pub fn value_semantics_enabled() -> boolExpand description
Whether Mutable Value Semantics (copy-on-write for collections) is enabled.
Value semantics is the DEFAULT (all four tiers — tree-walker, VM, AOT, JIT —
implement it). LOGOS_VALUE_SEMANTICS=0 restores the historical reference
semantics (escape hatch). A thread-local ReferenceScope also forces
reference semantics for the duration of compile-time PE / self-interpreter
execution (bootstrap-scope). The env var is read once and cached; the
thread-local check is a single Cell read, so the hot path stays cheap.