[IDE] Print opaque result type as protocol composition

rdar://problem/49354663
(cherry picked from commit 8055583)

Author: rintaro

include/swift/AST/PrintOptions.h

@@ -263,9 +263,20 @@ struct PrintOptions {
   /// Whether to skip keywords with a prefix of underscore such as __consuming.
   bool SkipUnderscoredKeywords = false;
 
-  /// Whether to print declarations with opaque return types with a stable,
-  /// parsable internal syntax.
-  bool PrintStableReferencesToOpaqueReturnTypes = false;
+  /// How to print opaque return types.
+  enum class OpaqueReturnTypePrintingMode {
+    /// 'some P1 & P2'.
+    WithOpaqueKeyword,
+    /// 'P1 & P2'.
+    WithoutOpaqueKeyword,
+    /// Stable parsable internal syntax.
+    StableReference,
+    /// Description suitable for debugging.
+    Description
+  };
+
+  OpaqueReturnTypePrintingMode OpaqueReturnTypePrinting =
+      OpaqueReturnTypePrintingMode::WithOpaqueKeyword;
 
   /// Whether to print decl attributes that are only used internally,
   /// such as _silgen_name, transparent, etc.
@@ -524,7 +535,8 @@ struct PrintOptions {
     result.PrintInSILBody = true;
     result.PreferTypeRepr = false;
     result.PrintIfConfig = false;
-    result.PrintStableReferencesToOpaqueReturnTypes = true;
+    result.OpaqueReturnTypePrinting =
+        OpaqueReturnTypePrintingMode::StableReference;
     return result;
   }
 

lib/AST/ASTPrinter.cpp

@@ -107,7 +107,8 @@ PrintOptions PrintOptions::printParseableInterfaceFile() {
   result.FunctionDefinitions = true;
   result.CollapseSingleGetterProperty = false;
   result.VarInitializers = true;
-  result.PrintStableReferencesToOpaqueReturnTypes = true;
+  result.OpaqueReturnTypePrinting =
+      OpaqueReturnTypePrintingMode::StableReference;
 
   // We should print __consuming, __owned, etc for the module interface file.
   result.SkipUnderscoredKeywords = false;
@@ -3394,7 +3395,27 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       return;
     }
 
-    if (T->hasSimpleTypeRepr()) {
+    bool isSimple = T->hasSimpleTypeRepr();
+    if (isSimple && T->is<OpaqueTypeArchetypeType>()) {
+      auto opaqueTy = T->castTo<OpaqueTypeArchetypeType>();
+      auto opaqueDecl = opaqueTy->getDecl();
+      if (!opaqueDecl->hasName()) {
+        switch (Options.OpaqueReturnTypePrinting) {
+        case PrintOptions::OpaqueReturnTypePrintingMode::StableReference:
+        case PrintOptions::OpaqueReturnTypePrintingMode::Description:
+          isSimple = true;
+          break;
+        case PrintOptions::OpaqueReturnTypePrintingMode::WithOpaqueKeyword:
+          isSimple = false;
+          break;
+        case PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword: {
+          isSimple = opaqueTy->getConformsTo().size() < 2;
+        }
+        }
+      }
+    }
+
+    if (isSimple) {
       visit(T);
     } else {
       Printer << "(";
@@ -4157,7 +4178,7 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
   }
 
   void visitNestedArchetypeType(NestedArchetypeType *T) {
-    visit(T->getParent());
+    printWithParensIfNotSimple(T->getParent());
     Printer << ".";
     printArchetypeCommon(T);
   }
@@ -4167,16 +4188,28 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
   }
 
