Struct LocalLevelCell 

pub struct LocalLevelCell { /* private fields */ }

locallevel storage: shared for parameter scoping, per-thread for diagnostics.

!!! WARNING: RUST-ONLY !!! C has one int locallevel (Src/params.c:54) serving both jobs, because with one thread they are the same number.

zshrs cannot simply make it per-thread. locallevel is the level a parameter is STAMPED with (Src/params.c:5837 locallevel++ in startparamscope) and the level scanendscope compares every entry against on scope exit (Src/params.c:5904-5907, if (pm->level > locallevel)) — and the param table those stamps live in is one shared table that async_precmd hooks deliberately write into. Give each thread its own counter and two threads both stamp level 1 in the same table, so one thread’s endparamscope deletes the other’s locals: a strictly worse version of the $BUFFER loss quiesce was added for. So load — every parameter-scoping reader — keeps returning the shared value, unchanged.

What a worker must NOT contaminate is the other job: the “am I inside a function” test the error formatters make (Src/utils.c:150 if (unset(SHINSTDIN) || locallevel), :301 in zerrmsg). A hook running on a worker raised the shared counter, and an error the user caused at top level came out formatted as if it had happened inside a function — with a line number and a function-name prefix zsh does not print. here answers that question for the CALLING thread, and the formatters read it.

Every mutation goes through this type, so the per-thread depth cannot drift away from the sites that move the shared counter: the four methods below are the entire mutation surface of params::locallevel.

Implementations

impl LocalLevelCell

pub const fn new() -> Self

A top-level counter. const so locallevel stays a plain static.

pub fn load(&self, order: Ordering) -> i32

Mirrors AtomicI32::load — the SHARED counter, for param scoping.

pub fn store(&self, val: i32, order: Ordering)

Mirrors AtomicI32::store. Sites that save and restore the whole counter (computil’s comparguments bracket, param_private’s hoist) mean “this thread is now at level v”, so the thread’s own depth follows.

pub fn fetch_add(&self, val: i32, order: Ordering) -> i32

Mirrors AtomicI32::fetch_add, returning the previous SHARED value.

pub fn fetch_sub(&self, val: i32, order: Ordering) -> i32

Mirrors AtomicI32::fetch_sub, returning the previous SHARED value.

pub fn here(&self) -> i32

The calling thread’s OWN function-scope depth — what C’s locallevel would read if this thread were the only one, which is what the error formatters need. Clamped at zero: a thread whose first act is endparamscope (a scope opened before it existed) would otherwise report a negative depth.

Trait Implementations

impl Default for LocalLevelCell

fn default() -> Self

Returns the “default value” for a type.