Serialization: Remove obsolete 'HasUnderlyingModule' hack

Author: slavapestov

include/swift/Serialization/ModuleFile.h

@@ -156,8 +156,6 @@ class ModuleFile
     bool isHeader() const { return IsHeader; }
     bool isScoped() const { return IsScoped; }
 
-    void forceExported() { IsExported = true; }
-
     std::string getPrettyPrintedPath() const;
   };
 
@@ -399,12 +397,6 @@ class ModuleFile
     /// Whether this module file comes from a framework.
     unsigned IsFramework : 1;
 
-    /// THIS SETTING IS OBSOLETE BUT IS STILL USED BY OLDER MODULES.
-    ///
-    /// Whether this module has a shadowed module that's part of its public
-    /// interface.
-    unsigned HasUnderlyingModule : 1;
-
     /// Whether or not ImportDecls is valid.
     unsigned ComputedImportDecls : 1;
 

include/swift/Serialization/ModuleFormat.h

@@ -583,7 +583,7 @@ namespace input_block {
     LINK_LIBRARY,
     IMPORTED_HEADER,
     IMPORTED_HEADER_CONTENTS,
-    MODULE_FLAGS,
+    MODULE_FLAGS, // [unused]
     SEARCH_PATH
   };
 
@@ -616,11 +616,6 @@ namespace input_block {
     BCBlob
   >;
 
-  using ModuleFlagsLayout = BCRecordLayout<
-    MODULE_FLAGS,
-    BCFixed<1> // has underlying module? [[UNUSED]]
-  >;
-
   using SearchPathLayout = BCRecordLayout<
     SEARCH_PATH,
     BCFixed<1>, // framework?

lib/Serialization/ModuleFile.cpp

@@ -1128,7 +1128,6 @@ ModuleFile::ModuleFile(
       }
 
       cursor.EnterSubBlock(INPUT_BLOCK_ID);
-      bool seenFlags = false;
 
       auto next = cursor.advance();
       while (next.Kind == llvm::BitstreamEntry::Record) {
@@ -1169,15 +1168,6 @@ ModuleFile::ModuleFile(
           importedHeaderInfo.contents = blobData;
           break;
         }
-        case input_block::MODULE_FLAGS: {
-          assert(!seenFlags && "only one flags record allowed");
-          seenFlags = true;
-          bool hasUnderlyingModule;
-          input_block::ModuleFlagsLayout::readRecord(scratch,
-                                                     hasUnderlyingModule);
-          Bits.HasUnderlyingModule = hasUnderlyingModule;
-          break;
-        }
         case input_block::SEARCH_PATH: {
           bool isFramework;
           bool isSystem;
@@ -1433,11 +1423,6 @@ Status ModuleFile::associateWithFileContext(FileUnit *file,
       continue;
     }
 
-    // This is for backwards-compatibility with modules that still rely on the
-    // "HasUnderlyingModule" flag.
-    if (Bits.HasUnderlyingModule && module == ShadowedModule)
-      dependency.forceExported();
-
     if (scopePath.empty()) {
       dependency.Import = { {}, module };
     } else {

lib/Serialization/Serialization.cpp

@@ -1043,7 +1043,6 @@ void Serializer::writeInputBlock(const SerializationOptions &options) {
   input_block::LinkLibraryLayout LinkLibrary(Out);
   input_block::ImportedHeaderLayout ImportedHeader(Out);
   input_block::ImportedHeaderContentsLayout ImportedHeaderContents(Out);
-  input_block::ModuleFlagsLayout ModuleFlags(Out);
   input_block::SearchPathLayout SearchPath(Out);
 
   if (options.SerializeOptionsForDebugging) {