   void visitOpaqueTypeArchetypeType(OpaqueTypeArchetypeType *T) {
-    // Print the type by referencing the opaque decl's synthetic name, if we
-    // were asked to.
-    OpaqueTypeDecl *decl = T->getDecl();
-    
-    if (Options.PrintStableReferencesToOpaqueReturnTypes) {
+    switch (Options.OpaqueReturnTypePrinting) {
+    case PrintOptions::OpaqueReturnTypePrintingMode::WithOpaqueKeyword:
+      Printer << "some ";
+      LLVM_FALLTHROUGH;
+    case PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword: {
+      SmallVector<Type, 2> types;
+      for (auto proto : T->getConformsTo())
+        types.push_back(proto->TypeDecl::getDeclaredInterfaceType());
+
+      // Create and visit temporary ProtocolCompositionType.
+      auto composition =
+          ProtocolCompositionType::get(T->getASTContext(), types, false);
+      visit(composition);
+      return;
+    }
+    case PrintOptions::OpaqueReturnTypePrintingMode::StableReference: {
       // Print the source of the opaque return type as a mangled name.
       // We'll use type reconstruction while parsing the attribute to
       // turn this back into a reference to the naming decl for the opaque
       // type.
       Printer << "@_opaqueReturnTypeOf(";
+      OpaqueTypeDecl *decl = T->getDecl();
 
       Printer.printEscapedStringLiteral(
                                    decl->getOpaqueReturnTypeIdentifier().str());
@@ -4187,7 +4220,9 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
 
       Printer << u8") \U0001F9B8";
       printGenericArgs(T->getSubstitutions().getReplacementTypes());
-    } else {
+      return;
+    }
+    case PrintOptions::OpaqueReturnTypePrintingMode::Description: {
       // TODO(opaque): present opaque types with user-facing syntax. we should
       // probably print this as `some P` and record the fact that we printed that
       // so that diagnostics can add followup notes.
@@ -4201,6 +4236,8 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
                    [&] { Printer << ", "; });
         Printer << '>';
       }
+      return;
+    }
     }
   }
 

lib/IDE/CodeCompletion.cpp

@@ -1876,10 +1876,14 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
 
   void addTypeAnnotation(CodeCompletionResultBuilder &Builder, Type T) {
     T = T->getReferenceStorageReferent();
-    if (T->isVoid())
+    if (T->isVoid()) {
       Builder.addTypeAnnotation("Void");
-    else
-      Builder.addTypeAnnotation(T.getString());
+    } else {
+      PrintOptions PO;
+      PO.OpaqueReturnTypePrinting =
+          PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
+      Builder.addTypeAnnotation(T.getString(PO));
+    }
   }
 
   void addTypeAnnotationForImplicitlyUnwrappedOptional(
@@ -1897,6 +1901,8 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
     T = T->getReferenceStorageReferent();
     PrintOptions PO;
     PO.PrintOptionalAsImplicitlyUnwrapped = true;
+    PO.OpaqueReturnTypePrinting =
+        PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
     Builder.addTypeAnnotation(T.getString(PO) + suffix);
   }
 
@@ -1933,6 +1939,10 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
       // FIXME: Code completion should only deal with one or the other,
       // and not both.
       if (auto *archetypeType = t->getAs<ArchetypeType>()) {
+        // Don't erase opaque archetype.
+        if (isa<OpaqueTypeArchetypeType>(archetypeType))
+          return t;
+
         auto protos = archetypeType->getConformsTo();
         if (!protos.empty())
           return buildProtocolComposition(protos);
@@ -2476,6 +2486,8 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
               FD->getAttrs().hasAttribute<ImplicitlyUnwrappedOptionalAttr>();
 
           PrintOptions PO;
+          PO.OpaqueReturnTypePrinting =
+              PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
           PO.PrintOptionalAsImplicitlyUnwrapped = IsIUO;
           ResultType.print(OS, PO);
         }

lib/IDE/CodeCompletionResultBuilder.h

@@ -373,6 +373,8 @@ class CodeCompletionResultBuilder {
     PrintOptions PO;
     PO.SkipAttributes = true;
     PO.PrintOptionalAsImplicitlyUnwrapped = IsIUO;
+    PO.OpaqueReturnTypePrinting =
+        PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
     std::string TypeName = Ty->getString(PO);
     addChunkWithText(CodeCompletionString::Chunk::ChunkKind::CallParameterType,
                      TypeName);
@@ -385,6 +387,8 @@ class CodeCompletionResultBuilder {
       PrintOptions PO;
       PO.PrintFunctionRepresentationAttrs = false;
       PO.SkipAttributes = true;
+      PO.OpaqueReturnTypePrinting =
+          PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
       addChunkWithText(
           CodeCompletionString::Chunk::ChunkKind::CallParameterClosureType,
           AFT->getString(PO));