FixedBufferAllocator: Does free() reclaim memory for subsequent allocations?

When using std.heap.FixedBufferAllocator, the allocator is limited to a caller‑supplied byte slice. The documentation states that the allocator never falls back to the system allocator and that allocation is bump‑pointer style. However, it is unclear whether calling free() on a non‑most‑recent allocation releases that region for future allocations, or whether the memory remains permanently consumed until the allocator is reset.

Because the standard library’s allocator interface has evolved across Zig releases, the current behavior might differ from earlier versions. Understanding this is critical for data structures that frequently free and reallocate out of order, such as ArrayList or custom hash maps built atop the allocator.

What is the exact semantics of free() in the current Zig standard library for FixedBufferAllocator? Does it reclaim the freed block for later allocations, or is the memory only recoverable by resetting the allocator? If it does not reclaim memory, is there a documented pattern (e.g., resize or resetting the allocator) that allows reuse of freed space? How do Zig std components that rely on this allocator handle the potential lack of memory reclamation?