[Sema] NFC: Remove GetDistributedMethodWitnessedProtocolRequirements (#85274)

This has been unused for over a year now (since #71801), let's just
remove it.

Author: hamishknight

include/swift/AST/Decl.h

@@ -8118,15 +8118,6 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
            getSILSynthesizeKind() == SILSynthesizeKind::DistributedActorFactory;
   }
 
-  /// Return a vector of distributed requirements that this distributed method
-  /// is implementing.
-  ///
-  /// If the method is witness to multiple requirements this is incorrect and
-  /// should be diagnosed during type-checking as it may make remoteCalls
-  /// ambiguous.
-  llvm::ArrayRef<ValueDecl *>
-  getDistributedMethodWitnessedProtocolRequirements() const;
-
   /// Determines whether this function is a 'remoteCall' function,
   /// which is used as ad-hoc protocol requirement by the
   /// 'DistributedActorSystem' protocol.

include/swift/AST/TypeCheckRequests.h

@@ -1598,27 +1598,6 @@ class GetDistributedActorConcreteArgumentDecodingMethodRequest :
   bool isCached() const { return true; }
 };
 
-/// Find out if a distributed method is implementing a distributed protocol
-/// requirement.
-class GetDistributedMethodWitnessedProtocolRequirements :
-    public SimpleRequest<GetDistributedMethodWitnessedProtocolRequirements,
-                         llvm::ArrayRef<ValueDecl *> (AbstractFunctionDecl *),
-                         RequestFlags::Cached> {
-public:
-  using SimpleRequest::SimpleRequest;
-
-private:
-  friend SimpleRequest;
-
-  llvm::ArrayRef<ValueDecl *> evaluate(
-      Evaluator &evaluator,
-      AbstractFunctionDecl *nominal) const;
-
-public:
-  // Caching
-  bool isCached() const { return true; }
-};
-
 /// Retrieve the static "shared" property within a global actor that provides
 /// the actor instance representing the global actor.
 ///

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -160,9 +160,6 @@ SWIFT_REQUEST(TypeChecker, GetDistributedActorSystemPropertyRequest,
 SWIFT_REQUEST(TypeChecker, GetDistributedRemoteCallTargetInitFunctionRequest,
               ConstructorDecl *(NominalTypeDecl *),
               Cached, NoLocationInfo)
-SWIFT_REQUEST(TypeChecker, GetDistributedMethodWitnessedProtocolRequirements,
-              ArrayRef<ValueDecl *> (AbstractFunctionDecl *),
-              Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, GetDistributedRemoteCallArgumentInitFunctionRequest,
               ConstructorDecl *(NominalTypeDecl *),
               Cached, NoLocationInfo)

lib/AST/DistributedDecl.cpp

@@ -453,21 +453,6 @@ bool swift::checkDistributedSerializationRequirementIsExactlyCodable(
       std::count(protocols.begin(), protocols.end(), decodable) == 1;
 }
 
-// TODO(distributed): probably can be removed?
-llvm::ArrayRef<ValueDecl *>
-AbstractFunctionDecl::getDistributedMethodWitnessedProtocolRequirements() const {
-  auto mutableThis = const_cast<AbstractFunctionDecl *>(this);
-
-  // Only a 'distributed' decl can witness 'distributed' protocol
-  if (!isDistributed()) {
-    return llvm::ArrayRef<ValueDecl *>();
-  }
-
-  return evaluateOrDefault(
-      getASTContext().evaluator,
-      GetDistributedMethodWitnessedProtocolRequirements(mutableThis), {});
-}
-
 /******************************************************************************/
 /********************* Ad-hoc protocol requirement checks *********************/
 /******************************************************************************/

lib/Sema/TypeCheckDistributed.cpp

@@ -945,21 +945,3 @@ GetDistributedActorConcreteArgumentDecodingMethodRequest::evaluate(
   /// witness
   return nullptr;
 }
-
-llvm::ArrayRef<ValueDecl *>
-GetDistributedMethodWitnessedProtocolRequirements::evaluate(
-    Evaluator &evaluator,
-    AbstractFunctionDecl *afd) const {
-  // Only a 'distributed' decl can witness 'distributed' protocol
-  assert(afd->isDistributed());
-  auto &C = afd->getASTContext();
-
-  auto result = llvm::SmallVector<ValueDecl *, 1>();
-  for (auto witnessedRequirement : afd->getSatisfiedProtocolRequirements()) {
-    if (witnessedRequirement->isDistributed()) {
-      result.push_back(witnessedRequirement);
-    }
-  }
-
-  return C.AllocateCopy(result);
-}