query.rs

#![allow(unused_parens)]

use crate::dep_graph;
use crate::infer::canonical::{self, Canonical};
use crate::lint::LintExpectation;
use crate::metadata::ModChild;
use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
use crate::middle::lib_features::LibFeatures;
use crate::middle::privacy::EffectiveVisibilities;
use crate::middle::resolve_bound_vars::{ObjectLifetimeDefault, ResolveBoundVars, ResolvedArg};
use crate::middle::stability::{self, DeprecationEntry};
use crate::mir;
use crate::mir::interpret::GlobalId;
use crate::mir::interpret::{
    ConstValue, EvalToAllocationRawResult, EvalToConstValueResult, EvalToValTreeResult,
};
use crate::mir::interpret::{LitToConstError, LitToConstInput};
use crate::mir::mono::CodegenUnit;
use crate::query::Key;
use crate::thir;
use crate::traits::query::{
    CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal,
    CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal,
    CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal, NoSolution,
};
use crate::traits::query::{
    DropckConstraint, DropckOutlivesResult, MethodAutoderefStepsResult, NormalizationResult,
    OutlivesBound,
};
use crate::traits::specialization_graph;
use crate::traits::{self, ImplSource};
use crate::ty::context::TyCtxtFeed;
use crate::ty::fast_reject::SimplifiedType;
use crate::ty::layout::InitKind;
use crate::ty::subst::{GenericArg, SubstsRef};
use crate::ty::util::AlwaysRequiresDrop;
use crate::ty::GeneratorDiagnosticData;
use crate::ty::{self, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt, UnusedGenericParams};
use rustc_arena::TypedArena;
use rustc_ast as ast;
use rustc_ast::expand::allocator::AllocatorKind;
use rustc_attr as attr;
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
use rustc_data_structures::steal::Steal;
use rustc_data_structures::svh::Svh;
use rustc_data_structures::sync::Lrc;
use rustc_data_structures::sync::WorkerLocal;
use rustc_data_structures::unord::UnordSet;
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_hir::def::{DefKind, DocLinkResMap};
use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, LocalDefId};
use rustc_hir::hir_id::OwnerId;
use rustc_hir::lang_items::{LangItem, LanguageItems};
use rustc_hir::{Crate, ItemLocalId, TraitCandidate};
use rustc_index::vec::IndexVec;
use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
use rustc_session::cstore::{CrateDepKind, CrateSource};
use rustc_session::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
use rustc_session::lint::LintExpectationId;
use rustc_session::Limits;
use rustc_span::symbol::Symbol;
use rustc_span::{Span, DUMMY_SP};
use rustc_target::abi;
use rustc_target::spec::PanicStrategy;
use std::mem;
use std::ops::Deref;
use std::path::PathBuf;
use std::sync::Arc;

pub(crate) use rustc_query_system::query::QueryJobId;
use rustc_query_system::query::*;

#[derive(Default)]
pub struct QuerySystem<'tcx> {
    pub arenas: QueryArenas<'tcx>,
    pub caches: QueryCaches<'tcx>,
}

#[derive(Copy, Clone)]
pub struct TyCtxtAt<'tcx> {
    pub tcx: TyCtxt<'tcx>,
    pub span: Span,
}

impl<'tcx> Deref for TyCtxtAt<'tcx> {
    type Target = TyCtxt<'tcx>;
    #[inline(always)]
    fn deref(&self) -> &Self::Target {
        &self.tcx
    }
}

#[derive(Copy, Clone)]
pub struct TyCtxtEnsure<'tcx> {
    pub tcx: TyCtxt<'tcx>,
}

impl<'tcx> TyCtxt<'tcx> {
    /// Returns a transparent wrapper for `TyCtxt`, which ensures queries
    /// are executed instead of just returning their results.
    #[inline(always)]
    pub fn ensure(self) -> TyCtxtEnsure<'tcx> {
        TyCtxtEnsure { tcx: self }
    }

