[Distributed] Improve error messages for protocol conformances

Author: ktoso

include/swift/AST/Decl.h

@@ -169,6 +169,7 @@ enum class DescriptiveDeclKind : uint8_t {
   Method,
   StaticMethod,
   ClassMethod,
+  DistributedMethod,
   Getter,
   Setter,
   Addressor,

lib/AST/Decl.cpp

@@ -258,7 +258,11 @@ DescriptiveDeclKind Decl::getDescriptiveKind() const {
      // We have a method.
      switch (func->getCorrectStaticSpelling()) {
      case StaticSpellingKind::None:
-       return DescriptiveDeclKind::Method;
+       if (func->isDistributed()) {
+         return DescriptiveDeclKind::DistributedMethod;
+       } else {
+         return DescriptiveDeclKind::Method;
+       }
      case StaticSpellingKind::KeywordStatic:
        return DescriptiveDeclKind::StaticMethod;
      case StaticSpellingKind::KeywordClass:
@@ -320,6 +324,7 @@ StringRef Decl::getDescriptiveKindName(DescriptiveDeclKind K) {
   ENTRY(Method, "instance method");
   ENTRY(StaticMethod, "static method");
   ENTRY(ClassMethod, "class method");
+  ENTRY(DistributedMethod, "distributed method");
   ENTRY(Getter, "getter");
   ENTRY(Setter, "setter");
   ENTRY(WillSet, "willSet observer");

test/Distributed/distributed_actor_protocol_isolation.swift

@@ -12,8 +12,11 @@ typealias DefaultActorTransport = AnyActorTransport
 
 protocol LocalProto {
   func local()
+  // expected-note@-1{{mark the protocol requirement 'local()' 'async throws' in order witness it with 'distributed' function declared in distributed actor 'DAD'}}
   func localAsync() async
+  // expected-note@-1{{mark the protocol requirement 'localAsync()' 'throws' in order witness it with 'distributed' function declared in distributed actor 'DAD'}}
   func localThrows() throws
+  // expected-note@-1{{mark the protocol requirement 'localThrows()' 'async' in order witness it with 'distributed' function declared in distributed actor 'DAD'}}
   func localAsyncThrows() async throws
 }
 
@@ -56,6 +59,21 @@ distributed actor DAL: LocalProto {
   // expected-error@-1{{actor-isolated instance method 'localAsyncThrows()' cannot be used to satisfy a protocol requirement}}
 }
 
+distributed actor DAD: LocalProto {
+  distributed func local() {}
+  // expected-error@-1{{distributed actor-isolated distributed method 'local()' cannot be used to satisfy a protocol requirement}}
+  // expected-note@-2{{add 'nonisolated' to 'local()' to make this distributed method not isolated to the actor}}
+
+  distributed func localAsync() async {}
+  // expected-error@-1{{distributed actor-isolated distributed method 'localAsync()' cannot be used to satisfy a protocol requirement}}
+
+  distributed func localThrows() throws {}
+  // expected-error@-1{{distributed actor-isolated distributed method 'localThrows()' cannot be used to satisfy a protocol requirement}}
+  // expected-note@-2{{add 'nonisolated' to 'localThrows()' to make this distributed method not isolated to the actor}}
+
+  distributed func localAsyncThrows() async throws {} // ok!
+}
+
 // ==== ------------------------------------------------------------------------
 
 distributed actor DA2: DistProtoDistributedActor {