Merge pull request #70468 from apple/egorzhdan/5.10-split-libcxx-fixes

🍒[cxx-interop] Fix fallout of splitting libc++ module into many top-level modules

Author: egorzhdan

include/swift/ClangImporter/ClangImporter.h

@@ -632,6 +632,11 @@ namespace importer {
 /// Returns true if the given module has a 'cplusplus' requirement.
 bool requiresCPlusPlus(const clang::Module *module);
 
+/// Returns true if the given module is one of the C++ standard library modules.
+/// This could be the top-level std module, or any of the libc++ split modules
+/// (std_vector, std_iosfwd, etc).
+bool isCxxStdModule(const clang::Module *module);
+
 /// Returns the pointee type if the given type is a C++ `const`
 /// reference type, `None` otherwise.
 llvm::Optional<clang::QualType>

lib/ClangImporter/ClangDerivedConformances.cpp

@@ -126,7 +126,11 @@ getIteratorCategoryDecl(const clang::CXXRecordDecl *clangDecl) {
   clang::IdentifierInfo *iteratorCategoryDeclName =
       &clangDecl->getASTContext().Idents.get("iterator_category");
   auto iteratorCategories = clangDecl->lookup(iteratorCategoryDeclName);
-  if (!iteratorCategories.isSingleResult())
+  // If this is a templated typedef, Clang might have instantiated several
+  // equivalent typedef decls. If they aren't equivalent, Clang has already
+  // complained about this. Let's assume that they are equivalent. (see
+  // filterNonConflictingPreviousTypedefDecls in clang/Sema/SemaDecl.cpp)
+  if (iteratorCategories.empty())
     return nullptr;
   auto iteratorCategory = iteratorCategories.front();
 

lib/ClangImporter/ClangImporter.cpp

@@ -2157,7 +2157,8 @@ ModuleDecl *ClangImporter::Implementation::loadModule(
   ASTContext &ctx = getNameImporter().getContext();
 
   // `CxxStdlib` is the only accepted spelling of the C++ stdlib module name.
-  if (path.front().Item.is("std"))
+  if (path.front().Item.is("std") ||
+      path.front().Item.str().starts_with("std_"))
     return nullptr;
   if (path.front().Item == ctx.Id_CxxStdlib) {
     ImportPath::Builder adjustedPath(ctx.getIdentifier("std"), importLoc);
@@ -3979,6 +3980,13 @@ ModuleDecl *ClangModuleUnit::getOverlayModule() const {
       ImportPath::Module::Builder builder(M->getName());
       (void) owner.loadModule(SourceLoc(), std::move(builder).get());
     }
+    // If this Clang module is a part of the C++ stdlib, and we haven't loaded
+    // the overlay for it so far, it is a split libc++ module (e.g. std_vector).
+    // Load the CxxStdlib overlay explicitly.
+    if (!overlay && importer::isCxxStdModule(clangModule)) {
+      ImportPath::Module::Builder builder(Ctx.Id_CxxStdlib);
+      overlay = owner.loadModule(SourceLoc(), std::move(builder).get());
+    }
     auto mutableThis = const_cast<ClangModuleUnit *>(this);
     mutableThis->overlayModule.setPointerAndInt(overlay, true);
   }
@@ -7464,7 +7472,7 @@ const clang::TypedefType *ClangImporter::getTypeDefForCXXCFOptionsDefinition(
 
 bool importer::requiresCPlusPlus(const clang::Module *module) {
   // The libc++ modulemap doesn't currently declare the requirement.
-  if (module->getTopLevelModuleName() == "std")
+  if (isCxxStdModule(module))
     return true;
 
   // Modulemaps often declare the requirement for the top-level module only.
@@ -7478,6 +7486,18 @@ bool importer::requiresCPlusPlus(const clang::Module *module) {
   });
 }
 
