Logging source generator: support generic methods (lift SYSLIB1011)

docs/project/list-of-diagnostics.md

@@ -137,7 +137,7 @@ The diagnostic id values reserved for .NET Libraries analyzer warnings are `SYSL
 |  __`SYSLIB1008`__ | One of the arguments to a logging method must implement the Microsoft.Extensions.Logging.ILogger interface |
 |  __`SYSLIB1009`__ | Logging methods must be static |
 |  __`SYSLIB1010`__ | Logging methods must be partial |
-|  __`SYSLIB1011`__ | Logging methods cannot be generic |
+|  __`SYSLIB1011`__ | Logging methods cannot use the `allows ref struct` constraint |
 |  __`SYSLIB1012`__ | Redundant qualifier in logging message |
 |  __`SYSLIB1013`__ | Don't include exception parameters as templates in the logging message |
 |  __`SYSLIB1014`__ | Logging template has no corresponding method argument |

src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/DiagnosticDescriptors.cs

@@ -81,10 +81,10 @@ public static class DiagnosticDescriptors
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);
 
-        public static DiagnosticDescriptor LoggingMethodIsGeneric { get; } = DiagnosticDescriptorHelper.Create(
+        public static DiagnosticDescriptor LoggingMethodHasAllowsRefStructConstraint { get; } = DiagnosticDescriptorHelper.Create(
             id: "SYSLIB1011",
-            title: new LocalizableResourceString(nameof(SR.LoggingMethodIsGenericMessage), SR.ResourceManager, typeof(FxResources.Microsoft.Extensions.Logging.Generators.SR)),
-            messageFormat: new LocalizableResourceString(nameof(SR.LoggingMethodIsGenericMessage), SR.ResourceManager, typeof(FxResources.Microsoft.Extensions.Logging.Generators.SR)),
+            title: new LocalizableResourceString(nameof(SR.LoggingMethodHasAllowsRefStructConstraintMessage), SR.ResourceManager, typeof(FxResources.Microsoft.Extensions.Logging.Generators.SR)),
+            messageFormat: new LocalizableResourceString(nameof(SR.LoggingMethodHasAllowsRefStructConstraintMessage), SR.ResourceManager, typeof(FxResources.Microsoft.Extensions.Logging.Generators.SR)),
             category: "LoggingGenerator",
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);

src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Emitter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Text;
 using System.Threading;
 using Microsoft.CodeAnalysis;
@@ -60,6 +59,7 @@ public string Emit(IReadOnlyList<LoggerClass> logClasses, CancellationToken canc
             private static bool UseLoggerMessageDefine(LoggerMethod lm)
             {
                 bool result =
+                    (lm.TypeParameters.Count == 0) &&                                   // generic methods can't use LoggerMessage.Define's static callback
                     (lm.TemplateParameters.Count <= MaxLoggerMessageDefineArguments) && // more args than LoggerMessage.Define can handle
                     (lm.Level != null) &&                                               // dynamic log level, which LoggerMessage.Define can't handle
                     (lm.TemplateList.Count == lm.TemplateParameters.Count);             // mismatch in template to args, which LoggerMessage.Define can't handle
@@ -146,11 +146,15 @@ namespace {lc.Namespace}
 
             private void GenStruct(LoggerMethod lm, string nestedIndentation)
             {
-                _builder.AppendLine($@"
+                _builder.Append($@"
         {nestedIndentation}/// {GeneratedTypeSummary}
         {nestedIndentation}[{s_generatedCodeAttribute}]
         {nestedIndentation}[{EditorBrowsableAttribute}]
-        {nestedIndentation}private readonly struct __{lm.UniqueName}Struct : global::System.Collections.Generic.IReadOnlyList<global::System.Collections.Generic.KeyValuePair<string, object?>>
+        {nestedIndentation}private readonly struct __{lm.UniqueName}Struct");
+                GenTypeParameterList(lm);
+                _builder.Append($" : global::System.Collections.Generic.IReadOnlyList<global::System.Collections.Generic.KeyValuePair<string, object?>>");
+                GenTypeConstraints(lm, nestedIndentation + "    ");
+                _builder.AppendLine($@"
         {nestedIndentation}{{");
                 GenFields(lm, nestedIndentation);
 
@@ -175,7 +179,7 @@ private void GenStruct(LoggerMethod lm, string nestedIndentation)
                 GenVariableAssignments(lm, nestedIndentation);
 
                 string formatMethodBegin =
-                    !lm.Message.Contains('{') ? "" :
+                    lm.Message.IndexOf('{') < 0 ? "" :
                     _hasStringCreate ? "string.Create(global::System.Globalization.CultureInfo.InvariantCulture, " :
                     "global::System.FormattableString.Invariant(";
                 string formatMethodEnd = formatMethodBegin.Length > 0 ? ")" : "";
@@ -185,7 +189,9 @@ private void GenStruct(LoggerMethod lm, string nestedIndentation)
             {nestedIndentation}}}
 ");
                 _builder.Append($@"
-            {nestedIndentation}public static readonly global::System.Func<__{lm.UniqueName}Struct, global::System.Exception?, string> Format = (state, ex) => state.ToString();
+            {nestedIndentation}public static readonly global::System.Func<__{lm.UniqueName}Struct");
+                GenTypeParameterList(lm);
+                _builder.Append($@", global::System.Exception?, string> Format = (state, ex) => state.ToString();
 
             {nestedIndentation}public int Count => {lm.TemplateParameters.Count + 1};
 
@@ -369,9 +375,9 @@ private void GenArguments(LoggerMethod lm)
 
             private void GenHolder(LoggerMethod lm)
             {
-                string typeName = $"__{lm.UniqueName}Struct";
-
-                _builder.Append($"new {typeName}(");
+                _builder.Append($"new __{lm.UniqueName}Struct");
+                GenTypeParameterList(lm);
+                _builder.Append('(');
                 foreach (LoggerParameter p in lm.TemplateParameters)
                 {
                     if (p != lm.TemplateParameters[0])
@@ -385,6 +391,44 @@ private void GenHolder(LoggerMethod lm)
                 _builder.Append(')');
             }
 
+            private void GenTypeParameterList(LoggerMethod lm)
+            {
+                if (lm.TypeParameters.Count == 0)
+                {
+                    return;
+                }
+
+                _builder.Append('<');
+                bool firstItem = true;
+                foreach (LoggerMethodTypeParameter tp in lm.TypeParameters)
+                {
+                    if (firstItem)
+                    {
+                        firstItem = false;
+                    }
+                    else
+                    {
+                        _builder.Append(", ");
+                    }
+
+                    _builder.Append(tp.Name);
+                }
+
+                _builder.Append('>');
+            }
+
+            private void GenTypeConstraints(LoggerMethod lm, string nestedIndentation)
+            {
+                foreach (LoggerMethodTypeParameter tp in lm.TypeParameters)
+                {
+                    if (tp.Constraints is not null)
+                    {
+                        _builder.Append(@$"
+            {nestedIndentation}where {tp.Name} : {tp.Constraints}");
+                    }
+                }
+            }
+
             private void GenLogMethod(LoggerMethod lm, string nestedIndentation)
             {
                 string level = GetLogLevel(lm);
@@ -414,11 +458,15 @@ private void GenLogMethod(LoggerMethod lm, string nestedIndentation)
 
                 _builder.Append($@"
         {nestedIndentation}[{s_generatedCodeAttribute}]
-        {nestedIndentation}{lm.Modifiers} void {lm.Name}({extension}");
+        {nestedIndentation}{lm.Modifiers} void {lm.Name}");
+                GenTypeParameterList(lm);
+                _builder.Append($"({extension}");
 
                 GenParameters(lm);
 
-                _builder.Append($@")
+                _builder.Append(')');
+                GenTypeConstraints(lm, nestedIndentation);
+                _builder.Append($@"
         {nestedIndentation}{{");
 
                 string enabledCheckIndentation = lm.SkipEnabledCheck ? "" : "    ";
@@ -448,7 +496,9 @@ private void GenLogMethod(LoggerMethod lm, string nestedIndentation)
                 GenHolder(lm);
                 _builder.Append($@",
                 {nestedIndentation}{enabledCheckIndentation}{exceptionArg},
-                {nestedIndentation}{enabledCheckIndentation}__{lm.UniqueName}Struct.Format);");
+                {nestedIndentation}{enabledCheckIndentation}__{lm.UniqueName}Struct");
+                GenTypeParameterList(lm);
+                _builder.Append(".Format);");
                 }
 
                 if (!lm.SkipEnabledCheck)

src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Parser.cs

@@ -22,6 +22,13 @@ internal sealed class Parser
         {
             internal const string LoggerMessageAttribute = "Microsoft.Extensions.Logging.LoggerMessageAttribute";
 
+            // ITypeParameterSymbol.AllowsRefLikeType was added in Roslyn 4.9 (C# 13). Access via a compiled
+            // delegate so the same source file compiles against all supported Roslyn versions, while
+            // avoiding the per-call overhead of PropertyInfo.GetValue boxing.
+            private static readonly Func<ITypeParameterSymbol, bool>? s_getAllowsRefLikeType =
+                (Func<ITypeParameterSymbol, bool>?)
+                    typeof(ITypeParameterSymbol).GetProperty("AllowsRefLikeType")?.GetGetMethod()!.CreateDelegate(typeof(Func<ITypeParameterSymbol, bool>));
+
             private readonly CancellationToken _cancellationToken;
             private readonly INamedTypeSymbol _loggerMessageAttribute;
             private readonly INamedTypeSymbol _loggerSymbol;
@@ -239,8 +246,29 @@ public IReadOnlyList<LoggerClass> GetLogClasses(IEnumerable<ClassDeclarationSynt
                                         SkipEnabledCheck = skipEnabledCheck
                                     };
 
