagnosticKind(context, forceComplete)
+            End If
+
             Select Case symbol.ObsoleteKind
                 Case ObsoleteAttributeKind.None
                     Return ObsoleteDiagnosticKind.NotObsolete
-                Case ObsoleteAttributeKind.WindowsExperimental, ObsoleteAttributeKind.Experimental
+                Case ObsoleteAttributeKind.WindowsExperimental
                     Return ObsoleteDiagnosticKind.Diagnostic
+                Case ObsoleteAttributeKind.Experimental
+                    Return GetExperimentalDiagnosticKind(context, forceComplete)
                 Case ObsoleteAttributeKind.Uninitialized
                     ' If we haven't cracked attributes on the symbol at all or we haven't
                     ' cracked attribute arguments enough to be able to report diagnostics for
@@ -85,7 +113,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                     Return ObsoleteDiagnosticKind.Lazy
             End Select
 
-            Select Case GetObsoleteContextState(context, forceComplete)
+            Select Case GetObsoleteContextState(context, forceComplete, getStateFromSymbol:=Function(s) s.ObsoleteState)
                 Case ThreeState.False
                     Return ObsoleteDiagnosticKind.Diagnostic
                 Case ThreeState.True
@@ -99,12 +127,36 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Select
         End Function
 
+        Private Shared Function IsExperimentalSymbol(namedType As NamedTypeSymbol) As Boolean
+            Return namedType IsNot Nothing AndAlso
+                namedType.Arity = 0 AndAlso
+                namedType.HasNameQualifier("System.Diagnostics.CodeAnalysis", StringComparison.Ordinal) AndAlso
+                namedType.Name.Equals("ExperimentalAttribute", StringComparison.Ordinal)
+        End Function
+
+        Private Shared Function GetExperimentalDiagnosticKind(containingMember As Symbol, forceComplete As Boolean) As ObsoleteDiagnosticKind
+
+            Select Case GetObsoleteContextState(containingMember, forceComplete, getStateFromSymbol:=Function(s) s.ExperimentalState)
+                Case ThreeState.False
+                    Return ObsoleteDiagnosticKind.Diagnostic
+                Case ThreeState.True
+                    ' If we are in a context that is already experimental, there is no point reporting
+                    ' more experimental diagnostics.
+                    Return ObsoleteDiagnosticKind.Suppressed
+                Case Else
+                    ' If the context is unknown, then store the symbol so that we can do this check at a
+                    ' later stage
+                    Return ObsoleteDiagnosticKind.LazyPotentiallySuppressed
+            End Select
+        End Function
+
         ''' <summary>
         ''' Create a diagnostic for the given symbol. This could be an error or a warning based on
         ''' the ObsoleteAttribute's arguments.
         ''' </summary>
         Friend Shared Function CreateObsoleteDiagnostic(symbol As Symbol) As DiagnosticInfo
-            Dim data = symbol.ObsoleteAttributeData
+            Dim data = If(If(symbol.ObsoleteAttributeData, symbol.ContainingModule.ObsoleteAttributeData), symbol.ContainingAssembly.ObsoleteAttributeData)
+
             Debug.Assert(data IsNot Nothing)
 
             If data Is Nothing Then

src/Compilers/VisualBasic/Portable/Symbols/Retargeting/RetargetingAssemblySymbol.vb

@@ -268,5 +268,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Retargeting
         Public Overrides Function GetMetadata() As AssemblyMetadata
             Return _underlyingAssembly.GetMetadata()
         End Function
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete/Experimental/... attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                Return _underlyingAssembly.ObsoleteAttributeData
+            End Get
+        End Property
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Retargeting/RetargetingModuleSymbol.vb

@@ -290,5 +290,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Retargeting
         Public Overrides Function GetMetadata() As ModuleMetadata
             Return _underlyingModule.GetMetadata()
         End Function
+
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                Return _underlyingModule.ObsoleteAttributeData
+            End Get
+        End Property
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Source/SourceAssemblySymbol.vb

@@ -1092,6 +1092,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 arguments.GetOrCreateData(Of CommonAssemblyWellKnownAttributeData)().RuntimeCompatibilityWrapNonExceptionThrows = True
             ElseIf attrData.IsTargetAttribute(Me, AttributeDescription.DebuggableAttribute) Then
                 arguments.GetOrCreateData(Of CommonAssemblyWellKnownAttributeData)().HasDebuggableAttribute = True
+            ElseIf attrData.IsTargetAttribute(Me, AttributeDescription.ExperimentalAttribute) Then
+                arguments.GetOrCreateData(Of CommonAssemblyWellKnownAttributeData)().ObsoleteAttributeData = attrData.DecodeExperimentalAttribute()
             Else
                 Dim signature As Integer = attrData.GetTargetAttributeSignatureIndex(Me, AttributeDescription.AssemblyAlgorithmIdAttribute)
 
@@ -1780,5 +1782,20 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 Return _compilation
             End Get
         End Property
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                ' <assembly: Experimental> may have been specified in the assembly or one of the modules
+                Dim result = If(GetSourceDecodedWellKnownAttributeData()?.ObsoleteAttributeData, GetNetModuleDecodedWellKnownAttributeData()?.ObsoleteAttributeData)
+
+                Debug.Assert(result Is Nothing OrElse result.Kind = ObsoleteAttributeKind.Experimental)
+                Return result
+            End Get
+        End Property
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Source/SourceModuleSymbol.vb

@@ -1116,6 +1116,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 End If
             ElseIf attrData.IsTargetAttribute(Me, AttributeDescription.DebuggableAttribute) Then
                 arguments.GetOrCreateData(Of CommonModuleWellKnownAttributeData).HasDebuggableAttribute = True
+            ElseIf attrData.IsTargetAttribute(Me, AttributeDescription.ExperimentalAttribute) Then
+                arguments.GetOrCreateData(Of CommonModuleWellKnownAttributeData).ObsoleteAttributeData = attrData.DecodeObsoleteAttribute(ObsoleteAttributeKind.Experimental)
             End If
 
             MyBase.DecodeWellKnownAttribute(arguments)
@@ -1220,5 +1222,17 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         Public Overrides Function GetMetadata() As ModuleMetadata
             Return Nothing
         End Function
+
+        ''' <summary>
+        ''' Returns data decoded from Obsolete attribute or null if there is no Obsolete/Experimental/... attribute.
+        ''' This property returns ObsoleteAttributeData.Uninitialized if attribute arguments haven't been decoded yet.
+        ''' </summary>
+        Friend Overrides ReadOnly Property ObsoleteAttributeData As ObsoleteAttributeData
+            Get
+                Dim data = GetDecodedWellKnownAttributeData()
+                Return If(data IsNot Nothing, data.ObsoleteAttributeData, Nothing)
+            End Get
+        End Property
+
     End Class
 End Namespace