bevy/crates/bevy_ecs/macros
MiniaczQ e312da8c52
Reduce runtime panics through SystemParam validation (#15276)
# Objective

The goal of this PR is to introduce `SystemParam` validation in order to
reduce runtime panics.

Fixes #15265

## Solution

`SystemParam` now has a new method `validate_param(...) -> bool`, which
takes immutable variants of `get_param` arguments. The returned value
indicates whether the parameter can be acquired from the world. If
parameters cannot be acquired for a system, it won't be executed,
similarly to run conditions. This reduces panics when using params like
`Res`, `ResMut`, etc. as well as allows for new, ergonomic params like
#15264 or #15302.

Param validation happens at the level of executors. All validation
happens directly before executing a system, in case of normal systems
they are skipped, in case of conditions they return false.

Warning about system skipping is primitive and subject to change in
subsequent PRs.

## Testing

Two executor tests check that all executors:
- skip systems which have invalid parameters:
  - piped systems get skipped together,
  - dependent systems still run correctly,
- skip systems with invalid run conditions:
  - system conditions have invalid parameters,
  - system set conditions have invalid parameters.
2024-09-23 16:54:21 +00:00
..
src Reduce runtime panics through SystemParam validation (#15276) 2024-09-23 16:54:21 +00:00
Cargo.toml Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00