[APINotes] Support SwiftImportAs for C++ structs

This allows annotating C++ types as e.g. immortal references using API Notes.

This is based on the original patch by Zoe (411d3ab).

rdar://114933812

Author: egorzhdan

clang/include/clang/APINotes/Types.h

@@ -662,6 +662,10 @@ class TagInfo : public CommonTypeInfo {
   unsigned IsFlagEnum : 1;
 
 public:
+  std::optional<std::string> SwiftImportAs;
+  std::optional<std::string> SwiftRetainOp;
+  std::optional<std::string> SwiftReleaseOp;
+
   std::optional<EnumExtensibilityKind> EnumExtensibility;
 
   TagInfo() : HasFlagEnum(0), IsFlagEnum(0) {}
@@ -679,6 +683,13 @@ class TagInfo : public CommonTypeInfo {
   TagInfo &operator|=(const TagInfo &RHS) {
     static_cast<CommonTypeInfo &>(*this) |= RHS;
 
+    if (!SwiftImportAs)
+      SwiftImportAs = RHS.SwiftImportAs;
+    if (!SwiftRetainOp)
+      SwiftRetainOp = RHS.SwiftRetainOp;
+    if (!SwiftReleaseOp)
+      SwiftReleaseOp = RHS.SwiftReleaseOp;
+
     if (!HasFlagEnum)
       setFlagEnum(RHS.isFlagEnum());
 
@@ -695,6 +706,9 @@ class TagInfo : public CommonTypeInfo {
 
 inline bool operator==(const TagInfo &LHS, const TagInfo &RHS) {
   return static_cast<const CommonTypeInfo &>(LHS) == RHS &&
+         LHS.SwiftImportAs == RHS.SwiftImportAs &&
+         LHS.SwiftRetainOp == RHS.SwiftRetainOp &&
+         LHS.SwiftReleaseOp == RHS.SwiftReleaseOp &&
          LHS.isFlagEnum() == RHS.isFlagEnum() &&
          LHS.EnumExtensibility == RHS.EnumExtensibility;
 }

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 = 24; // EnumExtensibility + FlagEnum
+const uint16_t VERSION_MINOR = 25; // SwiftImportAs
 
 using IdentifierID = llvm::PointerEmbeddedInt<unsigned, 31>;
 using IdentifierIDField = llvm::BCVBR<16>;

clang/lib/APINotes/APINotesReader.cpp

@@ -536,6 +536,28 @@ namespace {
             static_cast<EnumExtensibilityKind>((payload & 0x3) - 1);
       }
 
+      unsigned ImportAsLength =
+          endian::readNext<uint16_t, little, unaligned>(data);
+      if (ImportAsLength > 0) {
+        info.SwiftImportAs = std::string(reinterpret_cast<const char *>(data),
+                                         ImportAsLength - 1);
+        data += ImportAsLength - 1;
+      }
+      unsigned RetainOpLength =
+          endian::readNext<uint16_t, little, unaligned>(data);
+      if (RetainOpLength > 0) {
+        info.SwiftRetainOp = std::string(reinterpret_cast<const char *>(data),
+                                         RetainOpLength - 1);
+        data += RetainOpLength - 1;
+      }
+      unsigned ReleaseOpLength =
+          endian::readNext<uint16_t, little, unaligned>(data);
+      if (ReleaseOpLength > 0) {
+        info.SwiftReleaseOp = std::string(reinterpret_cast<const char *>(data),
+                                          ReleaseOpLength - 1);
+        data += ReleaseOpLength - 1;
+      }
+
       readCommonTypeInfo(data, info);
       return info;
     }

clang/lib/APINotes/APINotesWriter.cpp

@@ -1146,7 +1146,10 @@ class CommonTypeTableInfo
 class TagTableInfo : public CommonTypeTableInfo<TagTableInfo, TagInfo> {
 public:
   unsigned getUnversionedInfoSize(const TagInfo &TI) {
-    return 1 + getCommonTypeInfoSize(TI);
+    return 2 + (TI.SwiftImportAs ? TI.SwiftImportAs->size() : 0) +
+           2 + (TI.SwiftRetainOp ? TI.SwiftRetainOp->size() : 0) +
+           2 + (TI.SwiftReleaseOp ? TI.SwiftReleaseOp->size() : 0) +
+           1 + getCommonTypeInfoSize(TI);
   }
 
