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thomhurst merged 2 commits into from
Sep 29, 2026
Merged

perf(source-gen): resolve parameter reflection info through a shared runtime helper #6923

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perf(source-gen): resolve parameter reflection info through a shared …
thomhurst Sep 29, 2026
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perf(source-gen): address review feedback on parameter reflection res…
thomhurst Sep 29, 2026
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44 changes: 1 addition & 43 deletions src/TUnit.Core.SourceGenerator/CodeGenerators/Writers/SourceInformationWriter.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,4 @@
using System.Collections.Immutable;
using Microsoft.CodeAnalysis;
using TUnit.Core.SourceGenerator.Enums;
using Microsoft.CodeAnalysis;
using TUnit.Core.SourceGenerator.Utilities;

namespace TUnit.Core.SourceGenerator.CodeGenerators.Writers;
Expand Down Expand Up @@ -58,46 +56,6 @@ public static void GenerateMethodInformation(ICodeWriter sourceCodeWriter,
sourceCodeWriter.AppendLine();
}

public static void GenerateMembers(ICodeWriter sourceCodeWriter, Compilation compilation, INamedTypeSymbol namedTypeSymbol, ImmutableArray<IParameterSymbol> parameters, IPropertySymbol? property, ArgumentsType argumentsType)
{
if (parameters.Length == 0 && property is null)
{
sourceCodeWriter.Append("[],");
return;
}

sourceCodeWriter.Append("[");

if (property is not null)
{
GeneratePropertyInformation(sourceCodeWriter, compilation, property, namedTypeSymbol);
}

foreach (var parameter in parameters)
{
GenerateParameterInformation(sourceCodeWriter, compilation, parameter, argumentsType, null);
}

sourceCodeWriter.Append("],");
}

public static void GeneratePropertyInformation(ICodeWriter sourceCodeWriter,
Compilation compilation, IPropertySymbol property, INamedTypeSymbol namedTypeSymbol)
{
MetadataGenerationHelper.WritePropertyMetadata(sourceCodeWriter, property, namedTypeSymbol);
sourceCodeWriter.Append(",");
}

public static void GenerateParameterInformation(ICodeWriter sourceCodeWriter,
Compilation context,
IParameterSymbol parameter, ArgumentsType argumentsType,
IDictionary<string, string>? genericSubstitutions)
{
// For now, use the generic version since it's what the existing code was doing
MetadataGenerationHelper.WriteParameterMetadataGeneric(sourceCodeWriter, parameter);
sourceCodeWriter.Append(",");
}

/// <summary>
/// Recursively generates parent ClassMetadata expression for nested types.
/// Returns null if the type has no containing type.
Expand Down
89 changes: 22 additions & 67 deletions src/TUnit.Core.SourceGenerator/Utilities/MetadataGenerationHelper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -211,87 +211,39 @@ public static string GenerateAssemblyMetadataGetOrAdd(IAssemblySymbol assembly)
return $"global::TUnit.Core.AssemblyMetadata.GetOrAdd(\"{assembly.Name}\", \"{assembly.Name}\")";
}

/// <summary>
/// Generates code for creating a ParameterMetadata instance (generic version).
/// Delegates to <see cref="WriteParameterMetadata"/> for consistency.
/// </summary>
public static void WriteParameterMetadataGeneric(ICodeWriter writer, IParameterSymbol parameter, IMethodSymbol? containingMethod = null)
{
WriteParameterMetadata(writer, parameter, containingMethod);
}

/// <summary>
/// Generates code for creating a ParameterMetadata instance via ParameterMetadataFactory.Create().
/// Reflection info is attached per method/constructor by <see cref="WriteReflectionInfoAttachStart"/>.
/// </summary>
public static void WriteParameterMetadata(ICodeWriter writer, IParameterSymbol parameter, IMethodSymbol? containingMethod = null)
private static void WriteParameterMetadata(ICodeWriter writer, IParameterSymbol parameter)
{
var safeType = CodeGenerationHelpers.ContainsTypeParameter(parameter.Type) ? "object" : parameter.Type.GloballyQualified();
var reflectionInfoExpr = GenerateReflectionInfoForParameter(parameter, containingMethod);

writer.Append($"global::TUnit.Core.ParameterMetadataFactory.Create(typeof({safeType}), \"{parameter.Name}\", {CodeGenerationHelpers.GenerateTypeInfo(parameter.Type)}, {parameter.Type.IsNullable().ToString().ToLowerInvariant()}, reflectionInfoFactory: static () => {reflectionInfoExpr})");
writer.Append($"global::TUnit.Core.ParameterMetadataFactory.Create(typeof({safeType}), \"{parameter.Name}\", {CodeGenerationHelpers.GenerateTypeInfo(parameter.Type)}, {parameter.Type.IsNullable().ToString().ToLowerInvariant()})");
}