+bool importer::isCxxStdModule(const clang::Module *module) {
+  if (module->getTopLevelModuleName() == "std")
+    return true;
+  // In recent libc++ versions the module is split into multiple top-level
+  // modules (std_vector, std_utility, etc).
+  if (module->getTopLevelModule()->IsSystem &&
+      module->getTopLevelModuleName().starts_with("std_"))
+    return true;
+
+  return false;
+}
+
 llvm::Optional<clang::QualType>
 importer::getCxxReferencePointeeTypeOrNone(const clang::Type *type) {
   if (type->isReferenceType())

lib/ClangImporter/ImportDecl.cpp

@@ -3267,7 +3267,8 @@ namespace {
                     ->getTopLevelModule()
                     ->getFullModuleName() == n;
         };
-        if (topLevelModuleEq(decl, "std")) {
+        if ((decl->getOwningModule() &&
+             importer::isCxxStdModule(decl->getOwningModule()))) {
           if (isAlternativeCStdlibFunctionFromTextualHeader(decl)) {
             return nullptr;
           }

test/Interop/Cxx/stdlib/libcxx-module-interface.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-ide-test -print-module -module-to-print=CxxStdlib -source-filename=x -enable-experimental-cxx-interop -tools-directory=%llvm_obj_root/bin -module-cache-path %t | %FileCheck %s  -check-prefix=CHECK-STD
+// RUN: %target-swift-ide-test -print-module -module-to-print=CxxStdlib -source-filename=x -enable-experimental-cxx-interop -tools-directory=%llvm_obj_root/bin -module-cache-path %t -module-print-submodules | %FileCheck %s  -check-prefix=CHECK-STD-WITH-SUBMODULES
 // RUN: %target-swift-ide-test -print-module -module-to-print=CxxStdlib.iosfwd -source-filename=x -enable-experimental-cxx-interop -tools-directory=%llvm_obj_root/bin -module-cache-path %t | %FileCheck %s  -check-prefix=CHECK-IOSFWD
 // RUN: %target-swift-ide-test -print-module -module-to-print=CxxStdlib.string -source-filename=x -enable-experimental-cxx-interop -tools-directory=%llvm_obj_root/bin -module-cache-path %t | %FileCheck %s  -check-prefix=CHECK-STRING
 
@@ -8,6 +9,10 @@
 // CHECK-STD: import CxxStdlib.iosfwd
 // CHECK-STD: import CxxStdlib.string
 
+// CHECK-STD-WITH-SUBMODULES: enum std {
+// CHECK-STD-WITH-SUBMODULES: enum __1 {
+// CHECK-STD-WITH-SUBMODULES-NOT: enum std
+
 // CHECK-IOSFWD: enum std {
 // CHECK-IOSFWD:   enum __1 {
 // CHECK-IOSFWD:     struct basic_string<CChar, char_traits<CChar>, allocator<CChar>> : CxxRandomAccessCollection {
@@ -20,10 +25,12 @@
 // CHECK-IOSFWD:     typealias wstring = std.__1.basic_string<CWideChar, char_traits<CWideChar>, allocator<CWideChar>>
 // CHECK-IOSFWD:   }
 // CHECK-IOSFWD: }
+// CHECK-IOSFWD-NOT: enum std
 
 // CHECK-STRING: enum std {
 // CHECK-STRING:   enum __1 {
 // CHECK-STRING:     static func to_string(_ __val: Int32) -> std.__1.string
 // CHECK-STRING:     static func to_wstring(_ __val: Int32) -> std.__1.wstring
 // CHECK-STRING:   }
 // CHECK-STRING: }
+// CHECK-STRING-NOT: enum std

test/Interop/Cxx/stdlib/print-libcxx-module-interface.swift

@@ -8,7 +8,7 @@
 // REQUIRES: OS=macosx
 
 // CHECK: enum std {
-// CHECK-NEXT: enum __1 {
+// CHECK: enum __1 {
 
 // STRING: struct basic_string {