Filtered out log calls with invalid template parameter names

Author: Sviatoslav Bychkov

docs/ADR/ADR-06_Skip_log_calls_with_invalid_template_parameter_names.md

@@ -0,0 +1,29 @@
+### Title: ADR-06 Skip log calls with invalid template parameter names
+### Status: Accepted
+### Context:
+
+Template message parameters are parsed to generate logging code dynamically.
+The template parameters' names are critical for synchronizing the log message format with the corresponding parameters in the code.
+If a parameter name is invalid, the generated code may produce unexpected results or fail to align with the user's intended behavior.
+
+### Decision:
+
+I will not process log calls if the template message parameters contain invalid names.
+Instead, I will filter these calls and report a diagnostic warning indicating the invalid parameter name.
+
+### Consequences:
+
+* **Positive**:
+  * Users will be notified of issues in their template messages.
+  * The generator remains simple and reliable, reducing potential bugs and unexpected behavior.
+
+* **Negative**:
+  * Users must fix their invalid parameter names before the log calls are processed. This might require additional effort upfront but is offset by the long-term benefits of correctness.
+
+### Alternatives Considered
+
+Automatically rename invalid parameter names to conform to a valid format (e.g., replacing spaces with underscores).
+
+**Rejected Because**:
+* It introduces unexpected behavior for the user.
+* It adds some complexity to the generator and increases the risk of synchronization (template parameters <-> template message) errors.

src/AutoLoggerMessageGenerator.UnitTests/Utilities/IdentifierHelperTests.cs

@@ -10,7 +10,7 @@ public class IdentifierHelperTests
     [InlineData("_Valid__Name___", "_Valid__Name___")]
     [InlineData("🔥Invalid🔥Emoji🔥", "__Invalid__Emoji__")]
     [InlineData("123Name", "_123Name")]
-    [InlineData("Name#With$Special%Chars", "Name_With_Special_Chars")] 
+    [InlineData("Name#With$Special%Chars", "Name_With_Special_Chars")]
     public void ToValidCSharpMethodName_ShouldSanitizeCorrectly(string input, string expected)
     {
         var result = IdentifierHelper.ToValidCSharpMethodName(input);
@@ -25,4 +25,23 @@ public void ToValidCSharpMethodName_ShouldThrow_WhenInputIsNull(string? input)
         var action = () => IdentifierHelper.ToValidCSharpMethodName(input);
         action.Should().ThrowExactly<ArgumentNullException>();
     }
+
+    [Theory]
+    [InlineData("validName", true)]
+    [InlineData("_validName", true)]
+    [InlineData("ValidName123", true)]
+    [InlineData("a", true)]
+    [InlineData("invalid name", false)]
+    [InlineData("123Invalid", false)]
+    [InlineData("invalid-name", false)]
+    [InlineData("e.invalid", false)]
+    [InlineData("i🔥nvalid", false)]
+    [InlineData("", false)]
+    [InlineData(null, false)]
+    public void IsValidCSharpParameterName_WithGivenParameterName_ShouldReturnTheGivenResult(string parameterName,
+        bool isValid)
+    {
+        var result = IdentifierHelper.IsValidCSharpParameterName(parameterName);
+        result.Should().Be(isValid);
+    }
 }

src/AutoLoggerMessageGenerator/Extractors/LogCallParametersExtractor.cs

@@ -19,6 +19,10 @@ internal partial class LogCallParametersExtractor(LogPropertiesCheck? logPropert
             .Select(TransformParameterName)
             .ToArray();
 
+        // TODO: Report a diagnostic message in the separate analyzer that some parameter names are "invalid"
+        if (!templateParametersNames.All(IdentifierHelper.IsValidCSharpParameterName))
+            return null;
+
         var argumentParameterPrefix = ParameterName.TrimStart('@');
         var methodParameters = methodSymbol.Parameters
             .Where(c => c.Name.StartsWith(argumentParameterPrefix))

src/AutoLoggerMessageGenerator/Utilities/IdentifierHelper.cs

@@ -3,7 +3,7 @@
 
 namespace AutoLoggerMessageGenerator.Utilities;
 
-internal static class IdentifierHelper
+internal static partial class IdentifierHelper
 {
     public static string ToValidCSharpMethodName(string? input)
     {
@@ -16,4 +16,10 @@ public static string ToValidCSharpMethodName(string? input)
 
         return sanitizedInput;
     }
+
+    public static bool IsValidCSharpParameterName(string name) =>
+        !string.IsNullOrEmpty(name) && IsValidCSharpParameterNameRegex().IsMatch(name);
+
+    [GeneratedRegex(@"^@?[a-zA-Z_][a-zA-Z0-9_]*$")]
+    private static partial Regex IsValidCSharpParameterNameRegex();
 }