/// <summary>
/// This method does the following set of operations in the specified order:
/// (1) GetAttributesToBind: Merge attributes from the given attributesSyntaxLists and filter out attributes by attribute target.
/// (2) BindAttributeTypes: Bind all the attribute types to enable early decode of certain well-known attributes by type.
/// (3) EarlyDecodeWellKnownAttributes: Perform early decoding of certain well-known attributes that could be queried by the binder in subsequent steps.
/// (NOTE: This step has the side effect of updating the symbol state based on the data extracted from well known attributes).
/// (4) GetAttributes: Bind the attributes (attribute arguments and constructor) using bound attribute types.
/// (5) DecodeWellKnownAttributes: Decode and validate bound well known attributes.
/// (NOTE: This step has the side effect of updating the symbol state based on the data extracted from well known attributes).
/// (6) StoreBoundAttributesAndDoPostValidation:
/// (a) Store the bound attributes in lazyCustomAttributes in a thread safe manner.
/// (b) Perform some additional post attribute validations, such as
/// 1) Duplicate attributes, attribute usage target validation, etc.
/// 2) Post validation for attributes dependant on other attributes
/// These validations cannot be performed prior to step 6(a) as we might need to
/// perform a GetAttributes() call on a symbol which can introduce a cycle in attribute binding.
/// We avoid this cycle by performing such validations in PostDecodeWellKnownAttributes after lazyCustomAttributes have been set.
/// NOTE: PostDecodeWellKnownAttributes SHOULD NOT change the symbol state.
/// </summary>
/// <remarks>
/// Current design of early decoding well-known attributes doesn't permit decoding attribute arguments/constructor as this can lead to binding cycles.
/// For well-known attributes used by the binder, where we need the decoded arguments, we must handle them specially in one of the following possible ways:
/// (a) Avoid decoding the attribute arguments during binding and delay the corresponding binder tasks to a separate post-pass executed after binding.
/// (b) As the cycles can be caused only when we are binding attribute arguments/constructor, special case the corresponding binder tasks based on the current BinderFlags.
/// </remarks>
/// <param name="attributesSyntaxLists"></param>
/// <param name="lazyCustomAttributesBag"></param>
/// <param name="symbolPart">Specific part of the symbol to which the attributes apply, or <see cref="AttributeLocation.None"/> if the attributes apply to the symbol itself.</param>
/// <param name="earlyDecodingOnly">Indicates that only early decoding should be performed. WARNING: the resulting bag will not be sealed.</param>
/// <returns>Flag indicating whether lazyCustomAttributes were stored on this thread. Caller should check for this flag and perform NotePartComplete if true.</returns>
internal bool LoadAndValidateAttributes(
OneOrMany<SyntaxList<AttributeListSyntax>> attributesSyntaxLists,
ref CustomAttributesBag<CSharpAttributeData> lazyCustomAttributesBag,
AttributeLocation symbolPart = AttributeLocation.None,
bool earlyDecodingOnly = false)
{
var diagnostics = DiagnosticBag.GetInstance();
var compilation = this.DeclaringCompilation;
ImmutableArray<Binder> binders;
ImmutableArray<AttributeSyntax> attributesToBind = this.GetAttributesToBind(attributesSyntaxLists, symbolPart, diagnostics, compilation, out binders);
Debug.Assert(!attributesToBind.IsDefault);
ImmutableArray<CSharpAttributeData> boundAttributes;
WellKnownAttributeData wellKnownAttributeData;
if (attributesToBind.Any())
{
Debug.Assert(!binders.IsDefault);
Debug.Assert(binders.Length == attributesToBind.Length);
// Initialize the bag so that data decoded from early attributes can be stored onto it.
if (lazyCustomAttributesBag == null)
{
Interlocked.CompareExchange(ref lazyCustomAttributesBag, new CustomAttributesBag<CSharpAttributeData>(), null);
}
// Bind the attribute types and then early decode them.
int totalAttributesCount = attributesToBind.Length;
var attributeTypesBuilder = new NamedTypeSymbol[totalAttributesCount];
Binder.BindAttributeTypes(binders, attributesToBind, this, attributeTypesBuilder, diagnostics);
ImmutableArray<NamedTypeSymbol> boundAttributeTypes = attributeTypesBuilder.AsImmutableOrNull();
this.EarlyDecodeWellKnownAttributeTypes(boundAttributeTypes, attributesToBind);
this.PostEarlyDecodeWellKnownAttributeTypes();
// Bind the attribute in two stages - early and normal.
var attributesBuilder = new CSharpAttributeData[totalAttributesCount];
// Early bind and decode some well-known attributes.
EarlyWellKnownAttributeData earlyData = this.EarlyDecodeWellKnownAttributes(binders, boundAttributeTypes, attributesToBind, symbolPart, attributesBuilder);
Debug.Assert(!attributesBuilder.Contains((attr) => attr != null && attr.HasErrors));
// Store data decoded from early bound well-known attributes.
// TODO: what if this succeeds on another thread, not ours?
lazyCustomAttributesBag.SetEarlyDecodedWellKnownAttributeData(earlyData);
if (earlyDecodingOnly)
{
diagnostics.Free(); //NOTE: dropped.
return false;
}
// Bind attributes.
Binder.GetAttributes(binders, attributesToBind, boundAttributeTypes, attributesBuilder, diagnostics);
boundAttributes = attributesBuilder.AsImmutableOrNull();
// All attributes must be bound by now.
Debug.Assert(!boundAttributes.Any((attr) => attr == null));
// Validate attribute usage and Decode remaining well-known attributes.
wellKnownAttributeData = this.ValidateAttributeUsageAndDecodeWellKnownAttributes(binders, attributesToBind, boundAttributes, diagnostics, symbolPart);
// Store data decoded from remaining well-known attributes.
// TODO: what if this succeeds on another thread but not this thread?
lazyCustomAttributesBag.SetDecodedWellKnownAttributeData(wellKnownAttributeData);
}
else if (earlyDecodingOnly)
{
diagnostics.Free(); //NOTE: dropped.
return false;
}
else
{
boundAttributes = ImmutableArray<CSharpAttributeData>.Empty;
wellKnownAttributeData = null;
Interlocked.CompareExchange(ref lazyCustomAttributesBag, CustomAttributesBag<CSharpAttributeData>.WithEmptyData(), null);
this.PostEarlyDecodeWellKnownAttributeTypes();
}
this.PostDecodeWellKnownAttributes(boundAttributes, attributesToBind, diagnostics, symbolPart, wellKnownAttributeData);
// Store attributes into the bag.
bool lazyAttributesStoredOnThisThread = false;
if (lazyCustomAttributesBag.SetAttributes(boundAttributes))
{
this.RecordPresenceOfBadAttributes(boundAttributes);
this.AddDeclarationDiagnostics(diagnostics);
lazyAttributesStoredOnThisThread = true;
if (lazyCustomAttributesBag.IsEmpty) lazyCustomAttributesBag = CustomAttributesBag<CSharpAttributeData>.Empty;
}
Debug.Assert(lazyCustomAttributesBag.IsSealed);
diagnostics.Free();
return lazyAttributesStoredOnThisThread;
}
