AST: Extend @_originallyDefinedIn to allow specifying module name for linker directive purposes

slavapestov · slavapestov · commit 0155b41b50e6 · 2025-03-24T17:56:45.000-04:00
The module name changes the symbol mangling, and also causes
TBDGen to emit linker directives. To separate out these two
behaviors, introduce a terrible hack. If the module name
contains a semicolon (`;`), the part before the semicolon
is the module name for mangling, and the part after the
semicolon is the module name for linker directives.

If there is no semicolon, both module names are identical,
and the behavior is the same as before.
diff --git a/include/swift/AST/Attr.h b/include/swift/AST/Attr.h
@@ -2050,17 +2050,29 @@ class ProjectedValuePropertyAttr : public DeclAttribute {
 class OriginallyDefinedInAttr: public DeclAttribute {
 public:
   OriginallyDefinedInAttr(SourceLoc AtLoc, SourceRange Range,
-                          StringRef OriginalModuleName, PlatformKind Platform,
+                          StringRef OriginalModuleName,
+                          PlatformKind Platform,
+                          const llvm::VersionTuple MovedVersion, bool Implicit);
+
+  OriginallyDefinedInAttr(SourceLoc AtLoc, SourceRange Range,
+                          StringRef ManglingModuleName,
+                          StringRef LinkerModuleName,
+                          PlatformKind Platform,
                           const llvm::VersionTuple MovedVersion, bool Implicit)
       : DeclAttribute(DeclAttrKind::OriginallyDefinedIn, AtLoc, Range,
                       Implicit),
-        OriginalModuleName(OriginalModuleName), Platform(Platform),
+        ManglingModuleName(ManglingModuleName),
+        LinkerModuleName(LinkerModuleName),
+        Platform(Platform),
         MovedVersion(MovedVersion) {}
 
   OriginallyDefinedInAttr *clone(ASTContext &C, bool implicit) const;
 
-  // The original module name.
-  const StringRef OriginalModuleName;
+  // The original module name for mangling.
+  const StringRef ManglingModuleName;
+
+  // The original module name for linker directives.
+  const StringRef LinkerModuleName;
 
   /// The platform of the symbol.
   const PlatformKind Platform;
@@ -2069,7 +2081,8 @@ class OriginallyDefinedInAttr: public DeclAttribute {
   const llvm::VersionTuple MovedVersion;
 
   struct ActiveVersion {
-    StringRef ModuleName;
+    StringRef ManglingModuleName;
+    StringRef LinkerModuleName;
     PlatformKind Platform;
     llvm::VersionTuple Version;
     bool ForTargetVariant = false;
@@ -2085,7 +2098,8 @@ class OriginallyDefinedInAttr: public DeclAttribute {
   /// Create a copy of this attribute.
   OriginallyDefinedInAttr *clone(ASTContext &ctx) const {
     return new (ctx) OriginallyDefinedInAttr(
-        AtLoc, Range, OriginalModuleName, Platform, MovedVersion, isImplicit());
+        AtLoc, Range, ManglingModuleName, LinkerModuleName,
+        Platform, MovedVersion, isImplicit());
   }
 };
 
