[APINotes] Add SWIFT_RETURNS_(UN)RETAINED support (#118938)

Adding support to APINotes to annotate C++ methods and functions with
`swift_attr("returns_retained")` and `swift_attr("returns_unretained")`

rdar://141007510

Author: fahadnayyar

clang/include/clang/APINotes/Types.h

@@ -542,6 +542,9 @@ class FunctionInfo : public CommonEntityInfo {
   /// The result type of this function, as a C type.
   std::string ResultType;
 
+  /// Ownership convention for return value
+  std::string SwiftReturnOwnership;
+
   /// The function parameters.
   std::vector<ParamInfo> Params;
 
@@ -622,7 +625,8 @@ inline bool operator==(const FunctionInfo &LHS, const FunctionInfo &RHS) {
          LHS.NumAdjustedNullable == RHS.NumAdjustedNullable &&
          LHS.NullabilityPayload == RHS.NullabilityPayload &&
          LHS.ResultType == RHS.ResultType && LHS.Params == RHS.Params &&
-         LHS.RawRetainCountConvention == RHS.RawRetainCountConvention;
+         LHS.RawRetainCountConvention == RHS.RawRetainCountConvention &&
+         LHS.SwiftReturnOwnership == RHS.SwiftReturnOwnership;
 }
 
 inline bool operator!=(const FunctionInfo &LHS, const FunctionInfo &RHS) {

clang/lib/APINotes/APINotesFormat.h

@@ -24,7 +24,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// API notes file minor version number.
 ///
 /// When the format changes IN ANY WAY, this number should be incremented.
-const uint16_t VERSION_MINOR = 33; // SwiftEscapable
+const uint16_t VERSION_MINOR = 34; // SwiftReturnOwnership
 
 const uint8_t kSwiftConforms = 1;
 const uint8_t kSwiftDoesNotConform = 2;

clang/lib/APINotes/APINotesReader.cpp

@@ -373,6 +373,13 @@ void ReadFunctionInfo(const uint8_t *&Data, FunctionInfo &Info) {
       endian::readNext<uint16_t, llvm::endianness::little>(Data);
   Info.ResultType = std::string(Data, Data + ResultTypeLen);
   Data += ResultTypeLen;
+
+  unsigned SwiftReturnOwnershipLength =
+      endian::readNext<uint16_t, llvm::endianness::little>(Data);
+  Info.SwiftReturnOwnership = std::string(reinterpret_cast<const char *>(Data),
+                                          reinterpret_cast<const char *>(Data) +
+                                              SwiftReturnOwnershipLength);
+  Data += SwiftReturnOwnershipLength;
 }
 
 /// Used to deserialize the on-disk Objective-C method table.

clang/lib/APINotes/APINotesTypes.cpp

@@ -77,6 +77,8 @@ LLVM_DUMP_METHOD void FunctionInfo::dump(llvm::raw_ostream &OS) const {
      << "RawRetainCountConvention: " << RawRetainCountConvention << ' ';
   if (!ResultType.empty())
     OS << "Result Type: " << ResultType << ' ';
+  if (!SwiftReturnOwnership.empty())
+    OS << "SwiftReturnOwnership: " << SwiftReturnOwnership << ' ';
   if (!Params.empty())
     OS << '\n';
   for (auto &PI : Params)

clang/lib/APINotes/APINotesWriter.cpp

@@ -1093,6 +1093,7 @@ unsigned getFunctionInfoSize(const FunctionInfo &FI) {
   for (const auto &P : FI.Params)
     size += getParamInfoSize(P);
   size += sizeof(uint16_t) + FI.ResultType.size();
+  size += sizeof(uint16_t) + FI.SwiftReturnOwnership.size();
   return size;
 }
 
@@ -1118,6 +1119,9 @@ void emitFunctionInfo(raw_ostream &OS, const FunctionInfo &FI) {
 
   writer.write<uint16_t>(FI.ResultType.size());
   writer.write(ArrayRef<char>{FI.ResultType.data(), FI.ResultType.size()});
+  writer.write<uint16_t>(FI.SwiftReturnOwnership.size());
+  writer.write(ArrayRef<char>{FI.SwiftReturnOwnership.data(),
+                              FI.SwiftReturnOwnership.size()});
 }
 
 /// Used to serialize the on-disk global function table.

