[lldb][DataFormatter] Format libstdc++ unique_ptr like we do libc++

The only difference is that with libc++ the summary string contains the
derefernced pointer value. With libstdc++ we currently display the
pointer itself, which seems redundant. E.g.,
```
(std::unique_ptr<int>) iup = 0x55555556d2b0 {
  pointer = 0x000055555556d2b0
}
(std::unique_ptr<std::basic_string<char> >) sup = 0x55555556d2d0 {
  pointer = "foobar"
}
```

This patch moves the logic into a common helper that's shared between
the libc++ and libstdc++ formatters.

Author: Michael137

lldb/include/lldb/DataFormatters/FormattersHelpers.h

@@ -55,6 +55,12 @@ void AddFilter(TypeCategoryImpl::SharedPointer category_sp,
 
 std::optional<size_t> ExtractIndexFromString(const char *item_name);
 
+/// Returns \c false if the smart pointer formatters shouldn't continue
+/// formatting the rest of the object. Currently this is the case when the
+/// pointer is a nullptr.
+bool DumpCxxSmartPtrPointerSummary(Stream &stream, ValueObject &ptr,
+                                   const TypeSummaryOptions &options);
+
 Address GetArrayAddressOrPointerValue(ValueObject &valobj);
 
 time_t GetOSXEpoch();

lldb/source/DataFormatters/FormattersHelpers.cpp

@@ -126,3 +126,25 @@ lldb_private::formatters::GetArrayAddressOrPointerValue(ValueObject &valobj) {
 
   return data_addr.address;
 }
+
+bool lldb_private::formatters::DumpCxxSmartPtrPointerSummary(
+    Stream &stream, ValueObject &ptr, const TypeSummaryOptions &options) {
+  if (ptr.GetValueAsUnsigned(0) == 0) {
+    stream.Printf("nullptr");
+    return true;
+  }
+
+  Status error;
+  ValueObjectSP pointee_sp = ptr.Dereference(error);
+  // FIXME: should we be handling this as an error?
+  if (!pointee_sp || !error.Success())
+    return false;
+
+  if (!pointee_sp->DumpPrintableRepresentation(
+          stream, ValueObject::eValueObjectRepresentationStyleSummary,
+          lldb::eFormatInvalid,
+          ValueObject::PrintableRepresentationSpecialCases::eDisable, false))
+    stream.Printf("ptr = 0x%" PRIx64, ptr.GetValueAsUnsigned(0));
+
+  return false;
+}

lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp

@@ -166,24 +166,8 @@ bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
   if (!ptr_sp)
     return false;
 
-  if (ptr_sp->GetValueAsUnsigned(0) == 0) {
-    stream.Printf("nullptr");
+  if (!DumpCxxSmartPtrPointerSummary(stream, *ptr_sp, options))
     return true;
-  } else {
-    bool print_pointee = false;
-    Status error;
-    ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
-    if (pointee_sp && error.Success()) {
-      if (pointee_sp->DumpPrintableRepresentation(
-              stream, ValueObject::eValueObjectRepresentationStyleSummary,
-              lldb::eFormatInvalid,
-              ValueObject::PrintableRepresentationSpecialCases::eDisable,
-              false))
-        print_pointee = true;
-    }
-    if (!print_pointee)
-      stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
-  }
 
   if (count_sp)
     stream.Printf(" strong=%" PRIu64, 1 + count_sp->GetValueAsUnsigned(0));
@@ -210,24 +194,7 @@ bool lldb_private::formatters::LibcxxUniquePointerSummaryProvider(
   if (!ptr_sp)
     return false;
 
-  if (ptr_sp->GetValueAsUnsigned(0) == 0) {
-    stream.Printf("nullptr");
-    return true;
-  } else {
-    bool print_pointee = false;
-    Status error;
-    ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
-    if (pointee_sp && error.Success()) {
-      if (pointee_sp->DumpPrintableRepresentation(
-              stream, ValueObject::eValueObjectRepresentationStyleSummary,
-              lldb::eFormatInvalid,
-              ValueObject::PrintableRepresentationSpecialCases::eDisable,
-              false))
-        print_pointee = true;
-    }
-    if (!print_pointee)
-      stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
-  }
+  DumpCxxSmartPtrPointerSummary(stream, *ptr_sp, options);
 
   return true;
 }

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

@@ -156,14 +156,8 @@ bool LibStdcppUniquePtrSyntheticFrontEnd::GetSummary(
   if (!m_ptr_obj)
     return false;
 
-  bool success;
-  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);
+  DumpCxxSmartPtrPointerSummary(stream, *m_ptr_obj, options);
+
   return true;
 }
 

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py

@@ -31,15 +31,15 @@ def test_with_run_command(self):
         self.assertTrue(frame.IsValid())
 
         self.expect("frame variable nup", substrs=["nup = nullptr"])
-        self.expect("frame variable iup", substrs=["iup = 0x"])
-        self.expect("frame variable sup", substrs=["sup = 0x"])
+        self.expect("frame variable iup", substrs=["iup = 123"])
+        self.expect("frame variable sup", substrs=['sup = "foobar"'])
 
         self.expect("frame variable ndp", substrs=["ndp = nullptr"])
         self.expect(
-            "frame variable idp", substrs=["idp = 0x", "deleter = ", "a = 1", "b = 2"]
+            "frame variable idp", substrs=["idp = 456", "deleter = ", "a = 1", "b = 2"]
         )
         self.expect(
-            "frame variable sdp", substrs=["sdp = 0x", "deleter = ", "a = 3", "b = 4"]
+            "frame variable sdp", substrs=['sdp = "baz"', "deleter = ", "a = 3", "b = 4"]
         )
 
         self.assertEqual(
@@ -106,13 +106,13 @@ def test_recursive_unique_ptr(self):
             substrs=["stopped", "stop reason = breakpoint"],
         )
 
-        self.expect("frame variable f1->fp", substrs=["fp = 0x"])
+        self.expect("frame variable f1->fp", substrs=["fp = Foo @ 0x"])
         self.expect(
-            "frame variable --ptr-depth=1 f1->fp", substrs=["data = 2", "fp = 0x"]
+            "frame variable --ptr-depth=1 f1->fp", substrs=["data = 2", "fp = Foo @ 0x"]
         )
         self.expect(
             "frame variable --ptr-depth=2 f1->fp",
-            substrs=["data = 2", "fp = 0x", "data = 1"],
+            substrs=["data = 2", "fp = Foo @ 0x", "data = 1"],
         )
 
         frame = self.frame()