Fix RCS1211

ChangeLog.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix [RCS1216](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1216.md) ([#1094](https://github.com/JosefPihrt/Roslynator/pull/1094)).
 - Fix [RCS1146](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1146.md) ([#1098](https://github.com/JosefPihrt/Roslynator/pull/1098)).
 - Fix [RCS1154](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1154.md) ([#1105](https://github.com/JosefPihrt/Roslynator/pull/1105)).
+- Fix [RCS1211](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1211.md) ([#1095](https://github.com/JosefPihrt/Roslynator/pull/1095)).
 
 ## [4.3.0] - 2023-04-24
 

src/Analyzers/CSharp/Analysis/RemoveUnnecessaryBracesInSwitchSectionAnalyzer.cs

@@ -93,7 +93,7 @@ public static void AnalyzerSwitchSection(SyntaxNodeAnalysisContext context)
 
         // If any of the other case blocks contain a definition for the same local variables then removing the braces would introduce a new error.
         if (switchSection.Parent is SwitchStatementSyntax switchStatement
-            && LocallyDeclaredVariablesOverlapWithAnyOtherSwitchSections(switchStatement, block, context.SemanticModel))
+            && SwitchLocallyDeclaredVariablesHelper.BlockDeclaredVariablesOverlapWithOtherSwitchSections(block, switchStatement, context.SemanticModel))
         {
             return;
         }
@@ -107,42 +107,4 @@ static bool AnalyzeTrivia(SyntaxTriviaList trivia)
         }
     }
 
-    private static bool LocallyDeclaredVariablesOverlapWithAnyOtherSwitchSections(SwitchStatementSyntax switchStatement, BlockSyntax switchBlock, SemanticModel semanticModel)
-    {
-        ImmutableArray<ISymbol> sectionVariablesDeclared = semanticModel.AnalyzeDataFlow(switchBlock)!
-            .VariablesDeclared;
-
-        if (sectionVariablesDeclared.IsEmpty)
-            return false;
-
-        ImmutableHashSet<string> sectionDeclaredVariablesNames = sectionVariablesDeclared
-            .Select(s => s.Name)
-            .ToImmutableHashSet();
-
-        foreach (SwitchSectionSyntax otherSection in switchStatement.Sections)
-        {
-            if (otherSection.Span.Contains(switchBlock.Span))
-                continue;
-
-            foreach (SwitchLabelSyntax label in otherSection.Labels)
-            {
-                if (label is not CasePatternSwitchLabelSyntax casePatternSwitchLabel)
-                    continue;
-
-                if (PatternMatchingVariableDeclarationHelper.AnyDeclaredVariablesMatch(casePatternSwitchLabel.Pattern, sectionDeclaredVariablesNames))
-                    return true;
-            }
-
-            foreach (StatementSyntax statement in otherSection.Statements)
-            {
-                foreach (ISymbol symbol in semanticModel.AnalyzeDataFlow(statement)!.VariablesDeclared)
-                {
-                    if (sectionDeclaredVariablesNames.Contains(symbol.Name))
-                        return true;
-                }
-            }
-        }
-
-        return false;
-    }
 }

src/Analyzers/CSharp/Analysis/RemoveUnnecessaryElseAnalyzer.cs

@@ -61,8 +61,17 @@ 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 && LocalDeclaredVariablesOverlap(elseBlock, ifBlock, semanticModel))
-            return false;
+        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();
 

src/Analyzers/CSharp/Analysis/SwitchLocallyDeclaredVariablesHelper.cs

@@ -0,0 +1,48 @@
+using System.Collections.Immutable;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Roslynator.CSharp.Analysis;
+
+internal static class SwitchLocallyDeclaredVariablesHelper
+{
+    internal static bool BlockDeclaredVariablesOverlapWithOtherSwitchSections(BlockSyntax block, SwitchStatementSyntax switchStatement, SemanticModel semanticModel)
+    {
+        ImmutableArray<ISymbol> sectionVariablesDeclared = semanticModel.AnalyzeDataFlow(block)!
+            .VariablesDeclared;
+
+        if (sectionVariablesDeclared.IsEmpty)
+            return false;
+
+        ImmutableHashSet<string> sectionDeclaredVariablesNames = sectionVariablesDeclared
+            .Select(s => s.Name)
+            .ToImmutableHashSet();
+
+        foreach (SwitchSectionSyntax otherSection in switchStatement.Sections)
+        {
+            if (otherSection.Span.Contains(block.Span))
+                continue;
+
+            foreach (SwitchLabelSyntax label in otherSection.Labels)
+            {
+                if (label is not CasePatternSwitchLabelSyntax casePatternSwitchLabel)
+                    continue;
+
+                if (PatternMatchingVariableDeclarationHelper.AnyDeclaredVariablesMatch(casePatternSwitchLabel.Pattern, sectionDeclaredVariablesNames))
+                    return true;
+            }
+
+            foreach (StatementSyntax statement in otherSection.Statements)
+            {
+                foreach (ISymbol symbol in semanticModel.AnalyzeDataFlow(statement)!.VariablesDeclared)
+                {
+                    if (sectionDeclaredVariablesNames.Contains(symbol.Name))
+                        return true;
+                }
+            }
+        }
+
+        return false;
+    }
+}

src/Tests/Analyzers.Tests/RCS1211RemoveUnnecessaryElseTests.cs

@@ -66,6 +66,41 @@ int M(bool flag)
         }
     }
 }
+");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.RemoveUnnecessaryElse)]
+    public async Task TestNoDiagnostic_OverlappingLocalVariablesWithSwitch()
+    {
+        await VerifyNoDiagnosticAsync(@"
+class C
+{
+    int M(int i, bool flag)
+    {
+        switch(i)
+        {
+            case 0:
+                if(flag)
+                {
+                    var z = 1;
+                    return z;
+                }   
+                break;
+            case 1:
+                if(flag)
+                {
+                    var y = 1;
+                    return y;
+                }
+                else
+                {
+                    var z = 1;
+                    return z;
+                }
+        }
+        return 2;
+    }
+}
 ");
     }
 }