   void emitUnversionedInfo(raw_ostream &OS, const TagInfo &TI) {
@@ -1164,6 +1167,25 @@ class TagTableInfo : public CommonTypeTableInfo<TagTableInfo, TagInfo> {
 
     writer.write<uint8_t>(Flags);
 
+    if (auto ImportAs = TI.SwiftImportAs) {
+      writer.write<uint16_t>(ImportAs->size() + 1);
+      OS.write(ImportAs->c_str(), ImportAs->size());
+    } else {
+      writer.write<uint16_t>(0);
+    }
+    if (auto RetainOp = TI.SwiftRetainOp) {
+      writer.write<uint16_t>(RetainOp->size() + 1);
+      OS.write(RetainOp->c_str(), RetainOp->size());
+    } else {
+      writer.write<uint16_t>(0);
+    }
+    if (auto ReleaseOp = TI.SwiftReleaseOp) {
+      writer.write<uint16_t>(ReleaseOp->size() + 1);
+      OS.write(ReleaseOp->c_str(), ReleaseOp->size());
+    } else {
+      writer.write<uint16_t>(0);
+    }
+
     emitCommonTypeInfo(OS, TI);
   }
 };

clang/lib/APINotes/APINotesYAMLCompiler.cpp

@@ -527,6 +527,9 @@ struct Tag {
   std::optional<bool> SwiftPrivate;
   std::optional<StringRef> SwiftBridge;
   std::optional<StringRef> NSErrorDomain;
+  std::optional<std::string> SwiftImportAs;
+  std::optional<std::string> SwiftRetainOp;
+  std::optional<std::string> SwiftReleaseOp;
   std::optional<EnumExtensibilityKind> EnumExtensibility;
   std::optional<bool> FlagEnum;
   std::optional<EnumConvenienceAliasKind> EnumConvenienceKind;
@@ -557,6 +560,9 @@ template <> struct MappingTraits<Tag> {
     IO.mapOptional("SwiftName", T.SwiftName, StringRef(""));
     IO.mapOptional("SwiftBridge", T.SwiftBridge);
     IO.mapOptional("NSErrorDomain", T.NSErrorDomain);
+    IO.mapOptional("SwiftImportAs", T.SwiftImportAs);
+    IO.mapOptional("SwiftReleaseOp", T.SwiftReleaseOp);
+    IO.mapOptional("SwiftRetainOp", T.SwiftRetainOp);
     IO.mapOptional("EnumExtensibility", T.EnumExtensibility);
     IO.mapOptional("FlagEnum", T.FlagEnum);
     IO.mapOptional("EnumKind", T.EnumConvenienceKind);
@@ -1129,6 +1135,27 @@ namespace {
         if (convertCommonType(t, tagInfo, t.Name))
           continue;
 
+        if ((t.SwiftRetainOp.has_value() || t.SwiftReleaseOp.has_value()) &&
+            !t.SwiftImportAs) {
+          emitError(llvm::Twine("should declare SwiftImportAs to use "
+                                "SwiftRetainOp and SwiftReleaseOp (for ") +
+                    t.Name + ")");
+          continue;
+        }
+        if (t.SwiftReleaseOp.has_value() != t.SwiftRetainOp.has_value()) {
+          emitError(llvm::Twine("should declare both SwiftReleaseOp and "
+                                "SwiftRetainOp (for ") +
+                    t.Name + ")");
+          continue;
+        }
+
+        if (t.SwiftImportAs)
+          tagInfo.SwiftImportAs = t.SwiftImportAs;
+        if (t.SwiftRetainOp)
+          tagInfo.SwiftRetainOp = t.SwiftRetainOp;
+        if (t.SwiftReleaseOp)
+          tagInfo.SwiftReleaseOp = t.SwiftReleaseOp;
+
         if (t.EnumConvenienceKind) {
           if (t.EnumExtensibility) {
             emitError(llvm::Twine(

