[Concurrency] Compute the source of actor isolation in ActorIsolationRequest.

Author: hborla

include/swift/AST/ActorIsolation.h

@@ -275,9 +275,13 @@ class ActorIsolation {
   void print(llvm::raw_ostream &os) const;
 
   void printForSIL(llvm::raw_ostream &os) const;
-
+  
+  /// Print the given isolation for diagnostics. If \c asNoun is \c false,
+  /// the participle adjective form is printed, e.g. "main actor-isolated".
+  /// Otherwise, the noun form is printed, e.g. "main actor isolation".
   void printForDiagnostics(llvm::raw_ostream &os,
-                           StringRef openingQuotationMark = "'") const;
+                           StringRef openingQuotationMark = "'",
+                           bool asNoun = false) const;
 
   SWIFT_DEBUG_DUMPER(dump());
 
@@ -287,9 +291,61 @@ class ActorIsolation {
   SWIFT_DEBUG_DUMPER(dumpForDiagnostics());
 };
 
+struct IsolationSource {
+  enum Kind : uint8_t {
+    /// Isolation is written in an explicit attribute.
+    Explicit,
+    /// Isolation is inferred from the enclosing lexical context.
+    LexicalContext,
+    /// Isolation is inferred from conformance to a protocol.
+    Conformance,
+    /// Isolation is inherited from a superclass.
+    Superclass,
+    /// Isolation is inferred from an overridden superclass method.
+    Override,
+    /// Isolation is inferred from \c @main.
+    MainFunction,
+    /// Isolation is inferred in top-level code.
+    TopLevelCode,
+    /// Something else.
+    None,
+  };
+
+  /// The declaration with the original isolation attribute.
+  ValueDecl *inferenceSource;
+  Kind kind;
+
+  IsolationSource(ValueDecl *inferenceSource = nullptr,
+                  Kind kind = Kind::None)
+      : inferenceSource(inferenceSource), kind(kind) {}
+
+  void printForDiagnostics(llvm::raw_ostream &os,
+                           StringRef openingQuotationMark = "'") const;
+};
+
+struct InferredActorIsolation {
+  ActorIsolation isolation;
+  IsolationSource source;
+
+  static InferredActorIsolation forUnspecified() {
+    return {
+      ActorIsolation::forUnspecified(),
+      IsolationSource()
+    };
+  }
+
+  bool preconcurrency() const {
+    return isolation.preconcurrency();
+  }
+};
+
 /// Determine how the given value declaration is isolated.
 ActorIsolation getActorIsolation(ValueDecl *value);
 
+/// Infer the actor isolation of the given declaration, including
+/// the source of isolation inference.
+InferredActorIsolation getInferredActorIsolation(ValueDecl *value);
+
 /// Trampoline for AbstractClosureExpr::getActorIsolation.
 ActorIsolation
 __AbstractClosureExpr_getActorIsolation(AbstractClosureExpr *CE);

include/swift/AST/DiagnosticEngine.h

@@ -140,6 +140,7 @@ namespace swift {
     VersionTuple,
     LayoutConstraint,
     ActorIsolation,
+    IsolationSource,
     Diagnostic,
     ClangDecl
   };
@@ -175,6 +176,7 @@ namespace swift {
       llvm::VersionTuple VersionVal;
       LayoutConstraint LayoutConstraintVal;
       ActorIsolation ActorIsolationVal;
+      IsolationSource IsolationSourceVal;
       DiagnosticInfo *DiagnosticVal;
       const clang::NamedDecl *ClangDecl;
     };
@@ -283,6 +285,11 @@ namespace swift {
         ActorIsolationVal(AI) {
     }
 
+    DiagnosticArgument(IsolationSource IS)
+      : Kind(DiagnosticArgumentKind::IsolationSource),
+        IsolationSourceVal(IS){
+    }
+
     DiagnosticArgument(DiagnosticInfo *D)
       : Kind(DiagnosticArgumentKind::Diagnostic),
         DiagnosticVal(D) {
@@ -402,6 +409,11 @@ namespace swift {
       return ActorIsolationVal;
     }
 
+    IsolationSource getAsIsolationSource() const {
+      assert(Kind == DiagnosticArgumentKind::IsolationSource);
+      return IsolationSourceVal;
+    }
+
     DiagnosticInfo *getAsDiagnostic() const {
       assert(Kind == DiagnosticArgumentKind::Diagnostic);
       return DiagnosticVal;

include/swift/AST/DiagnosticsSema.def

@@ -5535,6 +5535,10 @@ NOTE(actor_isolated_sync_func_value,none,
      "calls function of type %0 from outside of its actor context are "
      "implicitly asynchronous",
      (Type))
+NOTE(actor_isolation_source,none,
+     "%noun0 inferred from %1",
+     (ActorIsolation, IsolationSource))
+
 NOTE(note_distributed_actor_isolated_method,none,
      "distributed actor-isolated %kind0 declared here",
      (const ValueDecl *))

include/swift/AST/TypeCheckRequests.h

@@ -1536,15 +1536,16 @@ class GlobalActorAttributeRequest
 /// Determine the actor isolation for the given declaration.
 class ActorIsolationRequest :
     public SimpleRequest<ActorIsolationRequest,
-                         ActorIsolation(ValueDecl *),
+                         InferredActorIsolation(ValueDecl *),
                          RequestFlags::Cached> {
 public:
   using SimpleRequest::SimpleRequest;
 
 private:
   friend SimpleRequest;
 
