[Serialization] Track whether a cross-reference came from Clang (#17377)

Cross-references are identified by their containing module, with the
assumption that two modules will never have the same name. However, an
overlay has the same name as its underlying Clang module, which means
that there can be two declarations with the same name, the same type,
and the same module name. This is the underlying cause of the
'UIEdgeInsetsZero' problem, but it also affects the CloudKit overlay.

By tracking a bit that just says "this came from Clang", we're able
to resolve otherwise ambiguous cross-references.

(Why didn't we do it this way all along? Because if a declaration
moves from Clang to Swift or vice versa, that would break the
cross-reference. But that's only interesting if the swiftmodule format
is meant to be persistent across changing dependencies, and it looks
like we're moving away from that anyway. It's also a little weird for
SerializedModuleLoader to have special cases for Clang, but this isn't
the first.)

Note that I'm not reverting the UIEdgeInsetsZero workaround here; the
end state will have that coming just from UIKit as originally
described.

rdar://problem/40839486
(cherry picked from commit 6b89415)

Author: jrose-apple

include/swift/Serialization/ModuleFormat.h

@@ -55,7 +55,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t VERSION_MINOR = 413; // Last change: Remove discriminator from LocalDeclTableInfo.
+const uint16_t VERSION_MINOR = 414; // Last change: track whether xrefs come from Clang
 
 using DeclIDField = BCFixed<31>;
 
@@ -1316,21 +1316,24 @@ namespace decls_block {
     XREF_TYPE_PATH_PIECE,
     IdentifierIDField, // name
     IdentifierIDField, // private discriminator
-    BCFixed<1>         // restrict to protocol extension
+    BCFixed<1>,        // restrict to protocol extension
+    BCFixed<1>         // imported from Clang?
   >;
 
   using XRefValuePathPieceLayout = BCRecordLayout<
     XREF_VALUE_PATH_PIECE,
     TypeIDField,       // type
     IdentifierIDField, // name
     BCFixed<1>,        // restrict to protocol extension
+    BCFixed<1>,        // imported from Clang?
     BCFixed<1>         // static?
   >;
 
   using XRefInitializerPathPieceLayout = BCRecordLayout<
     XREF_INITIALIZER_PATH_PIECE,
     TypeIDField,             // type
     BCFixed<1>,              // restrict to protocol extension
+    BCFixed<1>,              // imported from Clang?
     CtorInitializerKindField // initializer kind
   >;
 

lib/Serialization/Deserialization.cpp

@@ -1176,7 +1176,8 @@ static bool reExportedToSameModule(const ModuleDecl *fromModule,
 /// from Clang can also appear in any module.
 static void filterValues(Type expectedTy, ModuleDecl *expectedModule,
                          CanGenericSignature expectedGenericSig, bool isType,
-                         bool inProtocolExt, bool isStatic,
+                         bool inProtocolExt, bool importedFromClang,
+                         bool isStatic,
                          Optional<swift::CtorInitializerKind> ctorInit,
                          SmallVectorImpl<ValueDecl *> &values) {
   CanType canTy;
@@ -1198,6 +1199,8 @@ static void filterValues(Type expectedTy, ModuleDecl *expectedModule,
       return true;
     if (value->isStatic() != isStatic)
       return true;
+    if (value->hasClangNode() != importedFromClang)
+      return true;
 
     if (value->getAttrs().hasAttribute<ForbidSerializingReferenceAttr>())
       return true;
@@ -1275,13 +1278,14 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
     TypeID TID = 0;
     bool isType = (recordID == XREF_TYPE_PATH_PIECE);
     bool inProtocolExt = false;
+    bool importedFromClang = false;
     bool isStatic = false;
     if (isType)
       XRefTypePathPieceLayout::readRecord(scratch, IID, privateDiscriminator,
-                                          inProtocolExt);
+                                          inProtocolExt, importedFromClang);
     else
       XRefValuePathPieceLayout::readRecord(scratch, TID, IID, inProtocolExt,
-                                           isStatic);
+                                           importedFromClang, isStatic);
 
     DeclBaseName name = getDeclBaseName(IID);
     pathTrace.addValue(name);
@@ -1309,8 +1313,8 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
                                   NL_QualifiedDefault | NL_KnownNoDependency,
                                   /*typeResolver=*/nullptr, values);
     }
-    filterValues(filterTy, nullptr, nullptr, isType, inProtocolExt, isStatic,
-                 None, values);
+    filterValues(filterTy, nullptr, nullptr, isType, inProtocolExt,
+                 importedFromClang, isStatic, None, values);
     break;
   }
 
@@ -1364,13 +1368,14 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
       switch (recordID) {
       case XREF_TYPE_PATH_PIECE: {
         IdentifierID IID;
-        XRefTypePathPieceLayout::readRecord(scratch, IID, None, None);
+        XRefTypePathPieceLayout::readRecord(scratch, IID, None, None, None);
         result = getIdentifier(IID);
         break;
       }
       case XREF_VALUE_PATH_PIECE: {
         IdentifierID IID;
-        XRefValuePathPieceLayout::readRecord(scratch, None, IID, None, None);
+        XRefValuePathPieceLayout::readRecord(scratch, None, IID, None, None,
+                                             None);
         result = getIdentifier(IID);
         break;
       }
@@ -1423,8 +1428,9 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
         IdentifierID IID;
         IdentifierID privateDiscriminator;
         bool onlyInNominal = false;
+        bool importedFromClang = false;
         XRefTypePathPieceLayout::readRecord(scratch, IID, privateDiscriminator,
-                                            onlyInNominal);
+                                            onlyInNominal, importedFromClang);
         if (privateDiscriminator)
           goto giveUpFastPath;
 
