[wip][cxx-interop] Start fixing issue with layout of FRTs that contain base classes or un-importable memebers.

Author: zoecarver

lib/IRGen/GenClass.cpp

@@ -16,6 +16,9 @@
 
 #include "GenClass.h"
 
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/RecordLayout.h"
 #include "swift/ABI/Class.h"
 #include "swift/ABI/MetadataValues.h"
 #include "swift/AST/ASTContext.h"
@@ -281,6 +284,42 @@ namespace {
                                superclass);
     }
 
+    void maybeAddCxxRecordBases(ClassDecl *cd) {
+      auto cxxRecord = dyn_cast_or_null<clang::CXXRecordDecl>(cd->getClangDecl());
+      if (!cxxRecord)
+        return;
+
+      auto &layout = cxxRecord->getASTContext().getASTRecordLayout(cxxRecord);
+
+      for (auto base : cxxRecord->bases()) {
+        if (base.isVirtual())
+          continue;
+
+        auto baseType = base.getType().getCanonicalType();
+
+        auto baseRecord = cast<clang::RecordType>(baseType)->getDecl();
+        auto baseCxxRecord = cast<clang::CXXRecordDecl>(baseRecord);
+
+        if (baseCxxRecord->isEmpty())
+          continue;
+
+        auto offset = Size(layout.getBaseClassOffset(baseCxxRecord).getQuantity());
+        auto size = Size(cxxRecord->getASTContext().getTypeSizeInChars(baseType).getQuantity());
+
+        if (offset != CurSize) {
+          assert(offset > CurSize);
+          auto paddingSize = offset - CurSize;
+          auto &opaqueTI = IGM.getOpaqueStorageTypeInfo(paddingSize, Alignment(1));
+          auto element = ElementLayout::getIncomplete(opaqueTI);
+          addField(element, LayoutStrategy::Universal);
+        }
+
+        auto &opaqueTI = IGM.getOpaqueStorageTypeInfo(size, Alignment(1));
+        auto element = ElementLayout::getIncomplete(opaqueTI);
+        addField(element, LayoutStrategy::Universal);
+      }
+    }
+
     void addDirectFieldsFromClass(ClassDecl *rootClass, SILType rootClassType,
                                   ClassDecl *theClass, SILType classType,
                                   bool superclass) {
@@ -290,6 +329,8 @@ namespace {
                                                ->getRecursiveProperties()
                                                .hasUnboundGeneric());
 
+      maybeAddCxxRecordBases(theClass);
+
       forEachField(IGM, theClass, [&](Field field) {
         // Ignore missing properties here; we should have flagged these
         // with the classHasIncompleteLayout call above.