/// <summary>
/// Checks if a given method implements IEqualityComparer.Equals or IEquatable.Equals.
/// </summary>
private static bool IsEqualsInterfaceImplementation(IMethodSymbol method, Compilation compilation)
{
if (method.Name != WellKnownMemberNames.ObjectEquals)
{
return(false);
}
int paramCount = method.Parameters.Length;
if (method.ReturnType.SpecialType == SpecialType.System_Boolean &&
(paramCount == 1 || paramCount == 2))
{
// Substitute the type of the first parameter of Equals in the generic interface and then check if that
// interface method is implemented by the given method.
INamedTypeSymbol iEqualityComparer = WellKnownTypes.GenericIEqualityComparer(compilation);
if (method.IsImplementationOfInterfaceMethod(method.Parameters.First().Type, iEqualityComparer, WellKnownMemberNames.ObjectEquals))
{
return(true);
}
// Substitute the type of the first parameter of Equals in the generic interface and then check if that
// interface method is implemented by the given method.
INamedTypeSymbol iEquatable = WellKnownTypes.GenericIEquatable(compilation);
if (method.IsImplementationOfInterfaceMethod(method.Parameters.First().Type, iEquatable, WellKnownMemberNames.ObjectEquals))
{
return(true);
}
}
return(false);
}
/// <summary>
/// Checks if a given method implements IEqualityComparer.GetHashCode or IHashCodeProvider.GetHashCode.
/// </summary>
/// <param name="method"></param>
/// <param name="compilation"></param>
/// <returns></returns>
private static bool IsGetHashCodeInterfaceImplementation(IMethodSymbol method, Compilation compilation)
{
if (method.Name != WellKnownMemberNames.ObjectGetHashCode)
{
return(false);
}
if (method.ReturnType.SpecialType == SpecialType.System_Int32 && method.Parameters.Length == 1)
{
// Substitute the type of the first parameter of Equals in the generic interface and then check if that
// interface method is implemented by the given method.
INamedTypeSymbol iEqualityComparer = WellKnownTypes.GenericIEqualityComparer(compilation);
if (method.IsImplementationOfInterfaceMethod(method.Parameters.First().Type, iEqualityComparer, WellKnownMemberNames.ObjectGetHashCode))
{
return(true);
}
INamedTypeSymbol iHashCodeProvider = WellKnownTypes.IHashCodeProvider(compilation);
if (method.IsImplementationOfInterfaceMethod(null, iHashCodeProvider, WellKnownMemberNames.ObjectGetHashCode))
{
return(true);
}
}
return(false);
}
public override void Initialize(AnalysisContext analysisContext)
{
analysisContext.EnableConcurrentExecution();
analysisContext.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
analysisContext.RegisterCompilationStartAction(compilationStartAnalysisContext =>
{
INamedTypeSymbol equalityComparerType = WellKnownTypes.GenericIEqualityComparer(compilationStartAnalysisContext.Compilation);
IMethodSymbol iEqualityComparerGetHashCodeMethod = equalityComparerType?.GetMembers("GetHashCode").Single() as IMethodSymbol;
// Analyze named types and fields.
compilationStartAnalysisContext.RegisterSymbolAction(symbolContext =>
{
AnalyzeSymbol(symbolContext.Symbol, symbolContext);
}, SymbolKind.NamedType, SymbolKind.Field);
// Analyze properties and methods, and their parameters.
compilationStartAnalysisContext.RegisterSymbolAction(symbolContext =>
{
var method = symbolContext.Symbol as IMethodSymbol;
if (method != null)
{
if (method.IsEqualsOverride())
{
// Ignore, given the method signature and parameter names are auto-generated by the IDE:
// public override bool Equals(object obj)
return;
}
if (IsIEqualityComparerGetHashCodeInterfaceImplementation(method, iEqualityComparerGetHashCodeMethod))
{
// Ignore, given the method signature and parameter names are auto-generated by the IDE:
// public int GetHashCode(SomeType obj)
return;
}
}
AnalyzeSymbol(symbolContext.Symbol, symbolContext);
ImmutableArray <IParameterSymbol> parameters = symbolContext.Symbol.Kind == SymbolKind.Property ?
((IPropertySymbol)symbolContext.Symbol).Parameters :
((IMethodSymbol)symbolContext.Symbol).Parameters;
foreach (IParameterSymbol param in parameters)
{
AnalyzeSymbol(param, symbolContext);
}
}, SymbolKind.Property, SymbolKind.Method);
});
}