clang/lib/APINotes/APINotesYAMLCompiler.cpp

@@ -162,6 +162,7 @@ struct Method {
   bool DesignatedInit = false;
   bool Required = false;
   StringRef ResultType;
+  StringRef SwiftReturnOwnership;
 };
 
 typedef std::vector<Method> MethodsSeq;
@@ -196,6 +197,8 @@ template <> struct MappingTraits<Method> {
     IO.mapOptional("DesignatedInit", M.DesignatedInit, false);
     IO.mapOptional("Required", M.Required, false);
     IO.mapOptional("ResultType", M.ResultType, StringRef(""));
+    IO.mapOptional("SwiftReturnOwnership", M.SwiftReturnOwnership,
+                   StringRef(""));
   }
 };
 } // namespace yaml
@@ -291,6 +294,7 @@ struct Function {
   StringRef SwiftName;
   StringRef Type;
   StringRef ResultType;
+  StringRef SwiftReturnOwnership;
 };
 
 typedef std::vector<Function> FunctionsSeq;
@@ -313,6 +317,8 @@ template <> struct MappingTraits<Function> {
     IO.mapOptional("SwiftPrivate", F.SwiftPrivate);
     IO.mapOptional("SwiftName", F.SwiftName, StringRef(""));
     IO.mapOptional("ResultType", F.ResultType, StringRef(""));
+    IO.mapOptional("SwiftReturnOwnership", F.SwiftReturnOwnership,
+                   StringRef(""));
   }
 };
 } // namespace yaml
@@ -825,6 +831,7 @@ class YAMLConverter {
       emitError("'FactoryAsInit' is no longer valid; use 'SwiftName' instead");
 
     MI.ResultType = std::string(M.ResultType);
+    MI.SwiftReturnOwnership = std::string(M.SwiftReturnOwnership);
 
     // Translate parameter information.
     convertParams(M.Params, MI, MI.Self);
@@ -950,6 +957,7 @@ class YAMLConverter {
     convertNullability(Function.Nullability, Function.NullabilityOfRet, FI,
                        Function.Name);
     FI.ResultType = std::string(Function.ResultType);
+    FI.SwiftReturnOwnership = std::string(Function.SwiftReturnOwnership);
     FI.setRetainCountConvention(Function.RetainCountConvention);
   }
 

clang/lib/Sema/SemaAPINotes.cpp

@@ -511,6 +511,11 @@ static void ProcessAPINotes(Sema &S, FunctionOrMethod AnyFunc,
       AnyTypeChanged = true;
   }
 
+  // returns_(un)retained
+  if (!Info.SwiftReturnOwnership.empty())
+    D->addAttr(SwiftAttrAttr::Create(S.Context,
+                                     "returns_" + Info.SwiftReturnOwnership));
+
   // Result type override.
   QualType OverriddenResultType;
   if (Metadata.IsActive && !Info.ResultType.empty() &&

clang/test/APINotes/Inputs/Headers/SwiftImportAs.apinotes

@@ -3,6 +3,12 @@ Name: SwiftImportAs
 Tags:
 - Name: ImmortalRefType
   SwiftImportAs: reference
+  Methods:
+    - Name: methodReturningFrt__
+    - Name: methodReturningFrt_returns_unretained
+      SwiftReturnOwnership: unretained
+    - Name: methodReturningFrt_returns_retained
+      SwiftReturnOwnership: retained
 - Name: RefCountedType
   SwiftImportAs: reference
   SwiftReleaseOp: RCRelease
@@ -17,3 +23,10 @@ Tags:
   SwiftEscapable: false
 - Name: EscapableType
   SwiftEscapable: true
+
+Functions:
+  - Name: functionReturningFrt__
+  - Name: functionReturningFrt_returns_unretained
+    SwiftReturnOwnership: unretained
+  - Name: functionReturningFrt_returns_retained
+    SwiftReturnOwnership: retained

clang/test/APINotes/Inputs/Headers/SwiftImportAs.h

@@ -1,4 +1,13 @@
-struct ImmortalRefType {};
+struct ImmortalRefType {
+    ImmortalRefType * methodReturningFrt__(void);
+    ImmortalRefType * methodReturningFrt_returns_unretained(void);
+    ImmortalRefType * methodReturningFrt_returns_retained(void);
+};
+
+ImmortalRefType * functionReturningFrt__(void);
+ImmortalRefType * functionReturningFrt_returns_unretained(void);
+ImmortalRefType * functionReturningFrt_returns_retained(void);
+
 
 struct RefCountedType { int value; };
 