-  ActorIsolation evaluate(Evaluator &evaluator, ValueDecl *value) const;
+  InferredActorIsolation evaluate(Evaluator &evaluator,
+                                  ValueDecl *value) const;
 
 public:
   // Caching

lib/AST/Decl.cpp

@@ -11295,10 +11295,15 @@ bool VarDecl::isSelfParamCaptureIsolated() const {
 }
 
 ActorIsolation swift::getActorIsolation(ValueDecl *value) {
+  return getInferredActorIsolation(value).isolation;
+}
+
+InferredActorIsolation
+swift::getInferredActorIsolation(ValueDecl *value) {
   auto &ctx = value->getASTContext();
   return evaluateOrDefault(
       ctx.evaluator, ActorIsolationRequest{value},
-      ActorIsolation::forUnspecified());
+      InferredActorIsolation::forUnspecified());
 }
 
 ActorIsolation swift::getActorIsolationOfContext(

lib/AST/DiagnosticEngine.cpp

@@ -1012,8 +1012,16 @@ static void formatDiagnosticArgument(StringRef Modifier,
         << FormatOpts.ClosingQuotationMark;
     break;
   case DiagnosticArgumentKind::ActorIsolation: {
-    assert(Modifier.empty() && "Improper modifier for ActorIsolation argument");
+    assert((Modifier.empty() || Modifier == "noun") &&
+           "Improper modifier for ActorIsolation argument");
     auto isolation = Arg.getAsActorIsolation();
+    isolation.printForDiagnostics(Out, FormatOpts.OpeningQuotationMark,
+                                  /*asNoun*/ Modifier == "noun");
+    break;
+  }
+  case DiagnosticArgumentKind::IsolationSource: {
+    assert(Modifier.empty() && "Improper modifier for IsolationSource argument");
+    auto isolation = Arg.getAsIsolationSource();
     isolation.printForDiagnostics(Out, FormatOpts.OpeningQuotationMark);
     break;
   }

lib/AST/TypeCheckRequests.cpp

@@ -1804,19 +1804,20 @@ ActorIsolation ActorIsolation::subst(SubstitutionMap subs) const {
 }
 
 void ActorIsolation::printForDiagnostics(llvm::raw_ostream &os,
-                                         StringRef openingQuotationMark) const {
+                                         StringRef openingQuotationMark,
+                                         bool asNoun) const {
   switch (*this) {
   case ActorIsolation::ActorInstance:
-    os << "actor-isolated";
+    os << "actor" << (asNoun ? " isolation" : "-isolated");
     break;
 
   case ActorIsolation::GlobalActor: {
     if (isMainActor()) {
-      os << "main actor-isolated";
+      os << "main actor" << (asNoun ? " isolation" : "-isolated");
     } else {
       Type globalActor = getGlobalActor();
       os << "global actor " << openingQuotationMark << globalActor.getString()
-         << openingQuotationMark << "-isolated";
+         << openingQuotationMark << (asNoun ? " isolation" : "-isolated");
     }
     break;
   }
@@ -1942,6 +1943,46 @@ void swift::simple_display(
   }
 }
 
+void IsolationSource::printForDiagnostics(
+    llvm::raw_ostream &os,
+    StringRef openingQuotationMark) const {
+  switch (this->kind) {
+  case IsolationSource::Explicit:
+  case IsolationSource::None:
+    return;
+
+  case IsolationSource::MainFunction:
+    os << "@main";
+    return;
+
+  case IsolationSource::TopLevelCode:
+    os << "top-level code";
+    return;
+
+  case IsolationSource::LexicalContext: {
+    os << "isolation inheritance from ";
+    break;
+  }
+
+  case IsolationSource::Conformance:
+    os << "conformance to ";
+    break;
+
+  case IsolationSource::Superclass:
+    os << "inheritance from ";
+    break;
+
+  case IsolationSource::Override:
+    os << "overriding ";
+    break;
+  }
+
+  os << Decl::getDescriptiveKindName(inferenceSource->getDescriptiveKind()) << " ";
+  os << openingQuotationMark;
+  inferenceSource->getName().printPretty(os);
+  os << openingQuotationMark;
+}
+
 bool swift::areTypesEqual(Type type1, Type type2) {
   if (!type1 || !type2)
     return !type1 && !type2;