    /// Returns a transparent wrapper for `TyCtxt` which uses
    /// `span` as the location of queries performed through it.
    #[inline(always)]
    pub fn at(self, span: Span) -> TyCtxtAt<'tcx> {
        TyCtxtAt { tcx: self, span }
    }

    pub fn try_mark_green(self, dep_node: &dep_graph::DepNode) -> bool {
        self.queries.try_mark_green(self, dep_node)
    }
}

macro_rules! query_helper_param_ty {
    (DefId) => { impl IntoQueryParam<DefId> };
    (LocalDefId) => { impl IntoQueryParam<LocalDefId> };
    ($K:ty) => { $K };
}

macro_rules! query_if_arena {
    ([] $arena:tt $no_arena:tt) => {
        $no_arena
    };
    ([(arena_cache) $($rest:tt)*] $arena:tt $no_arena:tt) => {
        $arena
    };
    ([$other:tt $($modifiers:tt)*]$($args:tt)*) => {
        query_if_arena!([$($modifiers)*]$($args)*)
    };
}

macro_rules! separate_provide_extern_decl {
    ([][$name:ident]) => {
        ()
    };
    ([(separate_provide_extern) $($rest:tt)*][$name:ident]) => {
        for<'tcx> fn(
            TyCtxt<'tcx>,
            query_keys::$name<'tcx>,
        ) -> query_provided::$name<'tcx>
    };
    ([$other:tt $($modifiers:tt)*][$($args:tt)*]) => {
        separate_provide_extern_decl!([$($modifiers)*][$($args)*])
    };
}

macro_rules! separate_provide_extern_default {
    ([][$name:ident]) => {
        ()
    };
    ([(separate_provide_extern) $($rest:tt)*][$name:ident]) => {
        |_, key| bug!(
            "`tcx.{}({:?})` unsupported by its crate; \
             perhaps the `{}` query was never assigned a provider function",
            stringify!($name),
            key,
            stringify!($name),
        )
    };
    ([$other:tt $($modifiers:tt)*][$($args:tt)*]) => {
        separate_provide_extern_default!([$($modifiers)*][$($args)*])
    };
}

macro_rules! opt_remap_env_constness {
    ([][$name:ident]) => {};
    ([(remap_env_constness) $($rest:tt)*][$name:ident]) => {
        let $name = $name.without_const();
    };
    ([$other:tt $($modifiers:tt)*][$name:ident]) => {
        opt_remap_env_constness!([$($modifiers)*][$name])
    };
}

macro_rules! define_callbacks {
    (
     $($(#[$attr:meta])*
        [$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => {

        // HACK(eddyb) this is like the `impl QueryConfig for queries::$name`
        // below, but using type aliases instead of associated types, to bypass
        // the limitations around normalizing under HRTB - for example, this:
        // `for<'tcx> fn(...) -> <queries::$name<'tcx> as QueryConfig<TyCtxt<'tcx>>>::Value`
        // doesn't currently normalize to `for<'tcx> fn(...) -> query_values::$name<'tcx>`.
        // This is primarily used by the `provide!` macro in `rustc_metadata`.
        #[allow(nonstandard_style, unused_lifetimes)]
        pub mod query_keys {
            use super::*;

            $(pub type $name<'tcx> = $($K)*;)*
        }
        #[allow(nonstandard_style, unused_lifetimes)]
        pub mod query_values {
            use super::*;

            $(pub type $name<'tcx> = $V;)*
        }

        /// This module specifies the type returned from query providers and the type used for
        /// decoding. For regular queries this is the declared returned type `V`, but
        /// `arena_cache` will use `<V as Deref>::Target` instead.
        #[allow(nonstandard_style, unused_lifetimes)]
        pub mod query_provided {
            use super::*;

            $(
                pub type $name<'tcx> = query_if_arena!([$($modifiers)*] (<$V as Deref>::Target) ($V));
            )*
        }

        /// This module has a function per query which takes a `query_provided` value and coverts
        /// it to a regular `V` value by allocating it on an arena if the query has the
        /// `arena_cache` modifier. This will happen when computing the query using a provider or
        /// decoding a stored result.
        #[allow(nonstandard_style, unused_lifetimes)]
        pub mod query_provided_to_value {
            use super::*;

            $(
                #[inline(always)]
                pub fn $name<'tcx>(
                    _tcx: TyCtxt<'tcx>,
                    value: query_provided::$name<'tcx>,
                ) -> query_values::$name<'tcx> {
                    query_if_arena!([$($modifiers)*]
                        {
                            if mem::needs_drop::<query_provided::$name<'tcx>>() {
                                &*_tcx.query_system.arenas.$name.alloc(value)
                            } else {
                                &*_tcx.arena.dropless.alloc(value)
                            }
                        }
                        (value)
                    )
                }
            )*
        }
        #[allow(nonstandard_style, unused_lifetimes)]
        pub mod query_storage {
            use super::*;

