rustc_middle/hooks/
mod.rs

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1//! "Hooks" let you write `tcx` methods in downstream crates and call them in this crate, reducing
2//! the amount of code that needs to be in this crate (which is already very big). This is somewhat
3//! similar to queries, but queries come with a lot of machinery for caching and incremental
4//! compilation, whereas hooks are just plain function pointers without any of the query magic.
5
6use rustc_hir::def_id::{DefId, DefPathHash};
7use rustc_session::StableCrateId;
8use rustc_span::def_id::{CrateNum, LocalDefId};
9use rustc_span::{ExpnHash, ExpnId};
10
11use crate::mir;
12use crate::ty::{Ty, TyCtxt};
13
14macro_rules! declare_hooks {
15    ($($(#[$attr:meta])*hook $name:ident($($arg:ident: $K:ty),*) -> $V:ty;)*) => {
16
17        impl<'tcx> TyCtxt<'tcx> {
18            $(
19            $(#[$attr])*
20            #[inline(always)]
21            pub fn $name(self, $($arg: $K,)*) -> $V
22            {
23                (self.hooks.$name)(self, $($arg,)*)
24            }
25            )*
26        }
27
28        pub struct Providers {
29            $(pub $name: for<'tcx> fn(
30                TyCtxt<'tcx>,
31                $($arg: $K,)*
32            ) -> $V,)*
33        }
34
35        impl Default for Providers {
36            fn default() -> Self {
37                Providers {
38                    $($name: |_, $($arg,)*| default_hook(stringify!($name), &($($arg,)*))),*
39                }
40            }
41        }
42
43        impl Copy for Providers {}
44        impl Clone for Providers {
45            fn clone(&self) -> Self { *self }
46        }
47    };
48}
49
50declare_hooks! {
51    /// Tries to destructure an `mir::Const` ADT or array into its variant index
52    /// and its field values. This should only be used for pretty printing.
53    hook try_destructure_mir_constant_for_user_output(val: mir::ConstValue<'tcx>, ty: Ty<'tcx>) -> Option<mir::DestructuredConstant<'tcx>>;
54
55    /// Getting a &core::panic::Location referring to a span.
56    hook const_caller_location(file: rustc_span::Symbol, line: u32, col: u32) -> mir::ConstValue<'tcx>;
57
58    /// Returns `true` if this def is a function-like thing that is eligible for
59    /// coverage instrumentation under `-Cinstrument-coverage`.
60    ///
61    /// (Eligible functions might nevertheless be skipped for other reasons.)
62    hook is_eligible_for_coverage(key: LocalDefId) -> bool;
63
64    /// Imports all `SourceFile`s from the given crate into the current session.
65    /// This normally happens automatically when we decode a `Span` from
66    /// that crate's metadata - however, the incr comp cache needs
67    /// to trigger this manually when decoding a foreign `Span`
68    hook import_source_files(key: CrateNum) -> ();
69
70    hook expn_hash_to_expn_id(
71        cnum: CrateNum,
72        index_guess: u32,
73        hash: ExpnHash
74    ) -> ExpnId;
75
76    /// Converts a `DefPathHash` to its corresponding `DefId` in the current compilation
77    /// session, if it still exists. This is used during incremental compilation to
78    /// turn a deserialized `DefPathHash` into its current `DefId`.
79    /// Will fetch a DefId from a DefPathHash for a foreign crate.
80    hook def_path_hash_to_def_id_extern(hash: DefPathHash, stable_crate_id: StableCrateId) -> DefId;
81
82    /// Returns `true` if we should codegen an instance in the local crate, or returns `false` if we
83    /// can just link to the upstream crate and therefore don't need a mono item.
84    ///
85    /// Note: this hook isn't called within `rustc_middle` but #127779 suggests it's a hook instead
86    /// of a normal function because external tools might want to override it.
87    hook should_codegen_locally(instance: crate::ty::Instance<'tcx>) -> bool;
88
89    hook alloc_self_profile_query_strings() -> ();
90
91    /// Saves and writes the DepGraph to the file system.
92    ///
93    /// This function saves both the dep-graph and the query result cache,
94    /// and drops the result cache.
95    ///
96    /// This function should only run after all queries have completed.
97    /// Trying to execute a query afterwards would attempt to read the result cache we just dropped.
98    hook save_dep_graph() -> ();
99
100    hook query_key_hash_verify_all() -> ();
101
102    /// Ensure the given scalar is valid for the given type.
103    /// This checks non-recursive runtime validity.
104    hook validate_scalar_in_layout(scalar: crate::ty::ScalarInt, ty: Ty<'tcx>) -> bool;
105}
106
107#[cold]
108fn default_hook(name: &str, args: &dyn std::fmt::Debug) -> ! {
109    bug!(
110        "`tcx.{name}{args:?}` cannot be called as `{name}` was never assigned to a provider function"
111    )
112}
rustc_middle/hooks/mod.rs

rustc_middle/hooks/
mod.rs
