SE - Nullable: Copy constraints to Value property (#6841)

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

@@ -71,10 +71,20 @@ internal sealed class PropertyReference : SimpleProcessor<IPropertyReferenceOper
     protected override IPropertyReferenceOperationWrapper Convert(IOperation operation) =>
         IPropertyReferenceOperationWrapper.FromOperation(operation);
 
-    protected override ProgramState Process(SymbolicContext context, IPropertyReferenceOperationWrapper propertyReference) =>
-        propertyReference.Instance.TrackedSymbol() is { } symbol
-            ? context.SetSymbolConstraint(symbol, ObjectConstraint.NotNull)
-            : context.State;
+    protected override ProgramState Process(SymbolicContext context, IPropertyReferenceOperationWrapper propertyReference)
+    {
+        if (propertyReference.Instance.TrackedSymbol() is { } symbol)
+        {
+            var state = context.State.SetSymbolConstraint(symbol, ObjectConstraint.NotNull);
+            return propertyReference.Property.Name == "Value" && propertyReference.Instance.Type.IsNullableValueType() && context.State[symbol] is { } value
+                ? state.SetOperationValue(context.Operation, value)
+                : state;
+        }
+        else
+        {
+            return context.State;
+        }
+    }
 }
 
 internal sealed class ArrayElementReference : SimpleProcessor<IArrayElementReferenceOperationWrapper>

analyzers/tests/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Nullable.cs

@@ -0,0 +1,62 @@
+/*
+ * 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.Constraints;
+using SonarAnalyzer.UnitTest.TestFramework.SymbolicExecution;
+
+namespace SonarAnalyzer.UnitTest.SymbolicExecution.Roslyn;
+
+public partial class RoslynSymbolicExecutionTest
+{
+    [TestMethod]
+    public void Nullable_Assignment_PropagatesConstrainsToValue()
+    {
+        const string code = """
+            bool? value = null;
+            Tag("Null", value);
+            value = true;
+            Tag("True", value);
+            """;
+        var validator = SETestContext.CreateCS(code).Validator;
+        validator.ValidateTag("Null", x => x.HasConstraint(ObjectConstraint.Null).Should().BeTrue());
+        validator.ValidateTag("True", x => x.HasConstraint(BoolConstraint.True).Should().BeTrue());
+    }
+
+    [TestMethod]
+    public void Nullable_Value_ReadsConstraintsFromInstance()
+    {
+        const string code = """
+            var value = arg.Value;
+            Tag("Unknown", value);
+            arg = true;
+            value = arg.Value;
+            Tag("True", value);
+            arg = false;        // This will set additional constraint TestConstraint.First
+            value = arg.Value;
+            Tag("FalseFirst", value);
+            """;
+        var setter = new PreProcessTestCheck(OperationKind.Literal, x => x.Operation.Instance.ConstantValue.Value is false ? x.SetOperationConstraint(TestConstraint.First) : x.State);
+        var validator = SETestContext.CreateCS(code, ", bool? arg", setter).Validator;
+        validator.ValidateTag("Unknown", x => x.Should().BeNull());
+        validator.ValidateTag("True", x => x.HasConstraint(BoolConstraint.True).Should().BeTrue());
+        validator.ValidateTag("FalseFirst", x => x.HasConstraint(BoolConstraint.False).Should().BeTrue());
+        validator.ValidateTag("FalseFirst", x => x.HasConstraint(TestConstraint.First).Should().BeTrue());
+    }
+}