Add a way to decouple the implementation and the declaration of a TyCtxt method.

compiler/rustc_codegen_gcc/src/lib.rs

@@ -80,7 +80,7 @@ use rustc_errors::{DiagnosticMessage, ErrorGuaranteed, Handler, SubdiagnosticMes
 use rustc_fluent_macro::fluent_messages;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::query::Providers;
+use rustc_middle::util::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{Lto, OptLevel, OutputFilenames};
 use rustc_session::Session;

compiler/rustc_codegen_llvm/src/lib.rs

@@ -39,8 +39,8 @@ use rustc_errors::{DiagnosticMessage, ErrorGuaranteed, FatalError, Handler, Subd
 use rustc_fluent_macro::fluent_messages;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
+use rustc_middle::util::Providers;
 use rustc_session::config::{OptLevel, OutputFilenames, PrintKind, PrintRequest};
 use rustc_session::Session;
 use rustc_span::symbol::Symbol;

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -11,10 +11,10 @@ use rustc_middle::middle::exported_symbols::{
     metadata_symbol_name, ExportedSymbol, SymbolExportInfo, SymbolExportKind, SymbolExportLevel,
 };
 use rustc_middle::query::LocalCrate;
-use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::{self, SymbolName, TyCtxt};
 use rustc_middle::ty::{GenericArgKind, GenericArgsRef};
+use rustc_middle::util::Providers;
 use rustc_session::config::{CrateType, OomStrategy};
 use rustc_target::spec::SanitizerSet;
 
@@ -457,11 +457,9 @@ pub fn provide(providers: &mut Providers) {
     providers.is_unreachable_local_definition = is_unreachable_local_definition_provider;
     providers.upstream_drop_glue_for = upstream_drop_glue_for_provider;
     providers.wasm_import_module_map = wasm_import_module_map;
-}
-
-pub fn provide_extern(providers: &mut ExternProviders) {
-    providers.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
-    providers.upstream_monomorphizations_for = upstream_monomorphizations_for_provider;
+    providers.extern_queries.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
+    providers.extern_queries.upstream_monomorphizations_for =
+        upstream_monomorphizations_for_provider;
 }
 
 fn symbol_export_level(tcx: TyCtxt<'_>, sym_def_id: DefId) -> SymbolExportLevel {

compiler/rustc_codegen_ssa/src/lib.rs

@@ -31,7 +31,7 @@ use rustc_middle::dep_graph::WorkProduct;
 use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Dependencies;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
-use rustc_middle::query::{ExternProviders, Providers};
+use rustc_middle::util::Providers;
 use rustc_serialize::opaque::{FileEncoder, MemDecoder};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use rustc_session::config::{CrateType, OutputFilenames, OutputType, RUST_CGU_EXT};
@@ -190,10 +190,6 @@ pub fn provide(providers: &mut Providers) {
     crate::codegen_attrs::provide(providers);
 }
 
-pub fn provide_extern(providers: &mut ExternProviders) {
-    crate::back::symbol_export::provide_extern(providers);
-}
-
 /// Checks if the given filename ends with the `.rcgu.o` extension that `rustc`
 /// uses for the object files it generates.
 pub fn looks_like_rust_object_file(filename: &str) -> bool {

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -11,9 +11,9 @@ use rustc_data_structures::sync::{DynSend, DynSync};
 use rustc_errors::ErrorGuaranteed;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
 use rustc_middle::ty::{Ty, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_session::{
     config::{self, OutputFilenames, PrintRequest},
     cstore::MetadataLoaderDyn,
@@ -85,7 +85,6 @@ pub trait CodegenBackend {
     }
 
     fn provide(&self, _providers: &mut Providers) {}
-    fn provide_extern(&self, _providers: &mut ExternProviders) {}
     fn codegen_crate<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -4,6 +4,7 @@ use crate::errors::MaxNumNodesInConstErr;
 use crate::interpret::{intern_const_alloc_recursive, InternKind, InterpCx, Scalar};
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId};
+use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
 
@@ -86,17 +87,17 @@ pub(crate) fn eval_to_valtree<'tcx>(
 
 #[instrument(skip(tcx), level = "debug")]
 pub(crate) fn try_destructure_mir_constant_for_diagnostics<'tcx>(
-    tcx: TyCtxt<'tcx>,
+    tcx: TyCtxtAt<'tcx>,
     val: mir::ConstValue<'tcx>,
     ty: Ty<'tcx>,
 ) -> Option<mir::DestructuredConstant<'tcx>> {
     let param_env = ty::ParamEnv::reveal_all();
-    let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
+    let ecx = mk_eval_cx(tcx.tcx, tcx.span, param_env, CanAccessStatics::No);
     let op = ecx.const_val_to_op(val, ty, None).ok()?;
 
