Conversion StreamerInfo not properly found if classes are unversioned.

[pcanal]

Check duplicate issues.

• Checked for duplicates

Description

When a class is schema evoled (see reproducer) using a renaming rules

At least on line 1258 of StreamerInfoReadBuffer.cxx:

                    subinfo = (TStreamerInfo*)newProxy->GetValueClass()->GetConversionStreamerInfo( oldProxy->GetValueClass(), vClVersion );

is not properly handling the case whether the classes are unversion and thus the search ought to be done using the checksum rather than the class version.

Reproducer

template <typename T>
struct Wrapper
{
   bool present = true;
   T obj;
};

struct MatchedCSCSegment
{
   float someValue = 0.0;

   MatchedCSCSegment(float in = 0.0) : someValue{in} {}

   // The simeple update fails if the class version is not set.
   ClassDef(MatchedCSCSegment, 5);
};

struct CSCSegment
{
   float someValue;

   operator MatchedCSCSegment()
   {
      return MatchedCSCSegment{someValue};
   }

#ifdef OLD_VERSION
   std::vector<CSCSegment> theDuplicateSegments;
   ClassDef(CSCSegment, 3);
#else
   std::vector<MatchedCSCSegment> theDuplicateSegments;

   ClassDef(CSCSegment, 4);
#endif
};

and rule:

#pragma read sourceClass="CSCSegment" targetClass="MatchedCSCSegment"

ROOT version

master

Installation method

any

Operating system

any

Additional context

No response

[pcanal]

conversionWithChecksum.tgz

contains the full example:

root.exe -b -l -q writedata.C+
root.exe -b -l -q simpleread.C+ 

***********************************
*    Row   * Instance * seg_split *
***********************************
Error in <TBufferFile::CheckByteCount>: object of class vector<CSCSegment> read too few bytes: 4 instead of 24
*        0 *        0 *         0 *
***********************************
Error in <TBufferFile::CheckByteCount>: object of class vector<MatchedCSCSegment> read too few bytes: 12 instead of 24
***********************************
*    Row   * Instance * seg_unspl *
***********************************
Error in <TBufferFile::CheckByteCount>: object of class vector<MatchedCSCSegment> read too few bytes: 12 instead of 24
Error in <TBufferFile::CheckByteCount>: object of class vector<MatchedCSCSegment> read too few bytes: 12 instead of 24
*        0 *        0 *         1 *
***********************************