Add support for indexer access

SonarSource · Feb 7, 2023 · 7257579 · 7257579
1 parent 38a68cb
commit 7257579
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Showing 4 changed files with 19 additions and 4 deletions.
diff --git a/analyzers/src/SonarAnalyzer.CSharp/Rules/UnusedStringBuilder.cs b/analyzers/src/SonarAnalyzer.CSharp/Rules/UnusedStringBuilder.cs
@@ -60,6 +60,9 @@ public sealed class UnusedStringBuilder : UnusedStringBuilderBase<SyntaxKind, Va
     protected override bool IsWithinInterpolatedString(IList<InterpolationSyntax> interpolations, ISymbol variableSymbol, SemanticModel semanticModel) =>
         interpolations.Any(x => IsSameVariable(x.Expression, variableSymbol, semanticModel));
 
+    protected override bool IsPropertyReferenced(VariableDeclaratorSyntax declaration, IList<InvocationExpressionSyntax> invocations, ISymbol variableSymbol, SemanticModel semanticModel) =>
+        GetElementAccessExpressions(declaration).Any(x => IsSameVariable(x.Expression, variableSymbol, semanticModel));
+
     private static bool IsStringBuilderObjectCreation(ExpressionSyntax expression, SemanticModel semanticModel) =>
         (expression is ObjectCreationExpressionSyntax || ImplicitObjectCreationExpressionSyntaxWrapper.IsInstance(expression))
         && ObjectCreationFactory.Create(expression).IsKnownType(KnownType.System_Text_StringBuilder, semanticModel);
@@ -72,6 +75,11 @@ public sealed class UnusedStringBuilder : UnusedStringBuilderBase<SyntaxKind, Va
     private static bool IsSameVariable(IdentifierNameSyntax identifier, ISymbol variableSymbol, SemanticModel semanticModel) =>
         variableSymbol.Equals(semanticModel.GetSymbolInfo(identifier).Symbol);
 
+    private static IList<ElementAccessExpressionSyntax> GetElementAccessExpressions(VariableDeclaratorSyntax declaration) =>
+        declaration.IsTopLevel()
+        ? GetTopLevelStatementSyntax<ElementAccessExpressionSyntax>(declaration)
+        : declaration.Parent.Parent.Parent.DescendantNodes().OfType<ElementAccessExpressionSyntax>().ToList();
+
     private static IList<T> GetTopLevelStatementSyntax<T>(VariableDeclaratorSyntax declaration)
     {
         List<T> list = new();

diff --git a/analyzers/src/SonarAnalyzer.Common/Rules/UnusedStringBuilderBase.cs b/analyzers/src/SonarAnalyzer.Common/Rules/UnusedStringBuilderBase.cs
@@ -41,6 +41,7 @@ public abstract class UnusedStringBuilderBase<TSyntaxKind, TVariableDeclarator,
     protected abstract bool IsPassedToMethod(IList<TInvocationExpression> invocations, ISymbol variableSymbol, SemanticModel semanticModel);
     protected abstract bool IsReturned(IList<TReturnStatement> returnStatements, ISymbol variableSymbol, SemanticModel semanticModel);
     protected abstract bool IsWithinInterpolatedString(IList<TInterpolatedString> interpolations, ISymbol variableSymbol, SemanticModel semanticModel);
+    protected abstract bool IsPropertyReferenced(TVariableDeclarator declaration, IList<TInvocationExpression> invocations, ISymbol variableSymbol, SemanticModel semanticModel);
 
     protected UnusedStringBuilderBase() : base(DiagnosticId) { }
 
@@ -57,7 +58,8 @@ public abstract class UnusedStringBuilderBase<TSyntaxKind, TVariableDeclarator,
             if (IsStringBuilderContentRead(invocations, variableSymbol, c.SemanticModel)
                 || IsPassedToMethod(invocations, variableSymbol, c.SemanticModel)
                 || IsReturned(GetReturnStatements(variableDeclaration), variableSymbol, c.SemanticModel)
-                || IsWithinInterpolatedString(GetInterpolatedStrings(variableDeclaration), variableSymbol, c.SemanticModel))
+                || IsWithinInterpolatedString(GetInterpolatedStrings(variableDeclaration), variableSymbol, c.SemanticModel)
+                || IsPropertyReferenced(variableDeclaration, invocations, variableSymbol, c.SemanticModel))
             {
                 return;
             }

diff --git a/analyzers/src/SonarAnalyzer.VisualBasic/Rules/UnusedStringBuilder.cs b/analyzers/src/SonarAnalyzer.VisualBasic/Rules/UnusedStringBuilder.cs
@@ -18,6 +18,8 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+using StyleCop.Analyzers.Lightup;
+
 namespace SonarAnalyzer.Rules.VisualBasic;
 