            $(
                pub type $name<'tcx> = <<$($K)* as Key>::CacheSelector as CacheSelector<'tcx, $V>>::Cache;
            )*
        }

        pub struct QueryArenas<'tcx> {
            $($(#[$attr])* pub $name: query_if_arena!([$($modifiers)*]
                (WorkerLocal<TypedArena<<$V as Deref>::Target>>)
                ()
            ),)*
        }

        impl Default for QueryArenas<'_> {
            fn default() -> Self {
                Self {
                    $($name: query_if_arena!([$($modifiers)*]
                        (WorkerLocal::new(|_| Default::default()))
                        ()
                    ),)*
                }
            }
        }

        #[derive(Default)]
        pub struct QueryCaches<'tcx> {
            $($(#[$attr])* pub $name: query_storage::$name<'tcx>,)*
        }

        impl<'tcx> TyCtxtEnsure<'tcx> {
            $($(#[$attr])*
            #[inline(always)]
            pub fn $name(self, key: query_helper_param_ty!($($K)*)) {
                let key = key.into_query_param();
                opt_remap_env_constness!([$($modifiers)*][key]);

                match try_get_cached(self.tcx, &self.tcx.query_system.caches.$name, &key) {
                    Some(_) => return,
                    None => self.tcx.queries.$name(self.tcx, DUMMY_SP, key, QueryMode::Ensure),
                };
            })*
        }

        impl<'tcx> TyCtxt<'tcx> {
            $($(#[$attr])*
            #[inline(always)]
            #[must_use]
            pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V
            {
                self.at(DUMMY_SP).$name(key)
            })*
        }

        impl<'tcx> TyCtxtAt<'tcx> {
            $($(#[$attr])*
            #[inline(always)]
            pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V
            {
                let key = key.into_query_param();
                opt_remap_env_constness!([$($modifiers)*][key]);

                match try_get_cached(self.tcx, &self.tcx.query_system.caches.$name, &key) {
                    Some(value) => value,
                    None => self.tcx.queries.$name(self.tcx, self.span, key, QueryMode::Get).unwrap(),
                }
            })*
        }

        pub struct Providers {
            $(pub $name: for<'tcx> fn(
                TyCtxt<'tcx>,
                query_keys::$name<'tcx>,
            ) -> query_provided::$name<'tcx>,)*
        }

        pub struct ExternProviders {
            $(pub $name: separate_provide_extern_decl!([$($modifiers)*][$name]),)*
        }

        impl Default for Providers {
            fn default() -> Self {
                use crate::query::Key;

                Providers {
                    $($name: |_, key| bug!(
                        "`tcx.{}({:?})` is not supported for {} crate;\n
                        hint: Queries can be either made to the local crate, or the external crate. This error means you tried to use it for one that's not supported.\n
                        If that's not the case, {} was likely never assigned to a provider function.\n",
                        stringify!($name),
                        key,
                        if key.query_crate_is_local() { "local" } else { "external" },
                        stringify!($name),
                    ),)*
                }
            }
        }

        impl Default for ExternProviders {
            fn default() -> Self {
                ExternProviders {
                    $($name: separate_provide_extern_default!([$($modifiers)*][$name]),)*
                }
            }
        }

        impl Copy for Providers {}
        impl Clone for Providers {
            fn clone(&self) -> Self { *self }
        }

        impl Copy for ExternProviders {}
        impl Clone for ExternProviders {
            fn clone(&self) -> Self { *self }
        }

        pub trait QueryEngine<'tcx>: rustc_data_structures::sync::Sync {
            fn as_any(&'tcx self) -> &'tcx dyn std::any::Any;

            fn try_mark_green(&'tcx self, tcx: TyCtxt<'tcx>, dep_node: &dep_graph::DepNode) -> bool;