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match ty.kind() {
-        ty::Array(_, len) => (len.eval_target_usize(tcx, param_env) as usize, None, op),
+        ty::Array(_, len) => (len.eval_target_usize(tcx.tcx, param_env) as usize, None, op),
         ty::Adt(def, _) if def.variants().is_empty() => {
             return None;
         }

compiler/rustc_const_eval/src/lib.rs

@@ -38,8 +38,7 @@ pub use errors::ReportErrorExt;
 
 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
 use rustc_fluent_macro::fluent_messages;
-use rustc_middle::query::Providers;
-use rustc_middle::ty;
+use rustc_middle::{ty, util::Providers};
 
 fluent_messages! { "../messages.ftl" }
 
@@ -52,8 +51,8 @@ pub fn provide(providers: &mut Providers) {
         let (param_env, raw) = param_env_and_value.into_parts();
         const_eval::eval_to_valtree(tcx, param_env, raw)
     };
-    providers.try_destructure_mir_constant_for_diagnostics =
-        |tcx, (cv, ty)| const_eval::try_destructure_mir_constant_for_diagnostics(tcx, cv, ty);
+    providers.hooks.try_destructure_mir_constant_for_diagnostics =
+        const_eval::try_destructure_mir_constant_for_diagnostics;
     providers.valtree_to_const_val = |tcx, (ty, valtree)| {
         const_eval::valtree_to_const_value(tcx, ty::ParamEnv::empty().and(ty), valtree)
     };

compiler/rustc_interface/src/interface.rs

@@ -9,7 +9,7 @@ use rustc_data_structures::sync::Lrc;
 use rustc_errors::registry::Registry;
 use rustc_errors::{ErrorGuaranteed, Handler};
 use rustc_lint::LintStore;
-use rustc_middle::query::{ExternProviders, Providers};
+use rustc_middle::util::Providers;
 use rustc_middle::{bug, ty};
 use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_query_impl::QueryCtxt;
@@ -37,7 +37,7 @@ pub struct Compiler {
     pub(crate) sess: Lrc<Session>,
     codegen_backend: Lrc<dyn CodegenBackend>,
     pub(crate) register_lints: Option<Box<dyn Fn(&Session, &mut LintStore) + Send + Sync>>,
-    pub(crate) override_queries: Option<fn(&Session, &mut Providers, &mut ExternProviders)>,
+    pub(crate) override_queries: Option<fn(&Session, &mut Providers)>,
 }
 
 impl Compiler {
@@ -271,7 +271,7 @@ pub struct Config {
     /// the list of queries.
     ///
     /// The second parameter is local providers and the third parameter is external providers.
-    pub override_queries: Option<fn(&Session, &mut Providers, &mut ExternProviders)>,
+    pub override_queries: Option<fn(&Session, &mut Providers)>,
 
     /// This is a callback from the driver that is called to create a codegen backend.
     pub make_codegen_backend:

compiler/rustc_interface/src/lib.rs

@@ -25,7 +25,7 @@ pub mod util;
 
 pub use callbacks::setup_callbacks;
 pub use interface::{run_compiler, Config};
-pub use passes::{DEFAULT_EXTERN_QUERY_PROVIDERS, DEFAULT_QUERY_PROVIDERS};
+pub use passes::DEFAULT_QUERY_PROVIDERS;
 pub use queries::Queries;
 
 #[cfg(test)]

compiler/rustc_interface/src/passes.rs

@@ -18,8 +18,8 @@ use rustc_lint::{unerased_lint_store, BufferedEarlyLint, EarlyCheckNode, LintSto
 use rustc_metadata::creader::CStore;
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
-use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::{self, GlobalCtxt, RegisteredTools, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_mir_build as mir_build;
 use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str, validate_attr};
 use rustc_passes::{self, abi_test, hir_stats, layout_test};
@@ -675,13 +675,6 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     *providers
 });
 
