CompileTimeLogger

A Roslyn analyzer that detects ILogger.Log* method calls and provides code fixes to convert them to compile-time generated logging using the [LoggerMessage] attribute for better performance.

Why Use Compile-Time Logging?

The [LoggerMessage] attribute (introduced in .NET 6) enables source generation for high-performance logging:

• Zero allocations - No boxing of value types
• No parsing at runtime - Message templates are parsed at compile time
• Strongly typed - Compile-time validation of log message parameters
• Better performance - Up to 6x faster than traditional logging extensions

Installation

dotnet add package CompileTimeLogger

Or via Package Manager:

Install-Package CompileTimeLogger

Usage

The analyzer detects calls like:

_logger.LogInformation("User {UserId} logged in", userId);

And offers two code fixes:

Fix 1: Convert to Instance Method

// Before
_logger.LogInformation("User {UserId} logged in", userId);

// After
LogUserLoggedIn(userId);

[LoggerMessage(Level = LogLevel.Information, Message = "User {UserId} logged in")]
private partial void LogUserLoggedIn(string userId);

Fix 2: Convert to Private Log Class

// Before
_logger.LogInformation("User {UserId} logged in", userId);

// After
Log.UserLoggedIn(_logger, userId);

private static partial class Log
{
    [LoggerMessage(Level = LogLevel.Information, Message = "User {UserId} logged in")]
    public static partial void UserLoggedIn(ILogger logger, string userId);
}

Supported Log Methods

• LogTrace
• LogDebug
• LogInformation
• LogWarning
• LogError
• LogCritical

Features

• Works with both ILogger and ILogger<T>
• Handles exceptions in log calls (e.g., _logger.LogError(ex, "message"))
• Automatically extracts message template placeholders
• Generates properly named methods from message templates
• Makes containing class partial automatically

Requirements

• .NET 6.0 or later (for [LoggerMessage] attribute support)
• C# 9.0 or later

Diagnostic ID

ID	Description
CTL001	ILogger.Log* call can be converted to compile-time generated logging

License

MIT License - see LICENSE.txt