Fix SIGBUS crash in wechat_qrcode during process shutdown #4039
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Fixes opencv/opencv#27971 Problem: Double-free crash in std::vector<zxing::Ref<zxing::qrcode::Version>>::~vector() during process shutdown when using wechat_qrcode module. The crash occurred with error "free(): double free detected in tcache 2" and SIGBUS signal. Root Cause: Static member variable VERSIONS was destroyed during shutdown while Ref<Version> objects still held references, causing double-free due to static initialization order fiasco. Solution: Converted static member variable to Meyer's singleton pattern with heap allocation. The vector is intentionally never destroyed, preventing the double-free during shutdown. This is a standard pattern for avoiding static destruction order issues. Changes: - version.hpp: Changed VERSIONS declaration to getVersions() function - version.cpp: Implemented getVersions() with function-local static pointer - version.cpp: Updated all 15+ references to use getVersions() instead of VERSIONS Testing: - Existing tests pass without crashes - No SIGBUS crash on shutdown - Small intentional memory "leak" (singleton pattern) is acceptable
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Fixes opencv/opencv#27971
Problem:
Double-free crash in std::vector<zxing::Refzxing::qrcode::Version>::~vector()
during process shutdown when using wechat_qrcode module. The crash occurred with
error "free(): double free detected in tcache 2" and SIGBUS signal.
Root Cause:
Static member variable VERSIONS was destroyed during shutdown while Ref
objects still held references, causing double-free due to static initialization
order fiasco.
Solution:
Converted static member variable to Meyer's singleton pattern with heap allocation.
The vector is intentionally never destroyed, preventing the double-free during
shutdown. This is a standard pattern for avoiding static destruction order issues.
Changes:
Testing: