[APINotes] Add support for handling Clang modules carrying all versions of APINotes

include/swift/Basic/LangOptions.h

@@ -1127,6 +1127,11 @@ namespace swift {
     /// globals.
     bool EnableConstValueImporting = true;
 
+    /// Whether the importer should expect all APINotes to be wrapped
+    /// in versioned attributes, where the importer must select the appropriate
+    /// ones to apply.
+    bool LoadVersionIndependentAPINotes = false;
+
     /// Return a hash code of any components from these options that should
     /// contribute to a Swift Bridging PCH hash.
     llvm::hash_code getPCHHashComponents() const {

include/swift/Option/FrontendOptions.td

@@ -685,6 +685,9 @@ def emit_pch : Flag<["-"], "emit-pch">,
 def pch_disable_validation : Flag<["-"], "pch-disable-validation">,
   HelpText<"Disable validating the persistent PCH">;
 
+def version_independent_apinotes : Flag<["-"], "version-independent-apinotes">,
+  HelpText<"Input clang modules carry all versioned APINotes">;
+
 def disable_sil_ownership_verifier : Flag<["-"], "disable-sil-ownership-verifier">,
   HelpText<"Do not verify ownership invariants during SIL Verification ">;
 

lib/ClangImporter/ClangImporter.cpp

@@ -787,6 +787,10 @@ void importer::getNormalInvocationArguments(
     invocationArgStrs.push_back("-iapinotes-modules");
     invocationArgStrs.push_back(path.str().str());
   }
+
+  if (importerOpts.LoadVersionIndependentAPINotes)
+    invocationArgStrs.insert(invocationArgStrs.end(),
+                             {"-fswift-version-independent-apinotes"});
 }
 
 static void

lib/ClangImporter/ImportDecl.cpp

@@ -70,6 +70,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
+#include "clang/Sema/SemaDiagnostic.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Lookup.h"
 
@@ -9481,6 +9482,72 @@ static bool isUsingMacroName(clang::SourceManager &SM,
   return content == MacroName;
 }
 
+static void filterUsableVersionedAttrs(
+    const clang::NamedDecl *clangDecl, llvm::VersionTuple currentVersion,
+    std::set<clang::SwiftVersionedAdditionAttr *> &applicableVersionedAttrSet) {
+  // Scan through Swift-Versioned clang attributes and select which one to apply
+  // if multiple candidates exist.
+  SmallVector<clang::SwiftVersionedAdditionAttr *, 4> swiftVersionedAttributes;
+  for (auto attr : clangDecl->attrs())
+    if (auto versionedAttr = dyn_cast<clang::SwiftVersionedAdditionAttr>(attr))
+      swiftVersionedAttributes.push_back(versionedAttr);
+
+  // An attribute version is valid to apply if it is greater than the current
+  // version or is unversioned
+  auto applicableVersion =
+      [currentVersion](clang::VersionTuple attrVersion) -> bool {
+    return attrVersion.empty() || attrVersion >= currentVersion;
+  };
+
+  // We have a better attribute option if there exists another versioned attr
+  // wrapper for this attribute kind with a valid version that is lower than the
+  // one of the attribute we are considering
+  auto haveBetterAttr = [swiftVersionedAttributes, applicableVersion](
+                            clang::VersionTuple attrVersion,
+                            clang::attr::Kind attrKind) -> bool {
+    for (auto VAI = swiftVersionedAttributes.begin(),
+              VAE = swiftVersionedAttributes.end();
+         VAI != VAE; ++VAI) {
+      auto otherVersionedAttr = *VAI;
+      auto otherAttrKind = otherVersionedAttr->getAdditionalAttr()->getKind();
+      auto otherAttrVersion = otherVersionedAttr->getVersion();
+      // Same exact attribute, ignore
+      if (otherAttrKind == attrKind && otherAttrVersion == attrVersion)
+        continue;
+
+      // For a matching attribute kind, an un-versioned attribute
+      // never takes precedence over an exsiting valid versioned one.
+      if (otherAttrKind == attrKind && !attrVersion.empty() &&
+          otherAttrVersion.empty())
+        continue;
+      if (otherAttrKind == attrKind && applicableVersion(otherAttrVersion) &&
+          attrVersion.empty())
+        return true;
+
+      // For two versioned attributes of the same kind, the one with the lower
+      // applicable version takes precedence.
+      if (otherAttrKind == attrKind && applicableVersion(otherAttrVersion) &&
+          otherAttrVersion < attrVersion)
+        return true;
+    }
+    return false;
+  };
+
+  for (auto VAI = swiftVersionedAttributes.begin(),
+            VAE = swiftVersionedAttributes.end();
+       VAI != VAE; ++VAI) {
+    auto versionedAttr = *VAI;
+    auto attrKind = versionedAttr->getAdditionalAttr()->getKind();
+    auto attrVersion = versionedAttr->getVersion();
+    if (!applicableVersion(attrVersion))
+      continue;
+    else if (haveBetterAttr(attrVersion, attrKind))
+      continue;
+    else
+      applicableVersionedAttrSet.insert(versionedAttr);
+  }
+}
+
 void ClangImporter::Implementation::importAttributesFromClangDeclToSynthesizedSwiftDecl(Decl *sourceDecl, Decl* synthesizedDecl)
 {
   // sourceDecl->getClangDecl() can be null because some lazily instantiated cases like C++ members that were instantiated from using-shadow-decls have no corresponding Clang decl.
@@ -9791,6 +9858,76 @@ void ClangImporter::Implementation::importAttributes(
   }
 }
 
+static void applyTypeAndNullabilityAPINotes(
+    const clang::NamedDecl *ClangDecl, clang::Sema &Sema,
+    const ImportNameVersion CurrentImporterVersion) {
+  // When importing from a module built with version-independent APINotes
+  // payload, the decl will carry all possible versioned notes, without directly
+  // applying any of them. For "type" and "nullability" notes, we must apply
+  // them first, here, since they change the actual type of the decl as seen
+  // downstream.
+  //
+  // Other kinds of notes will be handled in `importAttributes`.
+  for (clang::NamedDecl::attr_iterator AI = ClangDecl->attr_begin(),
+                                       AE = ClangDecl->attr_end();
+       AI != AE; ++AI) {
+    if (!isa<clang::SwiftTypeAttr>(*AI) &&
+        !isa<clang::SwiftNullabilityAttr>(*AI))
+      continue;
+
+    // Apply Type APINotes
+    if (auto typeRenameAttr = dyn_cast<clang::SwiftTypeAttr>(*AI)) {
+      Sema.ApplyAPINotesType(const_cast<clang::NamedDecl *>(ClangDecl),
+                             typeRenameAttr->getTypeString());
+    }
+
+    // Apply Nullability APINotes
+    if (auto nullabilityAttr = dyn_cast<clang::SwiftNullabilityAttr>(*AI)) {
+      clang::NullabilityKind nullability;
+      switch (nullabilityAttr->getKind()) {
+      case clang::SwiftNullabilityAttr::Kind::NonNull:
+        nullability = clang::NullabilityKind::NonNull;
+        break;
+      case clang::SwiftNullabilityAttr::Kind::Nullable:
+        nullability = clang::NullabilityKind::Nullable;
+        break;
+      case clang::SwiftNullabilityAttr::Kind::Unspecified:
+        nullability = clang::NullabilityKind::Unspecified;
+        break;
+      case clang::SwiftNullabilityAttr::Kind::NullableResult:
+        nullability = clang::NullabilityKind::NullableResult;
+        break;
+      }
+
+      Sema.ApplyNullability(const_cast<clang::NamedDecl *>(ClangDecl),
+                            nullability);
+    }
+  }
+}
+
+static void canonicalizeVersionedSwiftAttributes(
+    const clang::NamedDecl *ClangDecl,
+    const ImportNameVersion CurrentImporterVersion) {
+  if (!ClangDecl->hasAttrs())
+    return;
+
+  // Filter out only the versioned attributes which apply to the
+  // current compilation's language version
+  std::set<clang::SwiftVersionedAdditionAttr *> applicableVersionedAttrSet;
+  filterUsableVersionedAttrs(ClangDecl,
+                             CurrentImporterVersion.asClangVersionTuple(),
+                             applicableVersionedAttrSet);
+
+  // Drop all versioned addition attributes and re-add
+  // above-filtered out applicable attributes in a non-versioned
+  // form in order to ensure all downstream clients
+  // get the expected attribute view.
+  auto mutableDecl = const_cast<clang::NamedDecl *>(ClangDecl);
+  mutableDecl->dropAttrs<clang::SwiftVersionedAdditionAttr>();
+  for (const auto &attr : applicableVersionedAttrSet)
+    mutableDecl->addAttr(attr->getAdditionalAttr());
+}
+
 Decl *
 ClangImporter::Implementation::importDeclImpl(const clang::NamedDecl *ClangDecl,
                                               ImportNameVersion version,
@@ -9802,6 +9939,21 @@ ClangImporter::Implementation::importDeclImpl(const clang::NamedDecl *ClangDecl,
   if (ClangDecl->isInvalidDecl())
     return nullptr;
 
+  // If '-version-independent-apinotes' is used, the `ClangDecl`
+  // will be carrying various APINotes-sourced attributes wrapped
+  // in `SwiftVersionedAdditionAttr`. Filter out which ones are applicable
+  // for the current compilation version and rewrite the set of versioned
+  // attributes with the corresponding subset of only applicable wrapped
+  // attributes.
+  if (SwiftContext.ClangImporterOpts.LoadVersionIndependentAPINotes) {
+    canonicalizeVersionedSwiftAttributes(ClangDecl, CurrentVersion);
+    // When '-version-independent-apinotes' is used, "type" and "nullability"
+    // notes are applied by the client (Importer) instead of the producer of the
+    // Clang module we are consuming. Do so now, early, since these notes
+    // affect the decl's type and require mutation.
+    applyTypeAndNullabilityAPINotes(ClangDecl, getClangSema(), CurrentVersion);
+  }
+
   bool SkippedOverTypedef = false;
   Decl *Result = nullptr;
   if (auto *UnderlyingDecl = canSkipOverTypedef(*this, ClangDecl,

lib/Frontend/CompilerInvocation.cpp

@@ -2124,6 +2124,8 @@ static bool ParseClangImporterArgs(ClangImporterOptions &Opts, ArgList &Args,
     Opts.PCHDisableValidation |= Args.hasArg(OPT_pch_disable_validation);
   }
 
+  Opts.LoadVersionIndependentAPINotes |= Args.hasArg(OPT_version_independent_apinotes);
+
   if (FrontendOpts.DisableImplicitModules)
     Opts.DisableImplicitClangModules = true;
 

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -2013,6 +2013,12 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     GenericArgs.push_back(blocklist);
   }
 
+  // Inherit APINotes processing method
+  if (clangImporterOpts.LoadVersionIndependentAPINotes) {
+    GenericArgs.push_back("-version-independent-apinotes");
+    genericSubInvocation.getClangImporterOptions().LoadVersionIndependentAPINotes = true;
+  }  
+
   // Inherit the C++ interoperability mode.
   if (langOpts.EnableCXXInterop) {
     // Modelled after a reverse of validateCxxInteropCompatibilityMode

test/APINotes/basic_version_independent.swift

@@ -0,0 +1,49 @@
+// REQUIRES: objc_interop
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/InputClangModules)
+// RUN: split-file %s %t
+
+// - Fixup the input module file map
+// RUN: sed -e "s|INPUTSDIR|%/t/InputClangModules|g" %t/map.json.template > %t/map.json.template1
+// RUN: sed -e "s|STDLIBMOD|%/stdlib_module|g" %t/map.json.template1 > %t/map.json.template2
+// RUN: sed -e "s|ONONEMOD|%/ononesupport_module|g" %t/map.json.template2 > %t/map.json.template3
+// RUN: sed -e "s|CUSTOMFRAMEWORKS|%S/Inputs/custom-frameworks|g" %t/map.json.template3 > %t/map.json.template4
+// RUN: sed -e "s|SWIFTLIBDIR|%swift-lib-dir|g" %t/map.json.template4 > %t/map.json
+
+// - Set up explicit dependencies for Client
+// RUN: %target-swift-emit-pcm -module-name SwiftShims %swift-lib-dir/swift/shims/module.modulemap -o %t/InputClangModules/SwiftShims.pcm -Xcc -fswift-version-independent-apinotes
+
+// - Build the APINotesFrameworkTest module using verison-independent APINotes
+// RUN: %target-swift-emit-pcm -module-name APINotesFrameworkTest %S/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Modules/module.modulemap -o %t/InputClangModules/APINotesFrameworkTest.pcm -Xcc -I -Xcc %S/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers -Xcc -F -Xcc %S/Inputs/custom-frameworks -Xcc -fswift-version-independent-apinotes
+
+// - Build the client
+// RUN: %target-swift-frontend -typecheck -verify %t/client.swift -explicit-swift-module-map-file %t/map.json -disable-implicit-swift-modules -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import -version-independent-apinotes
+
+//--- map.json.template
+[
+  {
+      "moduleName": "Swift",
+      "modulePath": "STDLIBMOD",
+      "isFramework": false
+  },
+  {
+      "moduleName": "SwiftOnoneSupport",
+      "modulePath": "ONONEMOD",
+      "isFramework": false
+  },
+  {
+      "moduleName": "SwiftShims",
+      "isFramework": false,
+      "clangModuleMapPath": "SWIFTLIBDIR/swift/shims/module.modulemap",
+      "clangModulePath": "INPUTSDIR/SwiftShims.pcm"
+  },
+  {
+      "moduleName": "APINotesFrameworkTest",
+      "isFramework": true,
+      "clangModuleMapPath": "CUSTOMFRAMEWORKS/APINotesFrameworkTest.framework/Modules/module.modulemap",
+      "clangModulePath": "INPUTSDIR/APINotesFrameworkTest.pcm"
+  }  
+]
+
+//--- client.swift
+import APINotesFrameworkTest