clang/lib/Sema/SemaAPINotes.cpp

@@ -628,6 +628,22 @@ static void ProcessAPINotes(Sema &S, ObjCMethodDecl *D,
 static void ProcessAPINotes(Sema &S, TagDecl *D,
                             const api_notes::TagInfo &info,
                             VersionedInfoMetadata metadata) {
+  if (auto ImportAs = info.SwiftImportAs) {
+    auto str = "import_" + ImportAs.value();
+    auto attr = SwiftAttrAttr::Create(S.Context, str);
+    D->addAttr(attr);
+  }
+  if (auto RetainOp = info.SwiftRetainOp) {
+    auto str = "retain:" + RetainOp.value();
+    auto attr = SwiftAttrAttr::Create(S.Context, str);
+    D->addAttr(attr);
+  }
+  if (auto ReleaseOp = info.SwiftReleaseOp) {
+    auto str = "release:" + ReleaseOp.value();
+    auto attr = SwiftAttrAttr::Create(S.Context, str);
+    D->addAttr(attr);
+  }
+
   if (auto extensibility = info.EnumExtensibility) {
     using api_notes::EnumExtensibilityKind;
     bool shouldAddAttribute = (*extensibility != EnumExtensibilityKind::None);

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

@@ -0,0 +1,9 @@
+---
+Name: SwiftImportAs
+Tags:
+- Name: ImmortalRefType
+  SwiftImportAs: reference
+- Name: RefCountedType
+  SwiftImportAs: reference
+  SwiftReleaseOp: RCRelease
+  SwiftRetainOp: RCRetain

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

@@ -0,0 +1,6 @@
+struct ImmortalRefType {};
+
+struct RefCountedType { int value; };
+
+inline void RCRetain(RefCountedType *x) { x->value++; }
+inline void RCRelease(RefCountedType *x) { x->value--; }

clang/test/APINotes/Inputs/Headers/module.modulemap

@@ -25,3 +25,7 @@ module ModuleWithWrongCasePrivate {
 module Namespaces {
   header "Namespaces.h"
 }
+
+module SwiftImportAs {
+  header "SwiftImportAs.h"
+}

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

@@ -0,0 +1,16 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -fsyntax-only -I %S/Inputs/Headers %s -x c++
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -fsyntax-only -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter ImmortalRefType | FileCheck -check-prefix=CHECK-IMMORTAL %s
+// RUN: %clang_cc1 -fmodules -fblocks -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fdisable-module-hash -fapinotes-modules -fsyntax-only -I %S/Inputs/Headers %s -x c++ -ast-dump -ast-dump-filter RefCountedType | FileCheck -check-prefix=CHECK-REF-COUNTED %s
+
+#include <SwiftImportAs.h>
+
+// CHECK-IMMORTAL: Dumping ImmortalRefType:
+// CHECK-IMMORTAL-NEXT: CXXRecordDecl {{.+}} imported in SwiftImportAs {{.+}} struct ImmortalRefType
+// CHECK-IMMORTAL: SwiftAttrAttr {{.+}} <<invalid sloc>> "import_reference"
+
+// CHECK-REF-COUNTED: Dumping RefCountedType:
+// CHECK-REF-COUNTED-NEXT: CXXRecordDecl {{.+}} imported in SwiftImportAs {{.+}} struct RefCountedType
+// CHECK-REF-COUNTED: SwiftAttrAttr {{.+}} <<invalid sloc>> "import_reference"
+// CHECK-REF-COUNTED: SwiftAttrAttr {{.+}} <<invalid sloc>> "retain:RCRetain"
+// CHECK-REF-COUNTED: SwiftAttrAttr {{.+}} <<invalid sloc>> "release:RCRelease"