diff --git a/lib/AST/ASTDumper.cpp b/lib/AST/ASTDumper.cpp
@@ -5214,7 +5214,8 @@ class PrintAttribute : public AttributeVisitor<PrintAttribute, void, Label>,
   void visitOriginallyDefinedInAttr(OriginallyDefinedInAttr *Attr,
                                     Label label) {
     printCommon(Attr, "originally_defined_in_attr", label);
-    printField(Attr->OriginalModuleName, Label::always("original_module"));
+    printField(Attr->ManglingModuleName, Label::always("mangling_module"));
+    printField(Attr->LinkerModuleName, Label::always("linker_module"));
     printField(Attr->Platform, Label::always("platform"));
     printFieldRaw([&](auto &out) { out << Attr->MovedVersion.getAsString(); },
                   Label::always("moved_version"));
diff --git a/lib/AST/ASTPrinter.cpp b/lib/AST/ASTPrinter.cpp
@@ -5986,7 +5986,7 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       for (auto attr: D->getAttrs().getAttributes<OriginallyDefinedInAttr>()) {
         Name = Mod->getASTContext()
           .getIdentifier(const_cast<OriginallyDefinedInAttr*>(attr)
-                         ->OriginalModuleName);
+                         ->ManglingModuleName);
         break;
       }
     }
diff --git a/lib/AST/Attr.cpp b/lib/AST/Attr.cpp
@@ -1175,8 +1175,12 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     Printer.printAttrName("@_originallyDefinedIn");
     Printer << "(module: ";
     auto Attr = cast<OriginallyDefinedInAttr>(this);
-    Printer << "\"" << Attr->OriginalModuleName << "\", ";
-    Printer << platformString(Attr->Platform) << " " <<
+    Printer << "\"" << Attr->ManglingModuleName;
+    ASSERT(!Attr->ManglingModuleName.empty());
+    ASSERT(!Attr->LinkerModuleName.empty());
+    if (Attr->LinkerModuleName != Attr->ManglingModuleName)
+      Printer << ";" << Attr->LinkerModuleName;
+    Printer << "\", " << platformString(Attr->Platform) << " " <<
       Attr->MovedVersion.getAsString();
     Printer << ")";
     break;
@@ -2235,12 +2239,39 @@ AvailableAttr *AvailableAttr::clone(ASTContext &C, bool implicit) const {
       implicit ? SourceRange() : ObsoletedRange, implicit, isSPI());
 }
 
+static StringRef getManglingModuleName(StringRef OriginalModuleName) {
+  auto index = OriginalModuleName.find(";");
+  return index == StringRef::npos
+      ? OriginalModuleName
+      : OriginalModuleName.slice(0, index);
+}
+
+static StringRef getLinkerModuleName(StringRef OriginalModuleName) {
+  auto index = OriginalModuleName.find(";");
+  return index == StringRef::npos
+      ? OriginalModuleName
+      : OriginalModuleName.slice(index + 1, OriginalModuleName.size());
+}
+
+OriginallyDefinedInAttr::OriginallyDefinedInAttr(
+    SourceLoc AtLoc, SourceRange Range,
+    StringRef OriginalModuleName,
+    PlatformKind Platform,
+    const llvm::VersionTuple MovedVersion, bool Implicit)
+  : DeclAttribute(DeclAttrKind::OriginallyDefinedIn, AtLoc, Range,
+                  Implicit),
+    ManglingModuleName(getManglingModuleName(OriginalModuleName)),
+    LinkerModuleName(getLinkerModuleName(OriginalModuleName)),
+    Platform(Platform),
+    MovedVersion(MovedVersion) {}
+
 std::optional<OriginallyDefinedInAttr::ActiveVersion>
 OriginallyDefinedInAttr::isActivePlatform(const ASTContext &ctx) const {
   OriginallyDefinedInAttr::ActiveVersion Result;
   Result.Platform = Platform;
   Result.Version = MovedVersion;
-  Result.ModuleName = OriginalModuleName;
+  Result.ManglingModuleName = ManglingModuleName;
+  Result.LinkerModuleName = LinkerModuleName;
   if (isPlatformActive(Platform, ctx.LangOpts, /*TargetVariant*/false)) {
     return Result;
   }
@@ -2260,7 +2291,7 @@ OriginallyDefinedInAttr *OriginallyDefinedInAttr::clone(ASTContext &C,
                                                         bool implicit) const {
   return new (C) OriginallyDefinedInAttr(
       implicit ? SourceLoc() : AtLoc, implicit ? SourceRange() : getRange(),
-      OriginalModuleName, Platform, MovedVersion, implicit);
+      ManglingModuleName, LinkerModuleName, Platform, MovedVersion, implicit);
 }
 
 bool AvailableAttr::isUnconditionallyUnavailable() const {
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
@@ -1101,7 +1101,7 @@ StringRef Decl::getAlternateModuleName() const {
   for (auto *Att: Attrs) {
     if (auto *OD = dyn_cast<OriginallyDefinedInAttr>(Att)) {
       if (!OD->isInvalid() && OD->isActivePlatform(getASTContext())) {
-        return OD->OriginalModuleName;
+        return OD->ManglingModuleName;
       }
     }
   }
diff --git a/lib/IRGen/IRGenDebugInfo.cpp b/lib/IRGen/IRGenDebugInfo.cpp
@@ -2541,10 +2541,10 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
       if (auto Attribute =
               ND->getAttrs().getAttribute<OriginallyDefinedInAttr>()) {
         auto Identifier = IGM.getSILModule().getASTContext().getIdentifier(
-            Attribute->OriginalModuleName);
+            Attribute->ManglingModuleName);
         void *Key = (void *)Identifier.get();
         Scope =
-            getOrCreateModule(Key, TheCU, Attribute->OriginalModuleName, {});
+            getOrCreateModule(Key, TheCU, Attribute->ManglingModuleName, {});
       } else {
         Context = ND->getParent();
       }
diff --git a/lib/IRGen/TBDGen.cpp b/lib/IRGen/TBDGen.cpp
@@ -88,15 +88,18 @@ void TBDGenVisitor::addSymbolInternal(StringRef name, EncodeKind kind,
 