 [DiagnosticAnalyzer(LanguageNames.VisualBasic)]
@@ -54,6 +56,9 @@ public sealed class UnusedStringBuilder : UnusedStringBuilderBase<SyntaxKind, Va
     protected override bool IsWithinInterpolatedString(IList<InterpolationSyntax> interpolations, ISymbol variableSymbol, SemanticModel semanticModel) =>
         interpolations.Any(x => IsSameVariable(x.Expression, variableSymbol, semanticModel));
 
+    protected override bool IsPropertyReferenced(VariableDeclaratorSyntax declaration, IList<InvocationExpressionSyntax> invocations, ISymbol variableSymbol, SemanticModel semanticModel) =>
+        invocations.Any(x => IsSameVariable(x.Expression, variableSymbol, semanticModel) && semanticModel.GetOperation(x).Kind is OperationKindEx.PropertyReference);
+
     private static bool IsSameVariable(ExpressionSyntax expression, ISymbol variableSymbol, SemanticModel semanticModel) =>
         expression.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().Any(p => IsSameVariable(p, variableSymbol, semanticModel))
         || (expression.Ancestors().OfType<ConditionalAccessExpressionSyntax>().Any() && expression.Ancestors().OfType<ConditionalAccessExpressionSyntax>().First()

diff --git a/analyzers/tests/SonarAnalyzer.UnitTest/Rules/UnusedStringBuilderTest.cs b/analyzers/tests/SonarAnalyzer.UnitTest/Rules/UnusedStringBuilderTest.cs
@@ -39,7 +39,7 @@ public class UnusedStringBuilderTest
     [DataRow("""var a = sb.Append("").Append("").Append("").Append("").ToString().ToLower();""", true)]
     [DataRow("sb.CopyTo(0, new char[1], 0, 1);", true)]
     [DataRow("sb.GetChunks();", true)]
-    [DataRow("var a = sb[0];", false)] // FP
+    [DataRow("var a = sb[0];", true)]
     [DataRow("""sb?.Append("").ToString().ToLower();""", true)]
     [DataRow("""@sb.Append("").ToString();""", true)]
     [DataRow("sb.Remove(sb.Length - 1, 1);", true)]
@@ -83,7 +83,7 @@ public void MyMethod()
     [DataRow("""var a = sb.Append("").Append("").Append("").Append("").ToString().ToLower();""", true)]
     [DataRow("sb.CopyTo(0, new char[1], 0, 1);", true)]
     [DataRow("sb.GetChunks();", true)]
-    [DataRow("var a = sb[0];", false)] // FP
+    [DataRow("var a = sb[0];", true)]
     [DataRow("""sb?.Append("").ToString().ToLower();""", true)]
     [DataRow("""@sb.Append("").ToString();""", true)]
     [DataRow("sb.Remove(sb.Length - 1, 1);", true)]
@@ -115,7 +115,7 @@ public void UnusedStringBuilder_TopLevelStatements(string expression, bool compl
     [DataRow("""Dim a = sb.Append("").Append("").Append("").Append("").ToString().ToLower()""", true)]
     [DataRow("sb.CopyTo(0, New Char(0) {}, 0, 1)", true)]
     [DataRow("sb.GetChunks()", true)]
-    [DataRow("Dim a = sb(0)", false)] // FP
+    [DataRow("Dim a = sb(0)", true)]
     [DataRow("""sb?.Append("").ToString().ToLower()""", true)]
     [DataRow("""sb.Append("").ToString()""", true)]
     [DataRow("sb.Remove(sb.Length - 1, 1)", true)]