Don't fallback to the display name. Assume the info is opacetic.

Author: JDevlieghere

lldb/include/lldb/Core/Mangled.h

@@ -291,8 +291,7 @@ class Mangled {
   /// demangled name.
   ///
   /// For a demangled name like "ns::MyClass<int>::templateFunc", this returns
-  /// just "templateFunc". If the demangled name is not available or the
-  /// basename range is invalid, this falls back to GetDisplayDemangledName().
+  /// just "templateFunc".
   ///
   /// \return
   ///     A ConstString containing the basename, or nullptr if computation

lldb/source/Core/Mangled.cpp

@@ -560,17 +560,14 @@ void Mangled::Encode(DataEncoder &file, ConstStringTable &strtab) const {
 ConstString Mangled::GetBaseName() const {
   const auto &demangled_info = GetDemangledInfo();
   if (!demangled_info.has_value())
-    return GetDisplayDemangledName();
+    return {};
 
   ConstString demangled_name = GetDemangledName();
   if (!demangled_name)
-    return GetDisplayDemangledName();
+    return {};
 
   const char *name_str = demangled_name.AsCString();
   const auto &range = demangled_info->BasenameRange;
-  if (range.first >= range.second || range.second > strlen(name_str))
-    return ConstString();
-
   return ConstString(
       llvm::StringRef(name_str + range.first, range.second - range.first));
 }