Fix ASAN thread race with TLS dynamic initialization of variable_registry

[saxena-anurag]

Problem

When running under AddressSanitizer (ASan), extra threads are spawned before the CRT debug locks are fully initialized. The thread_local VariableRegistry variable_registry global variable triggered TLS dynamic-init callbacks that could race with CRT startup on these early threads, leading to heap-buffer-overflow or other undefined behavior.

Solution

Replace the file-scope thread_local variable with a function-local thread_local inside a getter function (get_variable_registry()). This defers construction until the first actual use rather than running during TLS dynamic initialization, avoiding the race condition with early-spawned threads.

A backward-compatible #define variable_registry macro alias is provided so all existing call sites continue to work without modification.

Changes

• src/crab/var_registry.hpp: Replace extern thread_local VariableRegistry variable_registry with VariableRegistry& get_variable_registry() declaration and a backward-compatible macro alias.
• src/crab/var_registry.cpp: Move the thread_local instance inside a function-local scope in get_variable_registry().

Testing

All 1533 tests pass (1295 passed, 1 skipped, 237 failed as expected — no change from baseline).

[coderabbitai]

📝 Walkthrough

Walkthrough

Refactors the global thread-local VariableRegistry from a translation-unit scoped variable to a function-local accessor pattern. Introduces get_variable_registry() function for deferred initialization, with a macro alias for backward compatibility.

Changes

Cohort / File(s)	Summary
Variable Registry Thread-Local Refactoring src/crab/var_registry.hpp, src/crab/var_registry.cpp	Replaces extern thread_local VariableRegistry variable_registry with get_variable_registry() function returning deferred-initialized thread-local instance. Adds macro alias variable_registry mapping to get_variable_registry() for backward compatibility. Updates operator<< to use the new accessor.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the problem, solution, code changes, and test results, all directly related to the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title accurately summarizes the main change: replacing a file-scoped thread_local variable with a function-local getter to resolve an ASAN thread race condition during TLS dynamic initialization.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[saxena-anurag]

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