Fix S2583/S2589 FP: Tuple deconstruction assignment (#8461)

Author: zsolt-kolbay-sonarsource

analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/Extensions/IOperationExtensions.cs

@@ -51,6 +51,9 @@ OperationKindEx.PropertyReference when operation.ToPropertyReference() is { Prop
     internal static IConversionOperationWrapper? AsConversion(this IOperation operation) =>
         operation.As(OperationKindEx.Conversion, IConversionOperationWrapper.FromOperation);
 
+    internal static IDeclarationExpressionOperationWrapper? AsDeclarationExpression(this IOperation operation) =>
+        operation.As(OperationKindEx.DeclarationExpression, IDeclarationExpressionOperationWrapper.FromOperation);
+
     internal static IDeclarationPatternOperationWrapper? AsDeclarationPattern(this IOperation operation) =>
         operation.As(OperationKindEx.DeclarationPattern, IDeclarationPatternOperationWrapper.FromOperation);
 
@@ -69,6 +72,9 @@ OperationKindEx.PropertyReference when operation.ToPropertyReference() is { Prop
     internal static IPropertyReferenceOperationWrapper? AsPropertyReference(this IOperation operation) =>
         operation.As(OperationKindEx.PropertyReference, IPropertyReferenceOperationWrapper.FromOperation);
 
+    internal static ITupleOperationWrapper? AsTuple(this IOperation operation) =>
+        operation.As(OperationKindEx.Tuple, ITupleOperationWrapper.FromOperation);
+
     internal static IAwaitOperationWrapper ToAwait(this IOperation operation) =>
         IAwaitOperationWrapper.FromOperation(operation);
 
@@ -123,6 +129,9 @@ internal static IParameterReferenceOperationWrapper ToParameterReference(this IO
     internal static IEventReferenceOperationWrapper ToEventReference(this IOperation operation) =>
         IEventReferenceOperationWrapper.FromOperation(operation);
 
+    internal static ITupleOperationWrapper ToTuple(this IOperation operation) =>
+        ITupleOperationWrapper.FromOperation(operation);
+
     internal static IUnaryOperationWrapper ToUnary(this IOperation operation) =>
         IUnaryOperationWrapper.FromOperation(operation);
 

analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationDispatcher.cs

@@ -45,6 +45,7 @@ internal static class OperationDispatcher
         { OperationKindEx.CompoundAssignment, new CompoundAssignment() },
         { OperationKindEx.Conversion, new Conversion() },
         { OperationKindEx.DeclarationPattern, new DeclarationPattern() },
+        { OperationKindEx.DeconstructionAssignment, new DeconstructionAssignment() },
         { OperationKindEx.Decrement, new IncrementOrDecrement() },
         { OperationKindEx.DefaultValue, new DefaultValue() },
         { OperationKindEx.DelegateCreation, new NotNullOperation() },

analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/DeconstructionAssignment.cs

@@ -0,0 +1,85 @@
+/*
+ * SonarAnalyzer for .NET
+ * Copyright (C) 2015-2023 SonarSource SA
+ * mailto: contact AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+namespace SonarAnalyzer.SymbolicExecution.Roslyn.OperationProcessors;
+
+internal sealed class DeconstructionAssignment : SimpleProcessor<IDeconstructionAssignmentOperationWrapper>
+{
+    protected override IDeconstructionAssignmentOperationWrapper Convert(IOperation operation) =>
+        IDeconstructionAssignmentOperationWrapper.FromOperation(operation);
+
+    protected override ProgramState Process(SymbolicContext context, IDeconstructionAssignmentOperationWrapper assignment)
+    {
+        var operationValues = TupleElementValues(context.State, assignment.Target, assignment.Value);
+        var newState = context.State;
+        foreach (var (tupleMember, value) in operationValues)
+        {
+            newState = newState.SetOperationAndSymbolValue(tupleMember, value);
+        }
+        return newState;
+    }
+
+    private static IEnumerable<OperationValue> TupleElementValues(ProgramState state, IOperation target, IOperation value)
+    {
+        var operationValues = new List<OperationValue>();
+        var leftTupleElements = TupleElements(Unwrap(target, state).ToTuple(), state);
+        // If the right side is a tuple, then every symbol/constraint is copied to the left side.
+        if (Unwrap(value, state).AsTuple() is { } rightSideTuple)
+        {
+            var rightTupleElements = TupleElements(rightSideTuple, state);
+            for (var i = 0; i < leftTupleElements.Length; i++)
+            {
+                var leftTupleMember = leftTupleElements[i];
+                var rightTupleMember = rightTupleElements[i];
+                if (leftTupleMember.Kind == OperationKindEx.Discard)
+                {
+                    continue;
+                }
+                else if (leftTupleMember.AsTuple() is { } nestedTuple)
+                {
+                    operationValues.AddRange(TupleElementValues(state, nestedTuple.WrappedOperation, rightTupleMember));
+                }
+                else
+                {
+                    operationValues.Add(new(leftTupleMember, state[rightTupleMember]));
+                }
+            }
+        }
+        // If the right side is not a tuple, then every member of the left side tuple is set to empty.
+        else
+        {
+            operationValues.AddRange(leftTupleElements
+                .Where(x => x.Kind != OperationKindEx.Discard)
+                .Select(x => new OperationValue(x, SymbolicValue.Empty)));
+        }
+        return operationValues;
+    }
+
+    private static IOperation[] TupleElements(ITupleOperationWrapper operation, ProgramState state) =>
+        operation.Elements.Select(x => Unwrap(x, state)).ToArray();
+
+    private static IOperation Unwrap(IOperation operation, ProgramState state)
+    {
+        var unwrapped = state.ResolveCaptureAndUnwrapConversion(operation);
+        return unwrapped.AsDeclarationExpression()?.Expression ?? unwrapped;
+    }
+
+    private sealed record OperationValue(IOperation Operation, SymbolicValue Value);
+}

analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/ProgramState.cs

@@ -63,6 +63,16 @@ protected ProgramState(ProgramState original)   // Custom record override constr
         Exceptions = original.Exceptions;
     }
 