 static std::vector<OriginallyDefinedInAttr::ActiveVersion>
 getAllMovedPlatformVersions(Decl *D) {
+  StringRef Name = D->getDeclContext()->getParentModule()->getName().str();
+
   std::vector<OriginallyDefinedInAttr::ActiveVersion> Results;
   for (auto *attr: D->getAttrs()) {
     if (auto *ODA = dyn_cast<OriginallyDefinedInAttr>(attr)) {
       auto Active = ODA->isActivePlatform(D->getASTContext());
-      if (Active.has_value()) {
+      if (Active.has_value() && Active->LinkerModuleName != Name) {
         Results.push_back(*Active);
       }
     }
   }
+
   return Results;
 }
 
@@ -324,16 +327,16 @@ void TBDGenVisitor::addLinkerDirectiveSymbolsLdPrevious(
     if (*IntroVer >= Ver.Version)
       continue;
     auto PlatformNumber = getLinkerPlatformId(Ver, Ctx);
-    auto It = previousInstallNameMap->find(Ver.ModuleName.str());
+    auto It = previousInstallNameMap->find(Ver.LinkerModuleName.str());
     if (It == previousInstallNameMap->end()) {
       Ctx.Diags.diagnose(SourceLoc(), diag::cannot_find_install_name,
-                         Ver.ModuleName, getLinkerPlatformName(Ver, Ctx));
+                         Ver.LinkerModuleName, getLinkerPlatformName(Ver, Ctx));
       continue;
     }
     auto InstallName = It->second.getInstallName(PlatformNumber);
     if (InstallName.empty()) {
       Ctx.Diags.diagnose(SourceLoc(), diag::cannot_find_install_name,
-                         Ver.ModuleName, getLinkerPlatformName(Ver, Ctx));
+                         Ver.LinkerModuleName, getLinkerPlatformName(Ver, Ctx));
       continue;
     }
     llvm::SmallString<64> Buffer;
diff --git a/lib/Serialization/Deserialization.cpp b/lib/Serialization/Deserialization.cpp
@@ -6043,11 +6043,23 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
            Platform);
         llvm::VersionTuple MovedVer;
         DECODE_VER_TUPLE(MovedVer)
-        auto ModuleNameEnd = blobData.find('\0');
-        assert(ModuleNameEnd != StringRef::npos);
-        auto ModuleName = blobData.slice(0, ModuleNameEnd);
+
+        auto ManglingModuleNameEnd = blobData.find('\0');
+        assert(ManglingModuleNameEnd != StringRef::npos);
+        auto ManglingModuleName = blobData.slice(0, ManglingModuleNameEnd);
+
+        blobData = blobData.slice(ManglingModuleNameEnd + 1, blobData.size());
+
+        auto LinkerModuleNameEnd = blobData.find('\0');
+        assert(LinkerModuleNameEnd != StringRef::npos);
+        auto LinkerModuleName = blobData.slice(0, LinkerModuleNameEnd);
+
+        ASSERT(!ManglingModuleName.empty());
+        ASSERT(!LinkerModuleName.empty());
+
         Attr = new (ctx) OriginallyDefinedInAttr(SourceLoc(), SourceRange(),
-                                                 ModuleName,
+                                                 ManglingModuleName,
+                                                 LinkerModuleName,
                                                  (PlatformKind)Platform,
                                                  MovedVer,
                                                  isImplicit);
diff --git a/lib/Serialization/ModuleFormat.h b/lib/Serialization/ModuleFormat.h
@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_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 SWIFTMODULE_VERSION_MINOR = 928; // abstract conforming type
+const uint16_t SWIFTMODULE_VERSION_MINOR = 929; // OriginallyDefinedInAttr::LinkerModuleName