+                                    foreach (ITypeParameterSymbol tp in logMethodSymbol.TypeParameters)
+                                    {
+                                        lm.TypeParameters.Add(new LoggerMethodTypeParameter
+                                        {
+                                            Name = tp.Name,
+                                            Constraints = GetTypeParameterConstraints(tp)
+                                        });
+                                    }
+
                                     bool keepMethod = true;   // whether or not we want to keep the method definition or if it's got errors making it so we should discard it instead
 
+                                    // Forbid 'allows ref struct': the code generator stores template parameters as
+                                    // fields in a generated struct, so ref-struct type arguments cannot be supported.
+                                    foreach (ITypeParameterSymbol tp in logMethodSymbol.TypeParameters)
+                                    {
+                                        if (s_getAllowsRefLikeType?.Invoke(tp) == true)
+                                        {
+                                            Diag(DiagnosticDescriptors.LoggingMethodHasAllowsRefStructConstraint, method.Identifier.GetLocation());
+                                            keepMethod = false;
+                                            break;
+                                        }
+                                    }
+
                                     bool success = ExtractTemplates(message, lm.TemplateMap, lm.TemplateList);
                                     if (!success)
                                     {
@@ -263,13 +291,6 @@ public IReadOnlyList<LoggerClass> GetLogClasses(IEnumerable<ClassDeclarationSynt
                                         keepMethod = false;
                                     }
 
-                                    if (method.Arity > 0)
-                                    {
-                                        // we don't currently support generic methods
-                                        Diag(DiagnosticDescriptors.LoggingMethodIsGeneric, method.Identifier.GetLocation());
-                                        keepMethod = false;
-                                    }
-
                                     bool isStatic = false;
                                     bool isPartial = false;
                                     foreach (SyntaxToken mod in method.Modifiers)
@@ -369,6 +390,7 @@ public IReadOnlyList<LoggerClass> GetLogClasses(IEnumerable<ClassDeclarationSynt
 
                                         string typeName = paramTypeSymbol.ToDisplayString(
                                             SymbolDisplayFormat.FullyQualifiedFormat.WithMiscellaneousOptions(
+                                                SymbolDisplayFormat.FullyQualifiedFormat.MiscellaneousOptions |
                                                 SymbolDisplayMiscellaneousOptions.IncludeNullableReferenceTypeModifier));
 
                                         var lp = new LoggerParameter
@@ -714,6 +736,48 @@ private static string GenerateClassName(TypeDeclarationSyntax typeDeclaration)
                 return (loggerField, false);
             }
 
