Fix Code Model's GetTypeFromFullName to better handle situations where...

Fix Code Model's GetTypeFromFullName to better handle situations where unsupported name formats are passed

`GetTypeFromFullName` first attempts to treat the specified type name as a metadata name. Failing
that, it parses the type name and tries to speculatively bind it. However, it was entirely possible
that a type name could be provided that we don't support, such as an assembly-qualified name. So, we
now check to see if the parsed type name includes an skipped token trivia (e.g. a trailing "Foo, 0.0.0.0")
and does not attempt to bind in that case. Otherwise, speculative binding could return something
non-sensical.

src/VisualStudio/CSharp/Impl/CodeModel/CSharpCodeModelService.cs

@@ -3027,6 +3027,15 @@ public override ITypeSymbol GetTypeSymbolFromFullName(string fullName, Compilati
             {
                 var parsedTypeName = SyntaxFactory.ParseTypeName(fullName);
 
+                // Check to see if the name we parsed has any skipped text. If it does, don't bother trying to
+                // speculatively bind it because we'll likely just get the wrong thing since we found a bunch
+                // of non-sensical tokens.
+
+                if (parsedTypeName.ContainsSkippedText)
+                {
+                    return null;
+                }
+
                 // If we couldn't get the name, we just grab the first tree in the compilation to
                 // speculatively bind at position zero. However, if there *aren't* any trees, we fork the
                 // compilation with an empty tree for the purposes of speculative binding.

src/VisualStudio/Core/Test/CodeModel/CSharp/RootCodeModelTests.vb

@@ -28,7 +28,7 @@ class Foo { }
 #End Region
 
         <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
-        Public Async Function TestDotNetNameFromLanguageSpecific() As Task
+        Public Async Function TestDotNetNameFromLanguageSpecific1() As Task
             Dim code =
 <code>
 using N.M;
@@ -49,6 +49,23 @@ namespace N
                 End Sub)
         End Function
 
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Async Function TestDotNetNameFromLanguageSpecific2() As Task
+            Await TestRootCodeModelWithCodeFile(<code></code>,
+                Sub(rootCodeModel)
+                    Dim dotNetName = rootCodeModel.DotNetNameFromLanguageSpecific("System.Collections.Generic.List<int>")
+                    Assert.Equal("System.Collections.Generic.List`1[System.Int32]", dotNetName)
+                End Sub)
+        End Function
+
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Async Function TestDotNetNameFromLanguageSpecificWithAssemblyQualifiedName() As Task
+            Await TestRootCodeModelWithCodeFile(<code></code>,
+                Sub(rootCodeModel)
+                    Assert.Throws(Of ArgumentException)(Sub() rootCodeModel.DotNetNameFromLanguageSpecific("System.Collections.Generic.List<int>, mscorlib"))
+                End Sub)
+        End Function
+
         <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
         Public Async Function TestExternalNamespaceChildren() As Task
             Dim code =

src/VisualStudio/Core/Test/CodeModel/VisualBasic/RootCodeModelTests.vb

@@ -231,7 +231,7 @@ End Namespace
 #End Region
 
         <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
-        Public Async Function TestDotNetNameFromLanguageSpecific() As Task
+        Public Async Function TestDotNetNameFromLanguageSpecific1() As Task
             Dim code =
 <code>
 Imports N.M
@@ -251,6 +251,23 @@ End Namespace
                 End Sub)
         End Function
 
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Async Function TestDotNetNameFromLanguageSpecific2() As Task
+            Await TestRootCodeModelWithCodeFile(<code></code>,
+                Sub(rootCodeModel)
+                    Dim dotNetName = rootCodeModel.DotNetNameFromLanguageSpecific("System.Collections.Generic.List(Of Integer)")
+                    Assert.Equal("System.Collections.Generic.List`1[System.Int32]", dotNetName)
+                End Sub)
+        End Function
+
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Async Function TestDotNetNameFromLanguageSpecificWithAssemblyQualifiedName() As Task
+            Await TestRootCodeModelWithCodeFile(<code></code>,
+                Sub(rootCodeModel)
+                    Assert.Throws(Of ArgumentException)(Sub() rootCodeModel.DotNetNameFromLanguageSpecific("System.Collections.Generic.List(Of Integer), mscorlib"))
+                End Sub)
+        End Function
+
         Protected Overrides ReadOnly Property LanguageName As String
             Get
                 Return LanguageNames.VisualBasic

src/VisualStudio/VisualBasic/Impl/CodeModel/VisualBasicCodeModelService.vb

@@ -3564,6 +3564,21 @@ Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.CodeModel
             If typeSymbol Is Nothing Then
                 Dim parsedTypeName = SyntaxFactory.ParseTypeName(fullName)
 
+                ' Check to see if the name we parsed has any skipped text. If it does, don't bother trying to
+                ' speculatively bind it because we'll likely just get the wrong thing since we found a bunch
+                ' of non-sensical tokens.
+
+                ' NOTE: There appears to be a VB parser issue where "ContainsSkippedText" does not return true
+                ' even when there is clearly skipped token trivia present. We work around this by for a particularly
+                ' common case by checking whether the trailing trivia contains any skipped token trivia.
+                ' https://github.com/dotnet/roslyn/issues/7182 has been filed for the parser issue.
+
+                If parsedTypeName.ContainsSkippedText OrElse
+                   parsedTypeName.GetTrailingTrivia().Any(SyntaxKind.SkippedTokensTrivia) Then
+
+                    Return Nothing
+                End If
+
                 ' If we couldn't get the name, we just grab the first tree in the compilation to
                 ' speculatively bind at position zero. However, if there *aren't* any trees, we fork the
                 ' compilation with an empty tree for the purposes of speculative binding.