Clang importer: start computing the effective lookup context with the name.

This places enumerators that will become either cases of a Swift enum
or options in a Swift option into the context of the C enum type for
the name lookup table.

Author: DougGregor

lib/ClangImporter/ClangImporter.cpp

@@ -706,10 +706,8 @@ void ClangImporter::Implementation::addEntryToLookupTable(
        SwiftLookupTable &table, clang::NamedDecl *named)
 {
   // If we have a name to import as, add this entry to the table.
-  if (DeclName name = importFullName(named)) {
-    clang::DeclContext *effectiveContext
-      = named->getDeclContext()->getRedeclContext() ->getPrimaryContext();
-
+  clang::DeclContext *effectiveContext;
+  if (DeclName name = importFullName(named, nullptr, &effectiveContext)) {
     table.addEntry(name, named, effectiveContext);
   }
 
@@ -1353,15 +1351,46 @@ static DeclName parseDeclName(ASTContext &ctx, StringRef Name) {
 
 DeclName ClangImporter::Implementation::importFullName(
            const clang::NamedDecl *D,
-           bool &hasCustomName) {
+           bool *hasCustomName,
+           clang::DeclContext **effectiveContext) {
+  // Compute the effective context, if requested.
+  if (effectiveContext) {
+    auto dc = const_cast<clang::DeclContext *>(D->getDeclContext());
+
+    // Enumerators can end up within their enclosing enum or in the global
+    // scope, depending how their enclosing enumeration is imported.
+    if (isa<clang::EnumConstantDecl>(D)) {
+      auto enumDecl = cast<clang::EnumDecl>(dc);
+      switch (classifyEnum(enumDecl)) {
+      case EnumKind::Enum:
+      case EnumKind::Options:
+        // Enums are mapped to Swift enums, Options to Swift option sets.
+        *effectiveContext = enumDecl;
+        break;
+
+      case EnumKind::Constants:
+      case EnumKind::Unknown:
+        // The enum constant goes into the redeclaration context of the
+        // enum.
+        *effectiveContext = enumDecl->getRedeclContext();
+        break;
+      }
+    } else {
+      // Everything else goes into its redeclaration context.
+      *effectiveContext = dc->getRedeclContext();
+    }
+  }
+
   // If we have a swift_name attribute, use that.
   if (auto *nameAttr = D->getAttr<clang::SwiftNameAttr>()) {
-    hasCustomName = true;
+    if (hasCustomName)
+      *hasCustomName = true;
     return parseDeclName(SwiftContext, nameAttr->getName());
   }
 
   // We don't have a customized name.
-  hasCustomName = false;
+  if (hasCustomName)
+    *hasCustomName = false;
 
   // For empty names, there is nothing to do.
   if (D->getDeclName().isEmpty()) return { };

lib/ClangImporter/ImportDecl.cpp

@@ -2720,7 +2720,7 @@ namespace {
 
       // Determine the name of the function.
       bool hasCustomName;
-      DeclName name = Impl.importFullName(decl, hasCustomName);
+      DeclName name = Impl.importFullName(decl, &hasCustomName);
       if (!name)
         return nullptr;
 
@@ -3014,7 +3014,7 @@ namespace {
       switch (Impl.getFactoryAsInit(objcClass, decl)) {
       case FactoryAsInitKind::AsInitializer:
         if (decl->hasAttr<clang::SwiftNameAttr>()) {
-          initName = Impl.importFullName(decl, hasCustomName);
+          initName = Impl.importFullName(decl, &hasCustomName);
           break;
         }
         // FIXME: We probably should stop using this codepath. It won't ever
@@ -3126,7 +3126,7 @@ namespace {
       bool hasCustomName;
       if (auto *customNameAttr = decl->getAttr<clang::SwiftNameAttr>()) {
         if (!customNameAttr->getName().startswith("init(")) {
-          name = Impl.importFullName(decl, hasCustomName);
+          name = Impl.importFullName(decl, &hasCustomName);
         }
       }
       if (!name) {

lib/ClangImporter/ImporterImpl.h

@@ -726,17 +726,19 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   ///
   /// Note that this may result in a name very different from the Clang name,
   /// so it should not be used when referencing Clang symbols.
-  DeclName importFullName(const clang::NamedDecl *D) {
-    bool hasCustomName;
-    return importFullName(D, hasCustomName);
-  }
-
-  /// Imports the full name of the given Clang declaration into Swift.
   ///
-  /// Note that this may result in a name very different from the Clang name,
-  /// so it should not be used when referencing Clang symbols.
+  /// \param D The Clang declaration whose name should be imported.
+  ///
+  /// \param hasCustomName If non-null, will be set to indicate whether the
+  /// name was provided directly via a C swift_name attribute.
+  ///
+  /// \param effectiveContext If non-null, will be set to the effective
+  /// Clang declaration context in which the declaration will be imported.
+  /// This can differ from D's redeclaration context when the Clang importer
+  /// introduces nesting, e.g., for enumerators within an NS_ENUM.
   DeclName importFullName(const clang::NamedDecl *D,
-                          bool &hasCustomName);
+                          bool *hasCustomName = nullptr,
+                          clang::DeclContext **effectiveContext = nullptr);
 
   /// Imports the name of the given Clang decl into Swift.
   ///

lib/ClangImporter/SwiftLookupTable.cpp

@@ -53,8 +53,7 @@ static bool matchesExistingDecl(clang::Decl *decl, clang::Decl *existingDecl) {
 
 void SwiftLookupTable::addEntry(DeclName name, clang::NamedDecl *decl,
                                 clang::DeclContext *effectiveContext) {
-  clang::DeclContext *context
-    = decl->getDeclContext()->getRedeclContext()->getPrimaryContext();
+  clang::DeclContext *context = effectiveContext->getPrimaryContext();
 
   // First, check whether there is already a full name entry.
   auto knownFull = FullNameTable.find(name);

test/IDE/dump_swift_lookup_tables.swift

@@ -24,13 +24,13 @@
 // CHECK-NEXT:   Point:
 // CHECK-NEXT:     TU: SNPoint
 // CHECK-NEXT:   Rouge:
-// CHECK-NEXT:     TU: SNColorRed
+// CHECK-NEXT:     SNColorChoice: SNColorRed
 // CHECK-NEXT:   SNColorBlue:
-// CHECK-NEXT:     TU: SNColorBlue
+// CHECK-NEXT:     SNColorChoice: SNColorBlue
 // CHECK-NEXT:   SNColorChoice:
 // CHECK-NEXT:     TU: SNColorChoice, SNColorChoice
 // CHECK-NEXT:   SNColorGreen:
-// CHECK-NEXT:     TU: SNColorGreen
+// CHECK-NEXT:     SNColorChoice: SNColorGreen
 // CHECK-NEXT:   SomeStruct:
 // CHECK-NEXT:     TU: SNSomeStruct
 // CHECK-NEXT:   __SNTransposeInPlace:

tools/swift-ide-test/swift-ide-test.cpp

@@ -953,7 +953,6 @@ static int doDumpAPI(const CompilerInvocation &InitInvok,
 
 static int doDumpImporterLookupTables(const CompilerInvocation &InitInvok,
                                       StringRef SourceFilename) {
-  auto &FEOpts = InitInvok.getFrontendOptions();
   if (options::ImportObjCHeader.empty()) {
     llvm::errs() << "implicit header required\n";
     llvm::cl::PrintHelpMessage();