+            private static string? GetTypeParameterConstraints(ITypeParameterSymbol typeParameter)
+            {
+                var constraints = new List<string>();
+
+                if (typeParameter.HasReferenceTypeConstraint)
+                {
+                    string classConstraint = typeParameter.ReferenceTypeConstraintNullableAnnotation == NullableAnnotation.Annotated
+                        ? "class?"
+                        : "class";
+                    constraints.Add(classConstraint);
+                }
+                else if (typeParameter.HasValueTypeConstraint)
+                {
+                    // HasUnmanagedTypeConstraint also implies HasValueTypeConstraint
+                    constraints.Add(typeParameter.HasUnmanagedTypeConstraint ? "unmanaged" : "struct");
+                }
+                else if (typeParameter.HasNotNullConstraint)
+                {
+                    constraints.Add("notnull");
+                }
+
+                foreach (ITypeSymbol constraintType in typeParameter.ConstraintTypes)
+                {
+                    if (constraintType is IErrorTypeSymbol)
+                    {
+                        continue;
+                    }
+
+                    constraints.Add(constraintType.ToDisplayString(
+                        SymbolDisplayFormat.FullyQualifiedFormat.WithMiscellaneousOptions(
+                            SymbolDisplayFormat.FullyQualifiedFormat.MiscellaneousOptions |
+                            SymbolDisplayMiscellaneousOptions.IncludeNullableReferenceTypeModifier)));
+                }
+
+                if (typeParameter.HasConstructorConstraint)
+                {
+                    constraints.Add("new()");
+                }
+
+                return constraints.Count > 0 ? string.Join(", ", constraints) : null;
+            }
+
             private void Diag(DiagnosticDescriptor desc, Location? location, params object?[]? messageArgs)
             {
                 // Report immediately if callback is provided (preserves pragma suppression with original locations)
@@ -918,6 +982,7 @@ internal sealed class LoggerMethod
             public readonly List<LoggerParameter> TemplateParameters = new();
             public readonly Dictionary<string, string> TemplateMap = new(StringComparer.OrdinalIgnoreCase);
             public readonly List<string> TemplateList = new();
+            public readonly List<LoggerMethodTypeParameter> TypeParameters = new();
             public string Name = string.Empty;
             public string UniqueName = string.Empty;
             public string Message = string.Empty;
@@ -935,6 +1000,7 @@ internal sealed class LoggerMethod
                 TemplateParameters = TemplateParameters.Select(p => p.ToSpec()).ToImmutableEquatableArray(),
                 TemplateMap = TemplateMap.Select(kvp => new KeyValuePairEquatable<string, string>(kvp.Key, kvp.Value)).ToImmutableEquatableArray(),
                 TemplateList = TemplateList.ToImmutableEquatableArray(),
+                TypeParameters = TypeParameters.Select(tp => tp.ToSpec()).ToImmutableEquatableArray(),
                 Name = Name,
                 UniqueName = UniqueName,
                 Message = Message,
@@ -957,6 +1023,7 @@ internal sealed record LoggerMethodSpec : IEquatable<LoggerMethodSpec>
             public required ImmutableEquatableArray<LoggerParameterSpec> TemplateParameters { get; init; }
             public required ImmutableEquatableArray<KeyValuePairEquatable<string, string>> TemplateMap { get; init; }
             public required ImmutableEquatableArray<string> TemplateList { get; init; }
+            public required ImmutableEquatableArray<LoggerMethodTypeParameterSpec> TypeParameters { get; init; }
             public required string Name { get; init; }
             public required string UniqueName { get; init; }
             public required string Message { get; init; }
@@ -976,6 +1043,7 @@ public bool Equals(LoggerMethodSpec? other)
                        TemplateParameters.Equals(other.TemplateParameters) &&
                        TemplateMap.Equals(other.TemplateMap) &&
                        TemplateList.Equals(other.TemplateList) &&
+                       TypeParameters.Equals(other.TypeParameters) &&
                        Name == other.Name &&
                        UniqueName == other.UniqueName &&
                        Message == other.Message &&
@@ -994,6 +1062,7 @@ public override int GetHashCode()
                 hash = HashHelpers.Combine(hash, TemplateParameters.GetHashCode());
                 hash = HashHelpers.Combine(hash, TemplateMap.GetHashCode());
                 hash = HashHelpers.Combine(hash, TemplateList.GetHashCode());
+                hash = HashHelpers.Combine(hash, TypeParameters.GetHashCode());
                 hash = HashHelpers.Combine(hash, Name.GetHashCode());
                 hash = HashHelpers.Combine(hash, UniqueName.GetHashCode());
                 hash = HashHelpers.Combine(hash, Message.GetHashCode());
@@ -1102,6 +1171,44 @@ public override int GetHashCode()
             }
         }
 
+        /// <summary>
+        /// A type parameter of a generic logging method.
+        /// </summary>
+        internal sealed class LoggerMethodTypeParameter
+        {
+            public string Name = string.Empty;
+            public string? Constraints;
+
+            public LoggerMethodTypeParameterSpec ToSpec() => new LoggerMethodTypeParameterSpec
+            {
+                Name = Name,
+                Constraints = Constraints
+            };
+        }
+
+        /// <summary>
+        /// Immutable specification of a type parameter for incremental caching.
+        /// </summary>
+        internal sealed record LoggerMethodTypeParameterSpec : IEquatable<LoggerMethodTypeParameterSpec>
+        {
+            public required string Name { get; init; }
+            public required string? Constraints { get; init; }
+
+            public bool Equals(LoggerMethodTypeParameterSpec? other)
+            {
+                if (other is null) return false;
+                if (ReferenceEquals(this, other)) return true;
+                return Name == other.Name && Constraints == other.Constraints;
+            }
+
+            public override int GetHashCode()
+            {
+                int hash = Name.GetHashCode();
+                hash = HashHelpers.Combine(hash, Constraints?.GetHashCode() ?? 0);
+                return hash;
+            }
+        }
+
         /// <summary>
         /// Returns a non-randomized hash code for the given string.
         /// We always return a positive value.

src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Roslyn4.0.cs

@@ -259,6 +259,15 @@ private static LoggerClass FromSpec(LoggerClassSpec spec)
                     lm.TemplateList.Add(template);
                 }
 
+                foreach (var typeParamSpec in methodSpec.TypeParameters)
+                {
+                    lm.TypeParameters.Add(new LoggerMethodTypeParameter
+                    {
+                        Name = typeParamSpec.Name,
+                        Constraints = typeParamSpec.Constraints
+                    });
+                }
+
                 lc.Methods.Add(lm);
             }