Add mutual exclusion safety info on filter_fetch #9836
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In various WorldQuery implementations, we assume that `filter_fetch` and `fetch` are mutually exclusive, however nothing guarentees that. Documenting this assumption as a safety invariant is the least thing.
nicopap
added
A-ECS
alice-i-cecile
approved these changes
Sep 18, 2023
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Nevermind I'm silly. See updated description |
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do we need to update the safety comment on the call sites for filter_fetch too? |
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There is already a bunch of missing safety comments in the call sites (because it's inside |
james7132
approved these changes
Sep 19, 2023
rdrpenguin04
pushed a commit
to rdrpenguin04/bevy
that referenced
this pull request
Jan 9, 2024
# Objective Currently, in bevy, it's valid to do `Query<&mut Foo, Changed<Foo>>`. This assumes that `filter_fetch` and `fetch` are mutually exclusive, because of the mutable reference to the tick that `Mut<Foo>` implies and the reference that `Changed<Foo>` implies. However nothing guarantees that. ## Solution Documenting this assumption as a safety invariant is the least thing.
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Objective
Currently, in bevy, it's valid to do
Query<&mut Foo, Changed<Foo>>.This assumes that
filter_fetchandfetchare mutually exclusive, because of the mutable reference to the tick thatMut<Foo>implies and the reference thatChanged<Foo>implies. However nothing guarantees that.Solution
Documenting this assumption as a safety invariant is the least thing.