Adding a type parameter for ExpressionSyntax

src/Features/CSharp/Portable/SplitIntoNestedIfStatements/CSharpMergeNestedIfStatementsCodeRefactoringProvider.cs

@@ -10,7 +10,7 @@ namespace Microsoft.CodeAnalysis.CSharp.SplitIntoNestedIfStatements
 {
     [ExportCodeRefactoringProvider(LanguageNames.CSharp, Name = PredefinedCodeRefactoringProviderNames.MergeNestedIfStatements), Shared]
     internal sealed class CSharpMergeNestedIfStatementsCodeRefactoringProvider
-        : AbstractMergeNestedIfStatementsCodeRefactoringProvider<IfStatementSyntax>
+        : AbstractMergeNestedIfStatementsCodeRefactoringProvider<IfStatementSyntax, ExpressionSyntax>
     {
         protected override string IfKeywordText => SyntaxFacts.GetText(SyntaxKind.IfKeyword);
 
@@ -31,9 +31,10 @@ protected override ImmutableArray<SyntaxNode> GetElseClauses(IfStatementSyntax i
             return ImmutableArray.Create<SyntaxNode>(ifStatement.Else);
         }
 
-        protected override IfStatementSyntax MergeIfStatements(IfStatementSyntax outerIfStatement, IfStatementSyntax innerIfStatement, SyntaxNode condition)
+        protected override IfStatementSyntax MergeIfStatements(
+            IfStatementSyntax outerIfStatement, IfStatementSyntax innerIfStatement, ExpressionSyntax condition)
         {
-            return outerIfStatement.WithCondition((ExpressionSyntax)condition).WithStatement(innerIfStatement.Statement);
+            return outerIfStatement.WithCondition(condition).WithStatement(innerIfStatement.Statement);
         }
     }
 }

src/Features/Core/Portable/SplitIntoNestedIfStatements/AbstractMergeNestedIfStatementsCodeRefactoringProvider.cs

@@ -18,8 +18,9 @@
 namespace Microsoft.CodeAnalysis.SplitIntoNestedIfStatements
 {
     internal abstract class AbstractMergeNestedIfStatementsCodeRefactoringProvider<
-        TIfStatementSyntax> : CodeRefactoringProvider
+        TIfStatementSyntax, TExpressionSyntax> : CodeRefactoringProvider
         where TIfStatementSyntax : SyntaxNode
+        where TExpressionSyntax : SyntaxNode
     {
         protected abstract string IfKeywordText { get; }
 
@@ -27,7 +28,8 @@ internal abstract class AbstractMergeNestedIfStatementsCodeRefactoringProvider<
 
         protected abstract ImmutableArray<SyntaxNode> GetElseClauses(TIfStatementSyntax ifStatement);
 
-        protected abstract TIfStatementSyntax MergeIfStatements(TIfStatementSyntax outerIfStatement, TIfStatementSyntax innerIfStatement, SyntaxNode condition);
+        protected abstract TIfStatementSyntax MergeIfStatements(
+            TIfStatementSyntax outerIfStatement, TIfStatementSyntax innerIfStatement, TExpressionSyntax condition);
 
         public sealed override async Task ComputeRefactoringsAsync(CodeRefactoringContext context)
         {
@@ -61,7 +63,7 @@ private async Task<Document> FixAsync(Document document, TextSpan span, ISyntaxF
             Contract.ThrowIfFalse(IsTokenOfIfStatement(token, out var ifStatement));
             Contract.ThrowIfFalse(IsFirstStatementOfIfStatement(syntaxFacts, ifStatement, out var parentIfStatement));
 
-            var newCondition = document.GetLanguageService<SyntaxGenerator>().LogicalAndExpression(
+            var newCondition = (TExpressionSyntax)document.GetLanguageService<SyntaxGenerator>().LogicalAndExpression(
                 syntaxFacts.GetIfStatementCondition(parentIfStatement),
                 syntaxFacts.GetIfStatementCondition(ifStatement));
 

src/Features/VisualBasic/Portable/SplitIntoNestedIfStatements/VisualBasicMergeNestedIfStatementsCodeRefactoringProvider.vb

@@ -9,7 +9,7 @@ Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 Namespace Microsoft.CodeAnalysis.VisualBasic.SplitIntoNestedIfStatements
     <ExportCodeRefactoringProvider(LanguageNames.VisualBasic, Name:=PredefinedCodeRefactoringProviderNames.MergeNestedIfStatements), [Shared]>
     Friend NotInheritable Class VisualBasicMergeNestedIfStatementsCodeRefactoringProvider
-        Inherits AbstractMergeNestedIfStatementsCodeRefactoringProvider(Of MultiLineIfBlockSyntax)
+        Inherits AbstractMergeNestedIfStatementsCodeRefactoringProvider(Of MultiLineIfBlockSyntax, ExpressionSyntax)
 
         Protected Overrides ReadOnly Property IfKeywordText As String = SyntaxFacts.GetText(SyntaxKind.IfKeyword)
 
@@ -27,8 +27,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.SplitIntoNestedIfStatements
             Return ImmutableArray.ToImmutableArray(Of SyntaxNode)(ifStatement.ElseIfBlocks).Add(ifStatement.ElseBlock)
         End Function
 
-        Protected Overrides Function MergeIfStatements(outerIfBlock As MultiLineIfBlockSyntax, innerIfBlock As MultiLineIfBlockSyntax, condition As SyntaxNode) As MultiLineIfBlockSyntax
-            Return outerIfBlock.WithIfStatement(outerIfBlock.IfStatement.WithCondition(DirectCast(condition, ExpressionSyntax))) _
+        Protected Overrides Function MergeIfStatements(outerIfBlock As MultiLineIfBlockSyntax,
+                                                       innerIfBlock As MultiLineIfBlockSyntax,
+                                                       condition As ExpressionSyntax) As MultiLineIfBlockSyntax
+            Return outerIfBlock.WithIfStatement(outerIfBlock.IfStatement.WithCondition(condition)) _
                                .WithStatements(innerIfBlock.Statements)
         End Function
     End Class