TTree: Prevent access to already deleted scratch area #19938
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Pull Request Overview
This PR addresses a bug in TTree where previously read data from a deleted scratch area could be accessed incorrectly for associative containers. The fix involves preventing duplicate reads on associative containers when the same entry is accessed multiple times, and ensures proper reset of read entry cursors for sub-branches.
Key changes:
- Added helper function to identify associative containers and prevent duplicate reads
- Modified entry reading logic to handle associative containers specially
- Added recursive reset functionality for sub-branch read cursors
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Test Results 21 files 21 suites 3d 13h 46m 11s ⏱️ Results for commit b1d4ac1. ♻️ This comment has been updated with latest results. |
Fix one case that had not been updated to support multimap/multiset.
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The flow for reading an STL associative container is:
(a) Read branch count
(b) load sub-branch data into a staging/temporary area
(c) copy/insert that data into the associative container
Previously doing a direct read like:
tree->GetBranch("map.second")->GetEntry(e);
was leading to 'write' into deleted memory.
This directly test the use pattern applied by TTree::Scan/Draw
This allow to document the 2 sets of similar test at the same place to contrast them
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Fixes #19963