Add else if support to RCS1211

ChangeLog.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Add SECURITY.md ([#1147](https://github.com/josefpihrt/roslynator/pull/1147))
+- [RCS1211](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1211) will suggest removing unecessary 'else if' clauses ([#1155](https://github.com/josefpihrt/roslynator/pull/1155))
 
 ### Fixed
 

src/Analyzers/CSharp/Analysis/RemoveUnnecessaryElseAnalyzer.cs

@@ -47,9 +47,6 @@ public static void Analyze(SyntaxNodeAnalysisContext context)
 
     private static bool IsFixable(ElseClauseSyntax elseClause, SemanticModel semanticModel)
     {
-        if (elseClause.Statement?.IsKind(SyntaxKind.IfStatement) != false)
-            return false;
-
         if (elseClause.Parent is not IfStatementSyntax ifStatement)
             return false;
 
@@ -61,22 +58,19 @@ private static bool IsFixable(ElseClauseSyntax elseClause, SemanticModel semanti
         if (ifStatementStatement is not BlockSyntax ifBlock)
             return CSharpFacts.IsJumpStatement(ifStatementStatement.Kind());
 
-        if (elseClause.Statement is BlockSyntax elseBlock)
-        {
-            if (LocalDeclaredVariablesOverlap(elseBlock, ifBlock, semanticModel))
-                return false;
-
-            if (ifStatement.Parent is SwitchSectionSyntax { Parent: SwitchStatementSyntax switchStatement }
-                && SwitchLocallyDeclaredVariablesHelper.BlockDeclaredVariablesOverlapWithOtherSwitchSections(elseBlock, switchStatement, semanticModel))
-            {
-                return false;
-            }
-        }
-
         StatementSyntax lastStatementInIf = ifBlock.Statements.LastOrDefault();
 
-        return lastStatementInIf is not null
-            && CSharpFacts.IsJumpStatement(lastStatementInIf.Kind());
+        if (lastStatementInIf is null || !CSharpFacts.IsJumpStatement(lastStatementInIf.Kind()))
+            return false;
+
+        if (elseClause.Statement is not BlockSyntax elseBlock)
+            return true;
+
+        if (LocalDeclaredVariablesOverlap(elseBlock, ifBlock, semanticModel))
+            return false;
+
+        return ifStatement.Parent is not SwitchSectionSyntax { Parent: SwitchStatementSyntax switchStatement }
+            || !SwitchLocallyDeclaredVariablesHelper.BlockDeclaredVariablesOverlapWithOtherSwitchSections(elseBlock, switchStatement, semanticModel);
     }
 
     private static bool LocalDeclaredVariablesOverlap(BlockSyntax elseBlock, BlockSyntax ifBlock, SemanticModel semanticModel)

src/Tests/Analyzers.Tests/RCS1211RemoveUnnecessaryElseTests.cs

@@ -46,6 +46,47 @@ int M(bool flag)
 ");
     }
 
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.RemoveUnnecessaryElse)]
+    public async Task Test_UnnecessaryElseIf_Removed()
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+class C
+{
+    int M(bool flag, bool flag2)
+    {
+        if (flag)
+        {
+            return 1;
+        }
+        [|else|] if (flag2)
+        {
+            return 0;
+        }
+
+        return 2;
+    }
+}
+", @"
+class C
+{
+    int M(bool flag, bool flag2)
+    {
+        if (flag)
+        {
+            return 1;
+        }
+
+        if (flag2)
+        {
+            return 0;
+        }
+
+        return 2;
+    }
+}
+");
+    }
+
     [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.RemoveUnnecessaryElse)]
     public async Task TestNoDiagnostic_OverlappingLocalVariables()
     {