Ignore attributes when single or named argument

analyzers/src/SonarAnalyzer.CSharp/Rules/MagicNumberShouldNotBeUsed.cs

@@ -70,12 +70,20 @@ private static bool IsExceptionToTheRule(LiteralExpressionSyntax literalExpressi
             || literalExpression.FirstAncestorOrSelf<PragmaWarningDirectiveTriviaSyntax>() != null
             // It's ok to use magic numbers in property declaration
             || IsInsideProperty(literalExpression)
-            || IsNamedArgument(literalExpression);
+            || IsNamedArgument(literalExpression)
+            || IsInAllowedAttribute(literalExpression);
 
         private static bool IsNamedArgument(LiteralExpressionSyntax literalExpression) =>
             literalExpression.Parent is ArgumentSyntax arg
             && arg.NameColon is not null;
 
+        // Either it is the only argument of the attribute, or it is a named argument.
+        private static bool IsInAllowedAttribute(LiteralExpressionSyntax literalExpression) =>
+            literalExpression.Parent is AttributeArgumentSyntax arg
+            && (arg.NameColon is not null
+                || arg.NameEquals is not null
+                || (arg.Parent is AttributeArgumentListSyntax argList && argList.Arguments.Count == 1));
+
         // Inside property we consider magic numbers as exceptions in the following cases:
         //   - A {get; set;} = MAGIC_NUMBER
         //   - A { get { return MAGIC_NUMBER; } }

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/MagicNumberShouldNotBeUsed.cs

@@ -65,14 +65,13 @@ public override int GetHashCode()
             return MY_VALUE * 397;
         }
 
-        [Foo(Bar: 42, Baz = 43)] // Noncompliant FP - Compliant, explicit attribute argument names
-        // Noncompliant @-1
+        [Foo(Bar: 42, Baz = 43)] // Compliant, explicit attribute argument names
         public void Foo(int value = 42)
         {
             var x = -1 < 1;
         }
 
-        [Foo(42)] // Noncompliant FP -Compliant, attribute with only one argument
+        [Foo(42)] // Compliant, attribute with only one argument
         public static int Bar(int value) => 0;
     }