[io] Require manual rules for all leaf count arrays?

[hahnjo]

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Description

It appears that having a read rule for one leaf count array requires treatment of all arrays using the same leaf count branch.

Reproducer

A reproducer is SoAEvolv.multiple.tar.gz, which is writing

struct SoAEvolv {
   int fElements = 0;
   float *fA = nullptr; //[fElements]
   float *fB = nullptr; //[fElements]

   ClassDefNV(SoAEvolv, 2)
};

and then reading it back into

struct SoAEvolv {
   int fElements = 0;
   double *fA = nullptr; //[fElements]
   double *fB = nullptr; //[fElements]

   ClassDefNV(SoAEvolv, 3)
};

while trying to evolve it with

#pragma read sourceClass="SoAEvolv" source="int fElements; float *fA" version="[-2]" targetClass="SoAEvolv" target="fA" code="{printf(\"onfile.fA = %p\n\", onfile.fA); fA = new double[onfile.fElements]{onfile.fA[0]};}"

When running ./read_soaevolv the output is:

onfile.fA = 0x3236ef0
Error in <TBufferFile::CheckByteCount>: object of class SoAEvolv read too few bytes: 12 instead of 16
fA = 0x377f800, fB = 0

showing that the manual rule executed, but fB was not read and ROOT is reporting an error.

ROOT version

master

Installation method

from source

Operating system

Linux

Additional context

FYI @Electricks94