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using System.Collections.Immutable;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
namespace Godot.SourceGenerators
{
[DiagnosticAnalyzer(LanguageNames.CSharp)]
public sealed class MustBeVariantAnalyzer : DiagnosticAnalyzer
{
public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
=> ImmutableArray.Create(
Common.GenericTypeArgumentMustBeVariantRule,
Common.GenericTypeParameterMustBeVariantAnnotatedRule,
Common.TypeArgumentParentSymbolUnhandledRule);
public override void Initialize(AnalysisContext context)
{
context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
context.EnableConcurrentExecution();
context.RegisterSyntaxNodeAction(AnalyzeNode, SyntaxKind.TypeArgumentList);
}
private void AnalyzeNode(SyntaxNodeAnalysisContext context)
{
// Ignore syntax inside comments
if (IsInsideDocumentation(context.Node))
return;
var typeArgListSyntax = (TypeArgumentListSyntax)context.Node;
// Method invocation or variable declaration that contained the type arguments
var parentSyntax = context.Node.Parent;
Helper.ThrowIfNull(parentSyntax);
var sm = context.SemanticModel;
var typeCache = new MarshalUtils.TypeCache(context.Compilation);
for (int i = 0; i < typeArgListSyntax.Arguments.Count; i++)
{
var typeSyntax = typeArgListSyntax.Arguments[i];
// Ignore omitted type arguments, e.g.: List<>, Dictionary<,>, etc
if (typeSyntax is OmittedTypeArgumentSyntax)
continue;
var typeSymbol = sm.GetSymbolInfo(typeSyntax).Symbol as ITypeSymbol;
Helper.ThrowIfNull(typeSymbol);
var parentSymbolInfo = sm.GetSymbolInfo(parentSyntax);
var parentSymbol = parentSymbolInfo.Symbol;
if (parentSymbol == null)
{
if (parentSymbolInfo.CandidateReason == CandidateReason.LateBound)
{
// Invocations on dynamic are late bound so we can't retrieve the symbol.
continue;
}
Helper.ThrowIfNull(parentSymbol);
}
if (!ShouldCheckTypeArgument(context, parentSyntax, parentSymbol, typeSyntax, typeSymbol, i))
{
return;
}
if (typeSymbol is ITypeParameterSymbol typeParamSymbol)
{
if (!typeParamSymbol.GetAttributes().Any(a => a.AttributeClass?.IsGodotMustBeVariantAttribute() ?? false))
{
context.ReportDiagnostic(Diagnostic.Create(
Common.GenericTypeParameterMustBeVariantAnnotatedRule,
typeSyntax.GetLocation(),
typeSymbol.ToDisplayString()
));
}
continue;
}
var marshalType = MarshalUtils.ConvertManagedTypeToMarshalType(typeSymbol, typeCache);
if (marshalType is null)
{
context.ReportDiagnostic(Diagnostic.Create(
Common.GenericTypeArgumentMustBeVariantRule,
typeSyntax.GetLocation(),
typeSymbol.ToDisplayString()
));
}
}
}
/// <summary>
/// Check if the syntax node is inside a documentation syntax.
/// </summary>
/// <param name="syntax">Syntax node to check.</param>
/// <returns><see langword="true"/> if the syntax node is inside a documentation syntax.</returns>
private bool IsInsideDocumentation(SyntaxNode? syntax)
{
while (syntax != null)
{
if (syntax is DocumentationCommentTriviaSyntax)
{
return true;
}
syntax = syntax.Parent;
}
return false;
}
/// <summary>
/// Check if the given type argument is being used in a type parameter that contains
/// the <c>MustBeVariantAttribute</c>; otherwise, we ignore the attribute.
/// </summary>
/// <param name="context">Context for a syntax node action.</param>
/// <param name="parentSyntax">The parent node syntax that contains the type node syntax.</param>
/// <param name="parentSymbol">The symbol retrieved for the parent node syntax.</param>
/// <param name="typeArgumentSyntax">The type node syntax of the argument type to check.</param>
/// <param name="typeArgumentSymbol">The symbol retrieved for the type node syntax.</param>
/// <param name="typeArgumentIndex"></param>
/// <returns><see langword="true"/> if the type must be variant and must be analyzed.</returns>
private bool ShouldCheckTypeArgument(
SyntaxNodeAnalysisContext context,
SyntaxNode parentSyntax,
ISymbol parentSymbol,
TypeSyntax typeArgumentSyntax,
ITypeSymbol typeArgumentSymbol,
int typeArgumentIndex)
{
ITypeParameterSymbol? typeParamSymbol = parentSymbol switch
{
IMethodSymbol methodSymbol when parentSyntax.Ancestors().Any(s => s is AttributeSyntax) &&
methodSymbol.ContainingType.TypeParameters.Length > 0
=> methodSymbol.ContainingType.TypeParameters[typeArgumentIndex],
IMethodSymbol { TypeParameters.Length: > 0 } methodSymbol
=> methodSymbol.TypeParameters[typeArgumentIndex],
INamedTypeSymbol { TypeParameters.Length: > 0 } typeSymbol
=> typeSymbol.TypeParameters[typeArgumentIndex],
_
=> null
};
if (typeParamSymbol != null)
{
return typeParamSymbol.GetAttributes()
.Any(a => a.AttributeClass?.IsGodotMustBeVariantAttribute() ?? false);
}
context.ReportDiagnostic(Diagnostic.Create(
Common.TypeArgumentParentSymbolUnhandledRule,
typeArgumentSyntax.GetLocation(),
parentSymbol.ToDisplayString()
));
return false;
}
}
}
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