+    public ProgramState SetOperationAndSymbolValue(IOperation operation, SymbolicValue value)
+    {
+        var newState = SetOperationValue(operation, value);
+        if (operation.TrackedSymbol(this) is { } symbol)
+        {
+            newState = newState.SetSymbolValue(symbol, value);
+        }
+        return newState;
+    }
+
     public ProgramState SetOperationValue(IOperationWrapper operation, SymbolicValue value) =>
         operation is null
             ? throw new ArgumentNullException(nameof(operation))

analyzers/tests/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/ProgramStateTest.OperationAndSymbolValue.cs

@@ -0,0 +1,58 @@
+/*
+ * SonarAnalyzer for .NET
+ * Copyright (C) 2015-2023 SonarSource SA
+ * mailto: contact AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+using SonarAnalyzer.SymbolicExecution.Roslyn;
+using SonarAnalyzer.UnitTest.TestFramework.SymbolicExecution;
+
+namespace SonarAnalyzer.UnitTest.SymbolicExecution.Roslyn;
+
+public partial class ProgramStateTest
+{
+    [TestMethod]
+    public void SetOperationAndSymbolValue_TrackedSymbol()
+    {
+        var operations = TestHelper.CompileCfgBodyCS("bool b = true;").Blocks[1].Operations;
+        var localReference = operations[0].ChildOperations.First().ToLocalReference();
+        var symbol = localReference.Local;
+        var sut = ProgramState.Empty;
+
+        sut[localReference].Should().BeNull();
+        sut[symbol].Should().BeNull();
+
+        sut = sut.SetOperationAndSymbolValue(localReference.WrappedOperation, SymbolicValue.True);
+
+        sut[localReference].Should().Be(SymbolicValue.True);
+        sut[symbol].Should().Be(SymbolicValue.True);
+    }
+
+    [TestMethod]
+    public void SetOperationAndSymbolValue_NotTrackedSymbol()
+    {
+        var operations = TestHelper.CompileCfgBodyCS("""var texts = new string[] { }; texts[42] = string.Empty;""").Blocks[1].Operations;
+        var arrayElementReference = operations[1].ChildOperations.First().ChildOperations.First().ToArrayElementReference();
+        var sut = ProgramState.Empty;
+
+        sut[arrayElementReference].Should().BeNull();
+
+        sut = sut.SetOperationAndSymbolValue(arrayElementReference.WrappedOperation, SymbolicValue.NotNull);
+
+        sut[arrayElementReference].Should().Be(SymbolicValue.NotNull);
+    }
+}

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/ConditionEvaluatesToConstant.CSharp10.cs

@@ -26,3 +26,35 @@ public static void DoSomething()
         else if (myStruct.y) { } // FN
     }
 }
+
+// https://github.com/SonarSource/sonar-dotnet/issues/7057
+public class Repro_7057
+{
+    private (string, int) SomeTuple() => ("hello", 1);
+    private string SomeString() => "hello";
+
+    public void WithTuple()
+    {
+        string text1 = null;
+        (text1, var (text2, _)) = (SomeString(), SomeTuple());
+        if (text1 == null) // Compliant
+        {
+            Console.WriteLine();
+        }
+        if (text2 == null) // Compliant
+        {
+            Console.WriteLine();
+        }
+
+        string text3 = null;
+        ((text3, _), var (text4, _)) = ((null, 42), ("hello", 42));
+        if (text3 == null)          // Noncompliant
+        {
+            Console.WriteLine();
+        }
+        if (text4 == null)          // Noncompliant
+        {
+            Console.WriteLine();    // Secondary
+        }
+    }
+}

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/ConditionEvaluatesToConstant.CSharp7.cs

@@ -294,7 +294,7 @@ public void GoGoGo()
         {
             var tmp = 0;
             var flag = true;
-            while (flag)            // Noncompliant
+            while (flag)            // Compliant
             {
                 (flag, tmp) = (false, 5);
             }
@@ -329,7 +329,7 @@ public void MutedNull()
         {
             var tmp = 0;
             var flag = "x";
-            while (flag != null)            // Noncompliant
+            while (flag != null)            // Compliant
             {
                 (flag, tmp) = (null, 5);
             }

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/ConditionEvaluatesToConstant.CSharp8.cs

@@ -133,8 +133,8 @@ public void ParenthesizedVariableDesignation_Nested(object arg)
         public void NestedDeconstructionAssignment()
         {
             var (a, (b, _)) = (true, (true, true));
-            if (a) { }  // FN
-            if (b) { }  // FN
+            if (a) { }  // Noncompliant
+            if (b) { }  // Noncompliant
         }
 
         int UsingDeclaration_Null()
@@ -330,7 +330,7 @@ public void AssignmentTarget(bool arg)
             {
             }
 
-            if (b)  // FN
+            if (b)  // Noncompliant
             {
             }
         }

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/ConditionEvaluatesToConstant.CSharp9.cs

@@ -121,11 +121,11 @@ public object InitWithTupleAssignment
             {
                 var tmp = 0;
                 var flag = true;
-                while (flag)        // Noncompliant
+                while (flag)        // Compliant
                 {
                     (flag, tmp) = (false, 5);
                 }
-                o = value;          // Secondary
+                o = value;
             }
         }
     }