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
diff --git a/lib/Serialization/Serialization.cpp b/lib/Serialization/Serialization.cpp
@@ -3094,7 +3094,9 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
           Moved, std::optional<llvm::VersionTuple>(theAttr->MovedVersion));
       auto abbrCode = S.DeclTypeAbbrCodes[OriginallyDefinedInDeclAttrLayout::Code];
       llvm::SmallString<32> blob;
-      blob.append(theAttr->OriginalModuleName.str());
+      blob.append(theAttr->ManglingModuleName.str());
+      blob.push_back('\0');
+      blob.append(theAttr->LinkerModuleName.str());
       blob.push_back('\0');
       OriginallyDefinedInDeclAttrLayout::emitRecord(
           S.Out, S.ScratchRecord, abbrCode,
diff --git a/test/IRGen/Inputs/backward_deploy_nominal.json b/test/IRGen/Inputs/backward_deploy_nominal.json
@@ -0,0 +1,6 @@
+[
+  {
+    "module": "Compatibility59",
+    "install_name": "libswiftCompatibility59.dylib"
+  }
+]
diff --git a/test/IRGen/backward_deploy_nominal.swift b/test/IRGen/backward_deploy_nominal.swift
@@ -0,0 +1,24 @@
+// RUN: %target-swift-frontend -emit-ir -parse-as-library -parse-stdlib %s -module-name Swift -previous-module-installname-map-file %S/Inputs/backward_deploy_nominal.json | %FileCheck %s
+// RUN: %target-swift-frontend -emit-ir -parse-as-library -parse-stdlib %s -module-name Swift -previous-module-installname-map-file %S/Inputs/backward_deploy_nominal.json | %FileCheck %s --check-prefix=ALSO
+
+// RUN: %target-swift-frontend -emit-ir -parse-as-library -parse-stdlib %s -module-name Compatibility59 -module-abi-name Swift | %FileCheck %s --check-prefix=CHECK-SHIM
+// RUN: %target-swift-frontend -emit-ir -parse-as-library -parse-stdlib %s -module-name Compatibility59 -module-abi-name Swift | %FileCheck %s --check-prefix=ALSO-SHIM
+
+// REQUIRES: OS=macosx
+
+// Let's just pretend...
+@available(macOS 13, *)
+@_originallyDefinedIn(module: "Swift;Compatibility59", macOS 14)
+public struct Fridge<Contents> {}
+
+// Ultimately, both modules must export the same nominal type descriptor.
+// CHECK-DAG: @"$ss6FridgeVMn" =
+// CHECK-SHIM-DAG: @"$ss6FridgeVMn" =
+
+// The home module also has linker directives.
+// CHECK-DAG: @"\01$ld$previous$libswiftCompatibility59.dylib$$1$13.0$14.0$_$ss6FridgeVMn$" =
+// ALSO-NOT: $ld$hide$
+
+// The compatibility shim does not have any linker directives.
+// ALSO-SHIM-NOT: $ld$hide$
+// ALSO-SHIM-NOT: $ld$previous$

Original file line number	Diff line number	Diff line change
`@@ -5986,7 +5986,7 @@ class TypePrinter : public TypeVisitor<TypePrinter> {`
`5986`	`5986`	`for (auto attr: D->getAttrs().getAttributes<OriginallyDefinedInAttr>()) {`
`5987`	`5987`	`Name = Mod->getASTContext()`
`5988`	`5988`	`.getIdentifier(const_cast<OriginallyDefinedInAttr*>(attr)`
`5989`		`- ->OriginalModuleName);`
	`5989`	`+ ->ManglingModuleName);`
`5990`	`5990`	`break;`
`5991`	`5991`	`}`
`5992`	`5992`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1101,7 +1101,7 @@ StringRef Decl::getAlternateModuleName() const {`
`1101`	`1101`	`for (auto *Att: Attrs) {`
`1102`	`1102`	`if (auto *OD = dyn_cast<OriginallyDefinedInAttr>(Att)) {`
`1103`	`1103`	`if (!OD->isInvalid() && OD->isActivePlatform(getASTContext())) {`
`1104`		`- return OD->OriginalModuleName;`
	`1104`	`+ return OD->ManglingModuleName;`
`1105`	`1105`	`}`
`1106`	`1106`	`}`
`1107`	`1107`	`}`