enable quick-info for interpolated strings

src/EditorFeatures/CSharpTest/QuickInfo/SemanticQuickInfoSourceTests.cs

@@ -1267,6 +1267,34 @@ public void TestStringLiteral()
                 MainDescription("class System.String"));
         }
 
+        [WorkItem(1280, "https://github.com/dotnet/roslyn/issues/1280")]
+        [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
+        public void TestVerbatimStringLiteral()
+        {
+            TestInMethod(@"string f = @""cat""$$",
+                MainDescription("class System.String"));
+        }
+
+        [WorkItem(1280, "https://github.com/dotnet/roslyn/issues/1280")]
+        [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
+        public void TestInterpolatedStringLiteral()
+        {
+            TestInMethod(@"string f = $""cat""$$", MainDescription("class System.String"));
+            TestInMethod(@"string f = $""c$$at""", MainDescription("class System.String"));
+            TestInMethod(@"string f = $""$$cat""", MainDescription("class System.String"));
+            TestInMethod(@"string f = $""cat {1$$ + 2} dog""", MainDescription("struct System.Int32"));
+        }
+
+        [WorkItem(1280, "https://github.com/dotnet/roslyn/issues/1280")]
+        [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
+        public void TestVerbatimInterpolatedStringLiteral()
+        {
+            TestInMethod(@"string f = $@""cat""$$", MainDescription("class System.String"));
+            TestInMethod(@"string f = $@""c$$at""", MainDescription("class System.String"));
+            TestInMethod(@"string f = $@""$$cat""", MainDescription("class System.String"));
+            TestInMethod(@"string f = $@""cat {1$$ + 2} dog""", MainDescription("struct System.Int32"));
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
         public void TestCharLiteral()
         {

src/EditorFeatures/VisualBasicTest/QuickInfo/SemanticQuickInfoSourceTests.vb

@@ -149,6 +149,22 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.QuickInfo
              MainDescription("Class System.String"))
         End Sub
 
+        <WorkItem(1280, "https://github.com/dotnet/roslyn/issues/1280")>
+        <Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)>
+        Public Sub TestStringLiteral()
+            TestInClass("Dim i = ""cat""$$",
+             MainDescription("Class System.String"))
+        End Sub
+
+        <WorkItem(1280, "https://github.com/dotnet/roslyn/issues/1280")>
+        <Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)>
+        Public Sub TestInterpolatedStringLiteral()
+            TestInClass("Dim i = $""cat""$$", MainDescription("Class System.String"))
+            TestInClass("Dim i = $""c$$at""", MainDescription("Class System.String"))
+            TestInClass("Dim i = $""$$cat""", MainDescription("Class System.String"))
+            TestInClass("Dim i = $""cat {1$$ + 2} dog""", MainDescription("Structure System.Int32"))
+        End Sub
+
         <Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)>
         Public Sub TestListOfString()
             TestInClass("Dim l As $$List(Of String)",

src/Workspaces/CSharp/Portable/LanguageServices/CSharpSyntaxFactsService.cs

@@ -450,6 +450,10 @@ public bool IsLiteral(SyntaxToken token)
                 case SyntaxKind.NullKeyword:
                 case SyntaxKind.TrueKeyword:
                 case SyntaxKind.FalseKeyword:
+                case SyntaxKind.InterpolatedStringStartToken:
+                case SyntaxKind.InterpolatedStringEndToken:
+                case SyntaxKind.InterpolatedVerbatimStringStartToken:
+                case SyntaxKind.InterpolatedStringTextToken:
                     return true;
             }
 
@@ -1272,6 +1276,14 @@ public SyntaxNode GetBindableParent(SyntaxToken token)
                     }
                 }
 
+                // The inside of an interpolated string is treated as its own token so we
+                // need to force navigation to the parent expression syntax.
+                if (node is InterpolatedStringTextSyntax && parent is InterpolatedStringExpressionSyntax)
+                {
+                    node = parent;
+                    break;
+                }
+
                 // If this node is not parented by a name, we're done.
                 var name = parent as NameSyntax;
                 if (name == null)

src/Workspaces/VisualBasic/Portable/LanguageServices/VisualBasicSyntaxFactsService.vb

@@ -386,7 +386,24 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         End Function
 
         Public Function IsLiteral(token As SyntaxToken) As Boolean Implements ISyntaxFactsService.IsLiteral
-            Return SyntaxFacts.IsLiteralExpressionToken(CType(token.Kind, SyntaxKind))
+            Select Case token.Kind()
+                Case _
+                        SyntaxKind.IntegerLiteralToken,
+                        SyntaxKind.CharacterLiteralToken,
+                        SyntaxKind.DecimalLiteralToken,
+                        SyntaxKind.FloatingLiteralToken,
+                        SyntaxKind.DateLiteralToken,
+                        SyntaxKind.StringLiteralToken,
+                        SyntaxKind.DollarSignDoubleQuoteToken,
+                        SyntaxKind.DoubleQuoteToken,
+                        SyntaxKind.InterpolatedStringTextToken,
+                        SyntaxKind.TrueKeyword,
+                        SyntaxKind.FalseKeyword,
+                        SyntaxKind.NothingKeyword
+                    Return True
+            End Select
+
+            Return False
         End Function
 
         Public Function IsStringLiteral(token As SyntaxToken) As Boolean Implements ISyntaxFactsService.IsStringLiteral
@@ -1028,6 +1045,13 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                     End If
                 End If
 
+                ' The inside of an interpolated string is treated as its own token so we
+                ' need to force navigation to the parent expression syntax.
+                If TypeOf node Is InterpolatedStringTextSyntax AndAlso TypeOf parent Is InterpolatedStringExpressionSyntax Then
+                    node = parent
+                    Exit While
+                End If
+
                 ' If this node is not parented by a name, we're done.
                 Dim name = TryCast(parent, NameSyntax)
                 If name Is Nothing Then