/// <summary>
/// Generates reflection info code for a parameter.
/// Delegates to <see cref="GenerateParameterInfoArrayExpression"/> to avoid duplicating the reflection lookup logic.
/// Writes the opening of a ParameterMetadataFactory.ForMethod/ForGenericMethod/ForConstructor call, which lazily
/// resolves the ParameterInfo of every parameter from a single shared method lookup on first access.
/// Must be followed by the ParameterMetadata[] array expression and a closing parenthesis.
/// </summary>
private static string GenerateReflectionInfoForParameter(IParameterSymbol parameter, IMethodSymbol? providedMethod = null)
private static void WriteReflectionInfoAttachStart(ICodeWriter writer, IMethodSymbol method)
{
var method = providedMethod ?? parameter.ContainingSymbol as IMethodSymbol;

if (method == null)
{
return "null!";
}

var parameterIndex = method.Parameters.IndexOf(parameter);
if (parameterIndex == -1)
{
return "null!";
}

var containingType = method.ContainingType.GloballyQualified();
var usesTypeParameters = method.Parameters.Any(p => CodeGenerationHelpers.ContainsTypeParameter(p.Type));

if (method.MethodKind == MethodKind.Constructor)
{
if (method.Parameters.Any(p => CodeGenerationHelpers.ContainsTypeParameter(p.Type)))
{
return $@"global::System.Linq.Enumerable.FirstOrDefault(typeof({containingType}).GetConstructors(), c => c.GetParameters().Length == {method.Parameters.Length})?.GetParameters()[{parameterIndex}]!";
}

var paramTypes = GenerateParameterTypesArrayForReflection(method);
return $@"typeof({containingType}).GetConstructor({paramTypes})!.GetParameters()[{parameterIndex}]";
}

if (method.TypeParameters.Length > 0 || method.Parameters.Any(p => CodeGenerationHelpers.ContainsTypeParameter(p.Type)))
{
return $@"global::System.Linq.Enumerable.FirstOrDefault(typeof({containingType}).GetMethods(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance | global::System.Reflection.BindingFlags.Static), m => m.Name == ""{method.Name}"" && m.GetParameters().Length == {method.Parameters.Length})?.GetParameters()[{parameterIndex}]!";
writer.Append($"global::TUnit.Core.ParameterMetadataFactory.ForConstructor(typeof({containingType}), {usesTypeParameters.ToString().ToLowerInvariant()}, ");
}

else if (method.TypeParameters.Length > 0 || usesTypeParameters)
{
var bindingFlags = method.IsStatic
? "global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static"
: "global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance";
var paramTypes = GenerateParameterTypesArrayForReflection(method);
return $@"typeof({containingType}).GetMethod(""{method.Name}"", {bindingFlags}, null, {paramTypes}, null)!.GetParameters()[{parameterIndex}]";
writer.Append($"global::TUnit.Core.ParameterMetadataFactory.ForGenericMethod(typeof({containingType}), \"{method.Name}\", ");
}
}


private static string GenerateParameterTypesArrayForReflection(IMethodSymbol method)
{
if (method.Parameters.Length == 0)
else
{
return "global::System.Type.EmptyTypes";
writer.Append($"global::TUnit.Core.ParameterMetadataFactory.ForMethod(typeof({containingType}), \"{method.Name}\", {method.IsStatic.ToString().ToLowerInvariant()}, ");
}

var paramTypes = method.Parameters.Select(p =>
{
var safeTypeName = p.Type.GloballyQualified();
return $"typeof({safeTypeName})";
});

return $"new global::System.Type[] {{ {string.Join(", ", paramTypes)} }}";
}

/// <summary>
Expand Down Expand Up @@ -369,6 +321,7 @@ private static void WriteParameterMetadataArrayForMethod(ICodeWriter writer, IMe
return;
}

WriteReflectionInfoAttachStart(writer, method);
writer.AppendLine("new global::TUnit.Core.ParameterMetadata[]");
writer.AppendLine("{");