clang/test/APINotes/swift-import-as.cpp

@@ -6,6 +6,12 @@
 // RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter CopyableType | FileCheck -check-prefix=CHECK-COPYABLE %s
 // RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter NonEscapableType | FileCheck -check-prefix=CHECK-NON-ESCAPABLE %s
 // RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter EscapableType | FileCheck -check-prefix=CHECK-ESCAPABLE %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter functionReturningFrt__ | FileCheck -check-prefix=CHECK-FUNCTION-RETURNING-FRT %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter functionReturningFrt_returns_unretained | FileCheck -check-prefix=CHECK-FUNCTION-RETURNING-FRT-UNRETAINED %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter functionReturningFrt_returns_retained | FileCheck -check-prefix=CHECK-FUNCTION-RETURNING-FRT-RETAINED %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter methodReturningFrt__ | FileCheck -check-prefix=CHECK-METHOD-RETURNING-FRT %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter methodReturningFrt_returns_unretained | FileCheck -check-prefix=CHECK-METHOD-RETURNING-FRT-UNRETAINED %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter methodReturningFrt_returns_retained | FileCheck -check-prefix=CHECK-METHOD-RETURNING-FRT-RETAINED %s
 
 #include <SwiftImportAs.h>
 
@@ -36,3 +42,29 @@
 // CHECK-ESCAPABLE: Dumping EscapableType:
 // CHECK-ESCAPABLE-NEXT: CXXRecordDecl {{.+}} imported in SwiftImportAs {{.+}} struct EscapableType
 // CHECK-ESCAPABLE: SwiftAttrAttr {{.+}} "Escapable"
+
+// CHECK-FUNCTION-RETURNING-FRT: Dumping functionReturningFrt__:
+// CHECK-FUNCTION-RETURNING-FRT: FunctionDecl {{.+}} imported in SwiftImportAs functionReturningFrt__ 'ImmortalRefType *()'
+// CHECK-FUNCTION-RETURNING-FRT-NOT: `-SwiftAttrAttr {{.+}} "returns_unretained"
+// CHECK-FUNCTION-RETURNING-FRT-NOT: `-SwiftAttrAttr {{.+}} "returns_retained"
+
+// CHECK-FUNCTION-RETURNING-FRT-UNRETAINED: Dumping functionReturningFrt_returns_unretained:
+// CHECK-FUNCTION-RETURNING-FRT-UNRETAINED: FunctionDecl {{.+}} imported in SwiftImportAs functionReturningFrt_returns_unretained 'ImmortalRefType *()'
+// CHECK-FUNCTION-RETURNING-FRT-UNRETAINED: `-SwiftAttrAttr {{.+}} "returns_unretained"
+
+// CHECK-FUNCTION-RETURNING-FRT-RETAINED: Dumping functionReturningFrt_returns_retained:
+// CHECK-FUNCTION-RETURNING-FRT-RETAINED: FunctionDecl {{.+}} imported in SwiftImportAs functionReturningFrt_returns_retained 'ImmortalRefType *()'
+// CHECK-FUNCTION-RETURNING-FRT-RETAINED: `-SwiftAttrAttr {{.+}} "returns_retained"
+
+// CHECK-METHOD-RETURNING-FRT: Dumping ImmortalRefType::methodReturningFrt__:
+// CHECK-METHOD-RETURNING-FRT: CXXMethodDecl {{.+}} imported in SwiftImportAs methodReturningFrt__ 'ImmortalRefType *()'
+// CHECK-METHOD-RETURNING-FRT-NOT: `-SwiftAttrAttr {{.+}} "returns_unretained"
+// CHECK-METHOD-RETURNING-FRT-NOT: `-SwiftAttrAttr {{.+}} "returns_retained"
+
+// CHECK-METHOD-RETURNING-FRT-UNRETAINED: Dumping ImmortalRefType::methodReturningFrt_returns_unretained:
+// CHECK-METHOD-RETURNING-FRT-UNRETAINED: CXXMethodDecl {{.+}} imported in SwiftImportAs methodReturningFrt_returns_unretained 'ImmortalRefType *()'
+// CHECK-METHOD-RETURNING-FRT-UNRETAINED: `-SwiftAttrAttr {{.+}} "returns_unretained"
+
+// CHECK-METHOD-RETURNING-FRT-RETAINED: Dumping ImmortalRefType::methodReturningFrt_returns_retained:
+// CHECK-METHOD-RETURNING-FRT-RETAINED: CXXMethodDecl {{.+}} imported in SwiftImportAs methodReturningFrt_returns_retained 'ImmortalRefType *()'
+// CHECK-METHOD-RETURNING-FRT-RETAINED: `-SwiftAttrAttr {{.+}} "returns_retained"