bjoernager/rust
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Add/clarify comments about hooks.

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Explaining things that weren't clear to me at first.
This commit is contained in:
Nicholas Nethercote 2025-01-31 15:03:50 +11:00
parent 6ac8878615
commit be1aa7bb2a
1 changed files with 7 additions and 4 deletions
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11
compiler/rustc_middle/src/hooks/mod.rs
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@ -1,7 +1,7 @@
//! "Hooks" provide a way for `tcx` functionality to be provided by some downstream crate without
//! everything in rustc having to depend on that crate. This is somewhat similar to queries, but
//! queries come with a lot of machinery for caching and incremental compilation, whereas hooks are
//! just plain function pointers without any of the query magic.
//! "Hooks" let you write `tcx` methods in downstream crates and call them in this crate, reducing
//! the amount of code that needs to be in this crate (which is already very big). This is somewhat
//! similar to queries, but queries come with a lot of machinery for caching and incremental
//! compilation, whereas hooks are just plain function pointers without any of the query magic.
use rustc_hir::def_id::{DefId, DefPathHash};
use rustc_session::StableCrateId;
@ -107,6 +107,9 @@ declare_hooks! {
/// Returns `true` if we should codegen an instance in the local crate, or returns `false` if we
/// can just link to the upstream crate and therefore don't need a mono item.
///
/// Note: this hook isn't called within `rustc_middle` but #127779 suggests it's a hook instead
/// of a normal function because external tools might want to override it.
hook should_codegen_locally(instance: crate::ty::Instance<'tcx>) -> bool;
hook alloc_self_profile_query_strings() -> ();