Expand All @@ -379,7 +332,7 @@ private static void WriteParameterMetadataArrayForMethod(ICodeWriter writer, IMe
for (var i = 0; i < method.Parameters.Length; i++)
{
var param = method.Parameters[i];
WriteParameterMetadata(writer, param, method);
WriteParameterMetadata(writer, param);

if (i < method.Parameters.Length - 1)
{
Expand All @@ -390,7 +343,7 @@ private static void WriteParameterMetadataArrayForMethod(ICodeWriter writer, IMe
// Manually restore indent level
writer.SetIndentLevel(currentIndent);
writer.AppendLine();
writer.Append("}");
writer.Append("})");
}

/// <summary>
Expand All @@ -414,6 +367,7 @@ private static void WriteParameterMetadataArrayForConstructor(ICodeWriter writer
return;
}

WriteReflectionInfoAttachStart(writer, constructor);
writer.AppendLine("new global::TUnit.Core.ParameterMetadata[]");
writer.AppendLine("{");

Expand All @@ -424,7 +378,7 @@ private static void WriteParameterMetadataArrayForConstructor(ICodeWriter writer
for (var i = 0; i < constructor.Parameters.Length; i++)
{
var param = constructor.Parameters[i];
WriteParameterMetadata(writer, param, constructor);
WriteParameterMetadata(writer, param);

if (i < constructor.Parameters.Length - 1)
{
Expand All @@ -435,7 +389,7 @@ private static void WriteParameterMetadataArrayForConstructor(ICodeWriter writer
// Manually restore indent level
writer.SetIndentLevel(currentIndent);
writer.AppendLine();
writer.Append("}");
writer.Append("})");
}

/// <summary>
Expand All @@ -449,14 +403,15 @@ private static string GenerateParameterMetadataArrayForConstructor(IMethodSymbol
}

var writer = new CodeWriter("", includeHeader: false).SetIndentLevel(currentIndentLevel);
WriteReflectionInfoAttachStart(writer, constructor);
writer.AppendLine("new global::TUnit.Core.ParameterMetadata[]");
writer.AppendLine("{");
writer.Indent();

for (var i = 0; i < constructor.Parameters.Length; i++)
{
var param = constructor.Parameters[i];
WriteParameterMetadata(writer, param, constructor);
WriteParameterMetadata(writer, param);

if (i < constructor.Parameters.Length - 1)
{
Expand All @@ -465,7 +420,7 @@ private static string GenerateParameterMetadataArrayForConstructor(IMethodSymbol
}

writer.Unindent();
writer.Append("}");
writer.Append("})");

return writer.ToString();
}
Expand Down
20 changes: 18 additions & 2 deletions src/TUnit.Core/Models/TestModels/ParameterMetadata.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,17 +27,33 @@ public record ParameterMetadata([DynamicallyAccessedMembers(DynamicallyAccessedM
public ParameterInfo ReflectionInfo
{
get => field ??= ReflectionInfoFactory?.Invoke()
?? throw new InvalidOperationException(
$"ReflectionInfo for parameter '{Name}' was not set and no ReflectionInfoFactory was provided.");
?? ReflectionInfoResolver?.Get(ReflectionInfoIndex)
?? throw CreateMissingReflectionInfoException();
set;
} = null!;

private InvalidOperationException CreateMissingReflectionInfoException()
{
return ReflectionInfoResolver is { } resolver
? new InvalidOperationException(
$"ReflectionInfo for parameter '{Name}' (index {ReflectionInfoIndex}) could not be resolved: {resolver.Describe()} was not found.")
: new InvalidOperationException(
$"ReflectionInfo for parameter '{Name}' was not set and no ReflectionInfoFactory was provided.");
}

/// <summary>
/// Lazy factory for ReflectionInfo. Set by source generator to defer reflection to first access.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public Func<ParameterInfo>? ReflectionInfoFactory { get; init; }

/// <summary>
/// Shared per-method lazy lookup attached by <see cref="ParameterMetadataFactory"/> for generated code.
/// </summary>
internal ParameterInfoResolver? ReflectionInfoResolver { get; set; }

internal int ReflectionInfoIndex { get; set; }

public bool IsParams => CachedIsParams ?? ReflectionInfo.IsDefined(typeof(ParamArrayAttribute), false);
public bool IsOptional => CachedIsOptional ?? ReflectionInfo.IsOptional;
public bool IsNullable { get; init; }
Expand Down
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