Display the pointer value in the libstdc++ unique_ptr summary

[labath]

Summary

r284830 added a summary provider for unique_ptr in libstdc++, whose value printed
the value of the pointee. This is a bit unintuitive as it becomes unobvious that
the value actually is a pointer, and we lose the way to actually obtain the
pointer value.

Change that to print the pointer value instead. The pointee value can still be
obtained through the synthetic children.

[granata.enrico]

Make what you will of my suggestion above, but in general the reasoning looks good

source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

129 ↗

(On Diff #77202)

This is very nitpick-y but why not

lldb::addr_t ptr_value = m_ptr_obj->GetValueAsUnsigned(LLDB_INVALID_ADDRESS)
switch (ptr_value) {

case 0: stream.Printf("nullptr"); break;
case LLDB_INVALID_ADDRESS: return false;
default: stream.Printf("0x%" PRIx64, ptr_value); break;

}

modulo clang-formatting the above, of course.

[labath]

source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

129 ↗

(On Diff #77202)

I've changed this to:

uint64_t ptr_value = m_ptr_obj->GetValueAsUnsigned(0, &success);
if (!success)
  return false;
if (ptr_value == 0)
  stream.Printf("nullptr");
else
  stream.Printf("0x%" PRIx64, ptr_value);

This should address the issue of not printing a bogus value if we fail to read the value, but avoid the case where the pointer value *is* 0xffff.. (which it can legitimately be, e.g. with custom deleters, or if the inferior corrupts it's memory).
At that point, the switch is not necessary.

[granata.enrico]

Makes sense. Feel free to commit.

lldb/trunk/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py

def test_with_run_command(self):
         # The stop reason of the thread should be breakpoint.
         self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
                     substrs=['stopped', 'stop reason = breakpoint'])
 
         frame = self.frame()
         self.assertTrue(frame.IsValid())
 
         self.expect("frame variable nup", substrs=['nup = nullptr'])
-        self.expect("frame variable iup", substrs=['iup = 123', 'object = 123'])
-        self.expect("frame variable sup", substrs=['sup = "foobar"', 'object = "foobar"'])
+        self.expect("frame variable iup", substrs=['iup = 0x', 'object = 123'])
+        self.expect("frame variable sup", substrs=['sup = 0x', 'object = "foobar"'])
 
         self.expect("frame variable ndp", substrs=['ndp = nullptr'])
-        self.expect("frame variable idp", substrs=['idp = 456', 'object = 456', 'deleter = ', 'a = 1', 'b = 2'])
-        self.expect("frame variable sdp", substrs=['sdp = "baz"', 'object = "baz"', 'deleter = ', 'a = 3', 'b = 4'])
+        self.expect("frame variable idp", substrs=['idp = 0x', 'object = 456', 'deleter = ', 'a = 1', 'b = 2'])
+        self.expect("frame variable sdp", substrs=['sdp = 0x', 'object = "baz"', 'deleter = ', 'a = 3', 'b = 4'])
         
         self.assertEqual(123, frame.GetValueForVariablePath("iup.object").GetValueAsUnsigned())
         self.assertFalse(frame.GetValueForVariablePath("iup.deleter").IsValid())
 
         self.assertEqual('"foobar"', frame.GetValueForVariablePath("sup.object").GetSummary())
         self.assertFalse(frame.GetValueForVariablePath("sup.deleter").IsValid())
 
         self.assertEqual(456, frame.GetValueForVariablePath("idp.object").GetValueAsUnsigned())

lldb/trunk/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

size_t LibStdcppUniquePtrSyntheticFrontEnd::GetIndexOfChildWithName(
   return UINT32_MAX;
 }
 
 bool LibStdcppUniquePtrSyntheticFrontEnd::GetSummary(
     Stream &stream, const TypeSummaryOptions &options) {
   if (!m_ptr_obj)
     return false;
 
-  if (m_ptr_obj->GetValueAsUnsigned(0) == 0) {
+  bool success;
+  uint64_t ptr_value = m_ptr_obj->GetValueAsUnsigned(0, &success);
+  if (!success)
+    return false;
+  if (ptr_value == 0)
     stream.Printf("nullptr");
-  } else {
-    Error error;
-    bool print_pointee = false;
-    if (m_obj_obj) {
-      if (m_obj_obj->DumpPrintableRepresentation(
-              stream, ValueObject::eValueObjectRepresentationStyleSummary,
-              lldb::eFormatInvalid,
-              ValueObject::PrintableRepresentationSpecialCases::eDisable,
-              false)) {
-        print_pointee = true;
-      }
-    }
-    if (!print_pointee)
-      stream.Printf("ptr = 0x%" PRIx64, m_ptr_obj->GetValueAsUnsigned(0));
-  }
+  else
+    stream.Printf("0x%" PRIx64, ptr_value);
   return true;
 }
 
 SyntheticChildrenFrontEnd *
 lldb_private::formatters::LibStdcppUniquePtrSyntheticFrontEndCreator(
     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
   return (valobj_sp ? new LibStdcppUniquePtrSyntheticFrontEnd(valobj_sp)
                     : nullptr);
 }
 
 bool lldb_private::formatters::LibStdcppUniquePointerSummaryProvider(
     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
   LibStdcppUniquePtrSyntheticFrontEnd formatter(valobj.GetSP());
   return formatter.GetSummary(stream, options);
 }