            $($(#[$attr])*
            fn $name(
                &'tcx self,
                tcx: TyCtxt<'tcx>,
                span: Span,
                key: query_keys::$name<'tcx>,
                mode: QueryMode,
            ) -> Option<$V>;)*
        }
    };
}

macro_rules! hash_result {
    ([]) => {{
        Some(dep_graph::hash_result)
    }};
    ([(no_hash) $($rest:tt)*]) => {{
        None
    }};
    ([$other:tt $($modifiers:tt)*]) => {
        hash_result!([$($modifiers)*])
    };
}

macro_rules! define_feedable {
    ($($(#[$attr:meta])* [$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => {
        $(impl<'tcx, K: IntoQueryParam<$($K)*> + Copy> TyCtxtFeed<'tcx, K> {
            $(#[$attr])*
            #[inline(always)]
            pub fn $name(self, value: query_provided::$name<'tcx>) -> $V {
                let key = self.key().into_query_param();
                opt_remap_env_constness!([$($modifiers)*][key]);

                let tcx = self.tcx;
                let value = query_provided_to_value::$name(tcx, value);
                let cache = &tcx.query_system.caches.$name;

                match try_get_cached(tcx, cache, &key) {
                    Some(old) => {
                        bug!(
                            "Trying to feed an already recorded value for query {} key={key:?}:\nold value: {old:?}\nnew value: {value:?}",
                            stringify!($name),
                        )
                    }
                    None => {
                        let dep_node = dep_graph::DepNode::construct(tcx, dep_graph::DepKind::$name, &key);
                        let dep_node_index = tcx.dep_graph.with_feed_task(
                            dep_node,
                            tcx,
                            key,
                            &value,
                            hash_result!([$($modifiers)*]),
                        );
                        cache.complete(key, value, dep_node_index);
                        value
                    }
                }
            }
        })*
    }
}

// Each of these queries corresponds to a function pointer field in the
// `Providers` struct for requesting a value of that type, and a method
// on `tcx: TyCtxt` (and `tcx.at(span)`) for doing that request in a way
// which memoizes and does dep-graph tracking, wrapping around the actual
// `Providers` that the driver creates (using several `rustc_*` crates).
//
// The result type of each query must implement `Clone`, and additionally
// `ty::query::values::Value`, which produces an appropriate placeholder
// (error) value if the query resulted in a query cycle.
// Queries marked with `fatal_cycle` do not need the latter implementation,
// as they will raise an fatal error on query cycles instead.

rustc_query_append! { define_callbacks! }
rustc_feedable_queries! { define_feedable! }

mod sealed {
    use super::{DefId, LocalDefId, OwnerId};

    /// An analogue of the `Into` trait that's intended only for query parameters.
    ///
    /// This exists to allow queries to accept either `DefId` or `LocalDefId` while requiring that the
    /// user call `to_def_id` to convert between them everywhere else.
    pub trait IntoQueryParam<P> {
        fn into_query_param(self) -> P;
    }

    impl<P> IntoQueryParam<P> for P {
        #[inline(always)]
        fn into_query_param(self) -> P {
            self
        }
    }

    impl<'a, P: Copy> IntoQueryParam<P> for &'a P {
        #[inline(always)]
        fn into_query_param(self) -> P {
            *self
        }
    }

    impl IntoQueryParam<LocalDefId> for OwnerId {
        #[inline(always)]
        fn into_query_param(self) -> LocalDefId {
            self.def_id
        }
    }

    impl IntoQueryParam<DefId> for LocalDefId {
        #[inline(always)]
        fn into_query_param(self) -> DefId {
            self.to_def_id()
        }
    }

    impl IntoQueryParam<DefId> for OwnerId {
        #[inline(always)]
        fn into_query_param(self) -> DefId {
            self.to_def_id()
        }
    }
}

use sealed::IntoQueryParam;

impl<'tcx> TyCtxt<'tcx> {
    pub fn def_kind(self, def_id: impl IntoQueryParam<DefId>) -> DefKind {
        let def_id = def_id.into_query_param();
        self.opt_def_kind(def_id)
            .unwrap_or_else(|| bug!("def_kind: unsupported node: {:?}", def_id))
    }
}

impl<'tcx> TyCtxtAt<'tcx> {
    pub fn def_kind(self, def_id: impl IntoQueryParam<DefId>) -> DefKind {
        let def_id = def_id.into_query_param();
        self.opt_def_kind(def_id)
            .unwrap_or_else(|| bug!("def_kind: unsupported node: {:?}", def_id))
    }
}