Module sizes 

Compile-time opaque storage sizes for FFI consumers.

See sizes for the export_size! pattern used to expose these values to nros-c / nros-cpp at build time. Single source of truth for FFI opaque-storage sizes.

Each export_size! invocation produces two artefacts:

• pub const FOO_SIZE: usize = core::mem::size_of::<T>(); — a normal Rust const suitable for in-crate const _: () = assert!(...) checks and direct use by no_std consumers.
• pub static __NROS_SIZE_FOO: [u8; FOO_SIZE] = [0; FOO_SIZE]; — an array-sized static whose symbol storage size in the compiled rlib equals FOO_SIZE. nros-c/nros-cpp build scripts read the sizes out via nros_sizes_build::extract_sizes to derive opaque-storage macros for the generated C/C++ headers.

The markers exist ONLY in the size probe’s own build (issue 1765)

The statics, and the __NROS_SIZE_FN_* fn-pointer markers beside them, are compiled only under feature = "ffi-size-markers". Exactly one party requests that feature: the nested probe cargo behind nros-build-helpers::shared::probe_nros_sizes, which builds nros in its OWN target directory. No shipped dep-site enables it, and build.rs makes enabling it outside the probe a compile error.

It used to be requested on nros-c’s and nros-cpp‘s nros dependency, so the markers were part of the linked staticlib: #[no_mangle] immutable statics, which a staticlib exports and the board linker scripts place in .text. Every C/C++ image paid the SUM of the probed sizes in flash, as zero bytes (111,252 B of a 587,256 B FreeRTOS C zenoh talker), and once phase-382 W3’ carved the parameter store into EXECUTOR_SIZE, a second 280 KB copy of the store. The pub consts are unaffected: they are what in-crate asserts and no_std consumers read, and a const occupies nothing.

Feature gating follows the rest of the crate: the statics only exist when an RMW backend (rmw-zenoh / rmw-xrce / rmw-cyclonedds / rmw-cffi) is active, which is exactly the condition under which the Rmw* type aliases resolve. Workspace-level cargo check without any RMW feature sees this module as empty.

Constants

ACTION_SERVER_INTERNAL_SIZE

ACTION_SERVER_RAW_HANDLE_SIZE

CPP_ACTION_CLIENT_SIZE

CPP_ACTION_SERVER_SIZE

EXECUTOR_SIZE

EXECUTOR_VALUE_SIZE

GUARD_CONDITION_SIZE

LIFECYCLE_CTX_SIZE

PUBLISHER_SIZE

RAW_ACTION_CLIENT_SIZE

RAW_ACTION_SERVER_SIZE

RAW_SERVICE_CLIENT_SIZE

RAW_SERVICE_SERVER_SIZE

RAW_SUBSCRIPTION_SIZE

SERVICE_CLIENT_SIZE

SERVICE_SERVER_SIZE

SESSION_SIZE

SUBSCRIBER_SIZE