[AST] Factor out printMemberwiseInit

Move the printing logic into libAST such that it can be used both by
the refactoring and by fix-it logic in Sema.

include/swift/AST/Decl.h

@@ -10191,6 +10191,10 @@ getAccessorNameForDiagnostic(AccessorDecl *accessor, bool article,
 StringRef getAccessorNameForDiagnostic(AccessorKind accessorKind, bool article,
                                        bool underscored);
 
+/// Retrieve a textual representation for a memberwise initializer in a given
+/// nominal decl.
+void printMemberwiseInit(NominalTypeDecl *nominal, llvm::raw_ostream &out);
+
 void simple_display(llvm::raw_ostream &out,
                     OptionSet<NominalTypeDecl::LookupDirectFlags> options);
 

lib/AST/Decl.cpp

@@ -13114,6 +13114,76 @@ MacroDiscriminatorContext::getParentOf(FreestandingMacroExpansion *expansion) {
       expansion->getPoundLoc(), expansion->getDeclContext());
 }
 
+void swift::printMemberwiseInit(NominalTypeDecl *nominal,
+                                llvm::raw_ostream &out) {
+  auto &ctx = nominal->getASTContext();
+  auto &SM = ctx.SourceMgr;
+
+  auto printMemberName = [](Identifier name, llvm::raw_ostream &OS) {
+    if (escapeIdentifierInContext(name, PrintNameContext::TypeMember)) {
+      OS << '`' << name << '`';
+    } else {
+      OS << name;
+    }
+  };
+
+  SmallVector<VarDecl *, 4> vars;
+  for (auto *var : nominal->getMemberwiseInitProperties()) {
+    // Skip printing lazy properties since we don't have a way of spelling
+    // their initialization in source (since we'd be initializing the backing
+    // variable).
+    if (var->getAttrs().hasAttribute<LazyAttr>())
+      continue;
+
+    vars.push_back(var);
+  }
+
+  out << "init(";
+
+  // Process the list of members, inserting commas as appropriate.
+  for (const auto &[idx, var] : llvm::enumerate(vars)) {
+    if (idx > 0)
+      out << ", ";
+
+    printMemberName(var->getName(), out);
+    out << ": ";
+
+    // Unconditionally print '@escaping' if we print out a function type -
+    // the assignments we generate below will escape this parameter.
+    auto ty = var->getTypeInContext();
+    if (ty->is<AnyFunctionType>())
+      out << "@" << TypeAttribute::getAttrName(TypeAttrKind::Escaping) << " ";
+
+    out << ty.getString();
+
+    bool hasAddedDefault = false;
+    if (auto *PBD = var->getParentPatternBinding()) {
+      auto idx = PBD->getPatternEntryIndexForVarDecl(var);
+      auto *init = PBD->getOriginalInit(idx);
+      if (auto range = init ? init->getSourceRange() : SourceRange()) {
+        auto charRange = Lexer::getCharSourceRangeFromSourceRange(SM, range);
+        out << " = " << SM.extractText(charRange);
+        hasAddedDefault = true;
+      }
+    }
+    if (!hasAddedDefault && ty->isOptional())
+      out << " = nil";
+  }
+
+  // Print the body.
+  out << ") {\n";
+  for (auto *var : vars) {
+    // self.<property> = <property>
+    auto name = var->getName();
+    out << "self.";
+    printMemberName(name, out);
+    out << " = ";
+    printMemberName(name, out);
+    out << "\n";
+  }
+  out << "}";
+}
+
 std::optional<Type>
 CatchNode::getThrownErrorTypeInContext(ASTContext &ctx) const {
   if (auto func = dyn_cast<AbstractFunctionDecl *>()) {

lib/Refactoring/MemberwiseInitLocalRefactoring.cpp

@@ -14,154 +14,50 @@
 
 using namespace swift::refactoring;
 
-namespace {
-struct MemberwiseParameter {
-  Identifier Name;
-  Type MemberType;
-  Expr *DefaultExpr;
-
-  MemberwiseParameter(Identifier name, Type type, Expr *initialExpr)
-      : Name(name), MemberType(type), DefaultExpr(initialExpr) {}
-};
-} // namespace
-
-static void printMemberName(Identifier name, llvm::raw_ostream &OS) {
-  if (escapeIdentifierInContext(name, PrintNameContext::TypeMember)) {
-    OS << '`' << name << '`';
-  } else {
-    OS << name;
-  }
-}
-
 static void generateMemberwiseInit(SourceEditConsumer &EditConsumer,
-                                   SourceManager &SM,
-                                   ArrayRef<MemberwiseParameter> memberVector,
+                                   SourceManager &SM, NominalTypeDecl *nominal,
                                    SourceLoc targetLocation) {
-
-  EditConsumer.accept(SM, targetLocation, "\ninternal init(");
-  auto insertMember = [&SM](const MemberwiseParameter &memberData,
-                            raw_ostream &OS, bool wantsSeparator) {
-    {
-      printMemberName(memberData.Name, OS);
-      OS << ": ";
-      // Unconditionally print '@escaping' if we print out a function type -
-      // the assignments we generate below will escape this parameter.
-      if (isa<AnyFunctionType>(memberData.MemberType->getCanonicalType())) {
-        OS << "@" << TypeAttribute::getAttrName(TypeAttrKind::Escaping) << " ";
-      }
-      OS << memberData.MemberType.getString();
-    }
-
-    bool HasAddedDefault = false;
-    if (auto *expr = memberData.DefaultExpr) {
-      if (expr->getSourceRange().isValid()) {
-        auto range = Lexer::getCharSourceRangeFromSourceRange(
-            SM, expr->getSourceRange());
-        OS << " = " << SM.extractText(range);
-        HasAddedDefault = true;
-      }
-    }
-    if (!HasAddedDefault && memberData.MemberType->isOptional()) {
-      OS << " = nil";
-    }
-
-    if (wantsSeparator) {
-      OS << ", ";
-    }
-  };
-
-  // Process the initial list of members, inserting commas as appropriate.
-  std::string Buffer;
-  llvm::raw_string_ostream OS(Buffer);
-  for (const auto &memberData : llvm::enumerate(memberVector)) {
-    bool wantsSeparator = (memberData.index() != memberVector.size() - 1);
-    insertMember(memberData.value(), OS, wantsSeparator);
-  }
-
-  // Synthesize the body.
-  OS << ") {\n";
-  for (auto &member : memberVector) {
-    // self.<property> = <property>
-    OS << "self.";
-    printMemberName(member.Name, OS);
-    OS << " = ";
-    printMemberName(member.Name, OS);
-    OS << "\n";
-  }
-  OS << "}\n";
+  llvm::SmallString<64> buffer;
+  llvm::raw_svector_ostream OS(buffer);
+  OS << "\ninternal ";
+  printMemberwiseInit(nominal, OS);
+  OS << "\n";
 