@@ -1481,12 +1487,13 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
       Optional<swift::CtorInitializerKind> ctorInit;
       bool isType = false;
       bool inProtocolExt = false;
+      bool importedFromClang = false;
       bool isStatic = false;
       switch (recordID) {
       case XREF_TYPE_PATH_PIECE: {
         IdentifierID IID, discriminatorID;
         XRefTypePathPieceLayout::readRecord(scratch, IID, discriminatorID,
-                                            inProtocolExt);
+                                            inProtocolExt, importedFromClang);
         memberName = getDeclBaseName(IID);
         privateDiscriminator = getIdentifier(discriminatorID);
         isType = true;
@@ -1496,15 +1503,15 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
       case XREF_VALUE_PATH_PIECE: {
         IdentifierID IID;
         XRefValuePathPieceLayout::readRecord(scratch, TID, IID, inProtocolExt,
-                                             isStatic);
+                                             importedFromClang, isStatic);
         memberName = getDeclBaseName(IID);
         break;
       }
 
       case XREF_INITIALIZER_PATH_PIECE: {
         uint8_t kind;
         XRefInitializerPathPieceLayout::readRecord(scratch, TID, inProtocolExt,
-                                                   kind);
+                                                   importedFromClang, kind);
         memberName = DeclBaseName::createConstructor();
         ctorInit = getActualCtorInitializerKind(kind);
         break;
@@ -1557,8 +1564,8 @@ ModuleFile::resolveCrossReference(ModuleDecl *baseModule, uint32_t pathLen) {
         auto members = nominal->lookupDirect(memberName);
         values.append(members.begin(), members.end());
       }
-      filterValues(filterTy, M, genericSig, isType, inProtocolExt, isStatic,
-                   ctorInit, values);
+      filterValues(filterTy, M, genericSig, isType, inProtocolExt,
+                   importedFromClang, isStatic, ctorInit, values);
       break;
     }
 

lib/Serialization/Serialization.cpp

@@ -1902,7 +1902,8 @@ void Serializer::writeCrossReference(const DeclContext *DC, uint32_t pathLen) {
     XRefTypePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
                                         addDeclBaseNameRef(generic->getName()),
                                         addDeclBaseNameRef(discriminator),
-                                        false);
+                                        /*inProtocolExtension*/false,
+                                        generic->hasClangNode());
     break;
   }
 
@@ -1933,7 +1934,8 @@ void Serializer::writeCrossReference(const DeclContext *DC, uint32_t pathLen) {
     bool isProtocolExt = SD->getDeclContext()->getAsProtocolExtensionContext();
     XRefValuePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
                                          addTypeRef(ty), SUBSCRIPT_ID,
-                                         isProtocolExt, SD->isStatic());
+                                         isProtocolExt, SD->hasClangNode(),
+                                         SD->isStatic());
     break;
   }
 
@@ -1949,6 +1951,7 @@ void Serializer::writeCrossReference(const DeclContext *DC, uint32_t pathLen) {
       XRefValuePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
                                            addTypeRef(ty), nameID,
                                            isProtocolExt,
+                                           storage->hasClangNode(),
                                            storage->isStatic());
 
       abbrCode =
@@ -1973,6 +1976,7 @@ void Serializer::writeCrossReference(const DeclContext *DC, uint32_t pathLen) {
       XRefInitializerPathPieceLayout::emitRecord(
         Out, ScratchRecord, abbrCode, addTypeRef(ty),
         (bool)ctor->getDeclContext()->getAsProtocolExtensionContext(),
+        ctor->hasClangNode(),
         getStableCtorInitializerKind(ctor->getInitKind()));
       break;
     }
@@ -1982,7 +1986,7 @@ void Serializer::writeCrossReference(const DeclContext *DC, uint32_t pathLen) {
     XRefValuePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
                                          addTypeRef(ty),
                                          addDeclBaseNameRef(fn->getBaseName()),
-                                         isProtocolExt,
+                                         isProtocolExt, fn->hasClangNode(),
                                          fn->isStatic());
 
     if (fn->isOperator()) {
@@ -2062,7 +2066,7 @@ void Serializer::writeCrossReference(const Decl *D) {
     XRefTypePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
                                         addDeclBaseNameRef(type->getName()),
                                         addDeclBaseNameRef(discriminator),
-                                        isProtocolExt);
+                                        isProtocolExt, D->hasClangNode());
     return;
   }
 
@@ -2071,10 +2075,8 @@ void Serializer::writeCrossReference(const Decl *D) {
   abbrCode = DeclTypeAbbrCodes[XRefValuePathPieceLayout::Code];
   IdentifierID iid = addDeclBaseNameRef(val->getBaseName());
   XRefValuePathPieceLayout::emitRecord(Out, ScratchRecord, abbrCode,
-                                       addTypeRef(ty),
-                                       iid,
-                                       isProtocolExt,
-                                       val->isStatic());
+                                       addTypeRef(ty), iid, isProtocolExt,
+                                       D->hasClangNode(), val->isStatic());
 }
 
 /// Translate from the AST associativity enum to the Serialization enum

validation-test/Serialization/rdar40839486.swift

@@ -0,0 +1,18 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -emit-module-path %t/main4.swiftmodule -swift-version 4 %s
+// RUN: %target-build-swift -emit-module-path %t/main4_2.swiftmodule -swift-version 4.2 %s
+
+// REQUIRES: OS=macosx || OS=ios
+
+import CloudKit
+
+@available(macOS 10.10, iOS 8, *)
+extension CKRecord {
+  @inlinable public func testMethod() -> Any? {
+    return self.object(forKey: "abc" as CKRecord.FieldKey)
+  }
+
+  @inlinable public func testSubscript() -> Any? {
+    return self["abc" as CKRecord.FieldKey]
+  }
+}