Spec: https://github.com/dotnet/roslyn/blob/features/interceptors/docs/features/interceptors.md (in-flight PRs may have more recent revisions)

• <Features>InterceptorsPreview</Features> flag - FeatureFlag
• Test intercepting a call with the same method which is already being called. - SelfInterception
• Test with a large number of intercepted calls (to ensure perf is not quadratic) - EndToEndTests.Interceptors
• Confirm the signature compatibility rules (are dynamic and object compatible, as they are in OHI?)
  • Yes. A warning is issued instead of an error when types differ in ways that are insignificant to the runtime. SignatureMismatch_06.
  • dynamic vs. object
  • Confirm the expected behavior for tuple name differences (SignatureMismatch_07 currently has no warnings)
  • test with nint vs. IntPtr difference - SignatureMismatch_08
• params differences - ParamsMismatch_
• Nullability warnings - SignatureMismatch_04 and SignatureMismatch_05
• Obsolete - ObsoleteInterceptor
• Caller attributes - CallerInfo
• Default parameter values from interceptor do not affect the call-site - DefaultArguments_
• #line directives ignored - LineDirective_
• Path mapping -- test various combinations of the following conditions - PathMapping_ and PathNormalization_
  • Confirm /pathmap and #line design with team
  • Pathmap replacement is all forward slashes
  • Pathmap replacement is all backslashes
  • Pathmap replacement is a mix of forward and backslashes
  • SyntaxTree.FilePath is absolute
  • SyntaxTree.FilePath is relative
  • InterceptsLocationAttribute path is all forward slashes
  • InterceptsLocationAttribute path is all backslashes slashes
  • InterceptsLocationAttribute path is a mix of forward and backslashes
  • InterceptsLocationAttribute path is a suffix of some SyntaxTree.FilePath
  • InterceptsLocationAttribute path is a suffix of a mapped path
  • InterceptsLocationAttribute path exactly matches an unmapped path
• InterceptsLocation line, character out of range - InterceptsLocationBadAttributeArguments_01, InterceptsLocationBadPosition_
• InterceptsLocation line, character not in method name - InterceptsLocationBadPosition_
• Test with argument names that differ from interceptor parameter names - ParameterNameDifference
• Test reordered argument names at callsite - ArgumentLabels, ParameterNamesInDifferentOrder
• Test InterceptsLocation in metadata (ignored) - InterceptsLocationFromMetadata
• InterceptsLocation on lambda or local function - InterceptsLocation_BadMethodKind
• GetEnumerator, Dispose, Deconstruct cannot be intercepted - InterceptGetEnumerator, InterceptDispose, InterceptDeconstruct
• More calls that cannot be intercepted - GetAwaiter, GetResult, MoveNext, GetPinnableReference, Dispose, Slice, Select (in LINQ query)
• Semantic model and IOperation
  • Test that the interceptor symbol for an intercepted call is not given by public APIs
• EnC
  • Test that a call intercepted by a generator can move in source, and we can rerun the generator and successfully emit
  • Test that a hand-authored interception breaks when the call moves in source and we can't emit
  • Test that in a compilation with interceptors, an edit in a file which doesn't contain intercepted calls can be emitted
• Should some special methods not be intercepted? (for example GetValueOrDefault is recognized specially in CodeGenerator)
• Duplicates on same and distinct interceptors - DuplicateLocation_
• Parameter names differ or appear in a different order - ParameterNameDifference, ParameterNamesInDifferentOrder
• Intercept a generic method call - InterceptableGeneric_
• Generic interceptor - InterceptorCannotBeGeneric_
  • Interceptable has type parameter constraints InterceptableGeneric_03
  • Incorrect arity
  • Violated constraints
  • Note: this may change in Add design for interceptors with nonzero arity #68218. May be punted to after net8
• Inaccessible interceptor
• file local interceptor
• Interceptable explicit interface implementation - InterceptableExplicitImplementation
• Interceptable call is to a retargeting method
• Scoped and [UnscopedRef] differences - ScopedMismatch_
• Interceptor is an extern method - InterceptorExtern
• Interceptor is an abstract method - InterceptorAbstract
• Interceptor is an interface method - InterceptorInterface
• Interceptor is a virtual method - InterceptorVirtual_
• Interceptor is an override method - InterceptorOverride_
• Intercept struct method with 'ref this' and 'this' extension methods - InterpolatedStringHandler_ and SignatureMismatch_03
• Interpolated string handler attributes are ignored - InterpolatedStringHandler_
• Intercept extension call in reduced form with a non-extension static method - InterceptableExtensionMethod_InterceptorStaticMethod
• Intercept extension call in normal form with extension and non-extension static method - InterceptableExtensionMethod_InterceptorStaticMethod_NormalForm and InterceptableExtensionMethod_InterceptorExtensionMethod_NormalForm
• Intercept extension call with instance method
• Call to object.ReferenceEquals has special semantics - ReferenceEquals_
• Differences in modopts and modreqs between interceptable and interceptor
• Intercept nameof(X) as an operator (error) or a method call - InterceptableNameOf_
• Update compiler test plan
• Uses of invocation syntax which cannot be intercepted (dynamic, delegate, function pointer)? - InterceptableDelegateInvocation. TODO dynamic and function pointers.
• __arglist, __makeref, __refvalue, __reftype - InterceptableDoubleUnderscoreReservedIdentifiers
• Spec: should we require interceptors to be static methods?
• Spec: The spec says "scoped modifiers and [UnscopedRef] must be equivalent.", but the implementation uses more subtle rules
• Spec: add support for generics? - Add design for interceptors with nonzero arity #68218

  • roslyn/src/Compilers/CSharp/Portable/Symbols/MemberSignatureComparer.cs

    Line 387 in fbb07ae

    bool considerArity = true, // PROTOTYPE(ic): remove default value?

• Constructor initializers: public Widget() : base(), public Widget() : this(), public class Widget(int i) : Base(i) { }
• Rename to <Features>InterceptorsPreview</Features>
• Disallow UnmanagedCallersOnly on interceptor - InterceptorUnmanagedCallersOnly
• Case-sensitive compare for paths - InterceptsLocationBadPath_04
• InterceptsLocation from project reference - InterceptsLocationFromMetadata
• PDB test for "debugging into interceptor"
• Embed type from NoPIA assembly used as default value in:
  • intercepted method
  • intercepting method
• Interceptor and original method differ by ref/out/in
• Interceptor and original method differ by ref custom modifiers

  • roslyn/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_Call.cs

    Line 203 in fbb07ae

    || methodThisParameter.RefKind != interceptorThisParameterForCompare.RefKind: // PROTOTYPE(ic): and ref custom modifiers are equal?

• Permit static non-extension interceptors to be called as though they are extension methods

  • roslyn/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_Call.cs

    Line 217 in fbb07ae

    // PROTOTYPE(ic): use a symbol display format which includes the 'this' modifier?