   // Accept the entire edit.
-  EditConsumer.accept(SM, targetLocation, OS.str());
+  EditConsumer.accept(SM, targetLocation, buffer);
 }
 
-static SourceLoc
-collectMembersForInit(ResolvedCursorInfoPtr CursorInfo,
-                      SmallVectorImpl<MemberwiseParameter> &memberVector) {
+static NominalTypeDecl *getMemberwiseNominal(ResolvedCursorInfoPtr CursorInfo) {
   auto ValueRefInfo = dyn_cast<ResolvedValueRefCursorInfo>(CursorInfo);
   if (!ValueRefInfo || !ValueRefInfo->getValueD())
-    return SourceLoc();
+    return nullptr;
 
-  NominalTypeDecl *nominalDecl =
-      dyn_cast<NominalTypeDecl>(ValueRefInfo->getValueD());
+  auto *nominalDecl = dyn_cast<NominalTypeDecl>(ValueRefInfo->getValueD());
   if (!nominalDecl || nominalDecl->getStoredProperties().empty() ||
       ValueRefInfo->isRef()) {
-    return SourceLoc();
+    return nullptr;
   }
-
-  SourceLoc bracesStart = nominalDecl->getBraces().Start;
-  if (!bracesStart.isValid())
-    return SourceLoc();
-
-  SourceLoc targetLocation = bracesStart.getAdvancedLoc(1);
-  if (!targetLocation.isValid())
-    return SourceLoc();
-
-  for (auto member : nominalDecl->getMemberwiseInitProperties()) {
-    auto varDecl = dyn_cast<VarDecl>(member);
-    if (!varDecl) {
-      continue;
-    }
-    if (varDecl->getAttrs().hasAttribute<LazyAttr>()) {
-      // Exclude lazy members from the memberwise initializer. This is
-      // inconsistent with the implicitly synthesized memberwise initializer but
-      // we think it makes more sense because otherwise the lazy variable's
-      // initializer gets evaluated eagerly.
-      continue;
-    }
-
-    auto patternBinding = varDecl->getParentPatternBinding();
-    if (!patternBinding)
-      continue;
-
-    const auto i = patternBinding->getPatternEntryIndexForVarDecl(varDecl);
-    Expr *defaultInit = nullptr;
-    if (patternBinding->isExplicitlyInitialized(i) ||
-        patternBinding->isDefaultInitializable()) {
-      defaultInit = patternBinding->getOriginalInit(i);
-    }
-
-    memberVector.emplace_back(varDecl->getName(), varDecl->getTypeInContext(),
-                              defaultInit);
-  }
-
-  return targetLocation;
+  return nominalDecl;
 }
 
 bool RefactoringActionMemberwiseInitLocalRefactoring::isApplicable(
     ResolvedCursorInfoPtr Tok, DiagnosticEngine &Diag) {
+  auto nominal = getMemberwiseNominal(Tok);
+  if (!nominal)
+    return false;
 
-  SmallVector<MemberwiseParameter, 8> memberVector;
-  return collectMembersForInit(Tok, memberVector).isValid();
+  return nominal->getBraces().isValid();
 }
 
 bool RefactoringActionMemberwiseInitLocalRefactoring::performChange() {
-
-  SmallVector<MemberwiseParameter, 8> memberVector;
-  SourceLoc targetLocation = collectMembersForInit(CursorInfo, memberVector);
-  if (targetLocation.isInvalid())
+  auto nominal = getMemberwiseNominal(CursorInfo);
+  if (!nominal)
     return true;
 
-  generateMemberwiseInit(EditConsumer, SM, memberVector, targetLocation);
+  auto targetLocation = nominal->getBraces().Start.getAdvancedLocOrInvalid(1);
+  if (!targetLocation.isValid())
+    return true;
 
+  generateMemberwiseInit(EditConsumer, SM, nominal, targetLocation);
   return false;
 }