SE - Nullable: Propagate constraints via nullable constructor (#6856)

SonarSource · Mar 31, 2023 · 54f7f60 · 54f7f60
1 parent 7f93aee
commit 54f7f60
Show file tree

Hide file tree

Showing 3 changed files with 45 additions and 6 deletions.
diff --git a/...s/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/ObjectCreation.cs b/...s/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/ObjectCreation.cs
@@ -27,8 +27,26 @@ internal sealed class ObjectCreation : SimpleProcessor<IObjectCreationOperationW
     protected override IObjectCreationOperationWrapper Convert(IOperation operation) =>
         IObjectCreationOperationWrapper.FromOperation(operation);
 
-    protected override ProgramState Process(SymbolicContext context, IObjectCreationOperationWrapper operation) =>
-        operation.Type.IsNullableValueType() && operation.Arguments.IsEmpty
-            ? context.SetOperationConstraint(ObjectConstraint.Null)
-            : context.SetOperationConstraint(ObjectConstraint.NotNull);
+    protected override ProgramState Process(SymbolicContext context, IObjectCreationOperationWrapper operation)
+    {
+        if (operation.Type.IsNullableValueType())
+        {
+            if (operation.Arguments.IsEmpty)
+            {
+                return context.SetOperationConstraint(ObjectConstraint.Null);
+            }
+            else if (context.State[operation.Arguments.First().ToArgument().Value] is { } value)
+            {
+                return context.State.SetOperationValue(context.Operation, value.WithConstraint(ObjectConstraint.NotNull));
+            }
+            else
+            {
+                return context.SetOperationConstraint(ObjectConstraint.NotNull);
+            }
+        }
+        else
+        {
+            return context.SetOperationConstraint(ObjectConstraint.NotNull);
+        }
+    }
 }
diff --git a/analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/SymbolicValue.cs b/analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/SymbolicValue.cs
@@ -41,7 +41,9 @@ public override string ToString() =>
             SerializeConstraints();
 
         public SymbolicValue WithConstraint(SymbolicConstraint constraint) =>
-            this with { Constraints = Constraints.SetItem(constraint.GetType(), constraint) };
+            HasConstraint(constraint)
+                ? this
+                : this with { Constraints = Constraints.SetItem(constraint.GetType(), constraint) };
 
         public SymbolicValue WithoutConstraint(SymbolicConstraint constraint) =>
             HasConstraint(constraint)

diff --git a/...s/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Nullable.cs b/...s/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Nullable.cs
@@ -107,5 +107,24 @@ public void Main<T>() where T: struct
         validator.ValidateTag("TargetTyped", x => x.HasConstraint(ObjectConstraint.NotNull).Should().BeTrue("new() of int produces value 0"));
         validator.ValidateTag("GenericValue", x => x.HasConstraint(ObjectConstraint.NotNull).Should().BeTrue("new() of T produces value T"));
         validator.ValidateTag("GenericNull", x => x.HasConstraint(ObjectConstraint.Null).Should().BeTrue());
-}
+    }
+
+    [TestMethod]
+    public void Nullable_Ctor_Argument_PropagateConstraints()
+    {
+        const string code = """
+            var falseValue = false;     // This will set additional constraint TestConstraint.First
+            bool? isTrue = new Nullable<bool>(true);
+            bool? isFalse = new Nullable<bool>(falseValue);
+            int? isInt = new Nullable<int>(42);
+            Tag("IsTrue", isTrue);
+            Tag("IsFalse", isFalse);
+            Tag("IsInt", isInt);
+            """;
+        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, setter).Validator;
+        validator.ValidateTag("IsTrue", x => x.AllConstraints.Select(x => x.Kind).Should().BeEquivalentTo(new[] { ConstraintKind.ObjectNotNull, ConstraintKind.BoolTrue }));
+        validator.ValidateTag("IsFalse", x => x.AllConstraints.Select(x => x.Kind).Should().BeEquivalentTo(new[] { ConstraintKind.ObjectNotNull, ConstraintKind.BoolFalse, (ConstraintKind)ConstraintKindTest.First }));
+        validator.ValidateTag("IsInt", x => x.AllConstraints.Select(x => x.Kind).Should().BeEquivalentTo(new[] { ConstraintKind.ObjectNotNull }));
+    }
 }