[Reflection] Fix the computation of boundaries in getFieldName().

Author: Davide Italiano

include/swift/Reflection/Records.h

@@ -87,9 +87,10 @@ class FieldRecord {
 
   StringRef getFieldName(uintptr_t Offset, uintptr_t Low,
                          uintptr_t High) const {
-    if (Offset < Low || Offset > High)
+    uintptr_t nameAddr = (uintptr_t)FieldName.get() + Offset;
+    if (nameAddr < Low || nameAddr > High)
       return "";
-    return (const char *)((uintptr_t)FieldName.get() + Offset);
+    return (const char *)nameAddr;
   }
 
   bool isIndirectCase() const {

stdlib/public/Reflection/TypeRefBuilder.cpp

@@ -194,8 +194,8 @@ bool TypeRefBuilder::getFieldTypeRefs(
                        - FD.second->TypeReference.SectionOffset;
     auto FieldOffset = FD.second->Field.SectionOffset
                      - FD.second->ReflectionString.SectionOffset;
-    auto Low = FD.second->ReflectionString.SectionOffset;
-    auto High = FD.second->ReflectionString.Metadata.size();
+    auto Low = (uintptr_t)(FD.second->ReflectionString.Metadata.startAddress());
+    auto High = (uintptr_t)(FD.second->ReflectionString.Metadata.endAddress());
     auto FieldName = Field.getFieldName(FieldOffset, Low, High);
 
     // Empty cases of enums do not have a type
@@ -341,8 +341,8 @@ void TypeRefBuilder::dumpFieldSection(std::ostream &OS) {
         OS << '-';
       OS << '\n';
       for (auto &field : descriptor) {
-        auto Low = sections.ReflectionString.SectionOffset;
-        auto High = sections.ReflectionString.Metadata.size();
+        auto Low = (uintptr_t)sections.ReflectionString.Metadata.startAddress();
+        auto High = (uintptr_t)sections.ReflectionString.Metadata.endAddress();
         OS << std::string(field.getFieldName(NameOffset, Low, High).begin(),
                           field.getFieldName(NameOffset, Low, High).end());
         if (field.hasMangledTypeName()) {

stdlib/public/runtime/ReflectionMirror.mm

@@ -328,7 +328,7 @@ static bool _shouldReportMissingReflectionMetadataWarnings() {
   const FieldDescriptor &descriptor = *fields;
   auto &field = descriptor.getFields()[index];
   // Bounds are always valid as the offset is constant.
-  auto name = field.getFieldName(0, 0, 1);
+  auto name = field.getFieldName(0, 0, std::numeric_limits<uint64_t>::max());
 
   // Enum cases don't always have types.
   if (!field.hasMangledTypeName())