-pub static DEFAULT_EXTERN_QUERY_PROVIDERS: LazyLock<ExternProviders> = LazyLock::new(|| {
-    let mut extern_providers = ExternProviders::default();
-    rustc_metadata::provide_extern(&mut extern_providers);
-    rustc_codegen_ssa::provide_extern(&mut extern_providers);
-    extern_providers
-});
-
 pub fn create_global_ctxt<'tcx>(
     compiler: &'tcx Compiler,
     crate_types: Vec<CrateType>,
@@ -702,14 +695,11 @@ pub fn create_global_ctxt<'tcx>(
     let query_result_on_disk_cache = rustc_incremental::load_query_result_cache(sess);
 
     let codegen_backend = compiler.codegen_backend();
-    let mut local_providers = *DEFAULT_QUERY_PROVIDERS;
-    codegen_backend.provide(&mut local_providers);
-
-    let mut extern_providers = *DEFAULT_EXTERN_QUERY_PROVIDERS;
-    codegen_backend.provide_extern(&mut extern_providers);
+    let mut providers = *DEFAULT_QUERY_PROVIDERS;
+    codegen_backend.provide(&mut providers);
 
     if let Some(callback) = compiler.override_queries {
-        callback(sess, &mut local_providers, &mut extern_providers);
+        callback(sess, &mut providers);
     }
 
     let incremental = dep_graph.is_fully_enabled();
@@ -727,11 +717,12 @@ pub fn create_global_ctxt<'tcx>(
                 dep_graph,
                 rustc_query_impl::query_callbacks(arena),
                 rustc_query_impl::query_system(
-                    local_providers,
-                    extern_providers,
+                    providers.queries,
+                    providers.extern_queries,
                     query_result_on_disk_cache,
                     incremental,
                 ),
+                providers.hooks,
             )
         })
     })

compiler/rustc_metadata/src/lib.rs

@@ -26,7 +26,7 @@ extern crate rustc_middle;
 #[macro_use]
 extern crate tracing;
 
-pub use rmeta::{provide, provide_extern};
+pub use rmeta::provide;
 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
 use rustc_fluent_macro::fluent_messages;
 

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -44,7 +44,6 @@ use std::sync::atomic::Ordering;
 use std::{io, iter, mem};
 
 pub(super) use cstore_impl::provide;
-pub use cstore_impl::provide_extern;
 use rustc_span::hygiene::HygieneDecodeContext;
 
 mod cstore_impl;

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -14,10 +14,11 @@ use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
+use rustc_middle::query::ExternProviders;
 use rustc_middle::query::LocalCrate;
-use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_session::cstore::CrateStore;
 use rustc_session::{Session, StableCrateId};
 use rustc_span::hygiene::{ExpnHash, ExpnId};
@@ -147,7 +148,7 @@ macro_rules! provide_one {
 macro_rules! provide {
     ($tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
       $($name:ident => { $($compute:tt)* })*) => {
-        pub fn provide_extern(providers: &mut ExternProviders) {
+        fn provide_extern(providers: &mut ExternProviders) {
             $(provide_one! {
                 $tcx, $def_id, $other, $cdata, $name => { $($compute)* }
             })*
@@ -385,7 +386,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
     // FIXME(#44234) - almost all of these queries have no sub-queries and
     // therefore no actual inputs, they're just reading tables calculated in
     // resolve! Does this work? Unsure! That's what the issue is about
-    *providers = Providers {
+    providers.queries = rustc_middle::query::Providers {
         allocator_kind: |tcx, ()| CStore::from_tcx(tcx).allocator_kind(),
         alloc_error_handler_kind: |tcx, ()| CStore::from_tcx(tcx).alloc_error_handler_kind(),
         is_private_dep: |_tcx, LocalCrate| false,
@@ -513,8 +514,9 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
             tcx.untracked().cstore.freeze();
             tcx.arena.alloc_from_iter(CStore::from_tcx(tcx).iter_crate_data().map(|(cnum, _)| cnum))
         },
-        ..*providers
+        ..providers.queries
     };
+    provide_extern(&mut providers.extern_queries);
 }
 
 impl CStore {

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -21,10 +21,10 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::mir;
-use rustc_middle::query::Providers;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{self, ReprOptions, Ty, UnusedGenericParams};
 use rustc_middle::ty::{DeducedParamAttrs, GeneratorDiagnosticData, ParameterizedOverTcx, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_serialize::opaque::FileEncoder;
 use rustc_session::config::SymbolManglingVersion;
 use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
@@ -38,7 +38,6 @@ use rustc_target::spec::{PanicStrategy, TargetTriple};
 use std::marker::PhantomData;
 use std::num::NonZeroUsize;
 
-pub use decoder::provide_extern;
 use decoder::DecodeContext;
 pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
 use encoder::EncodeContext;

compiler/rustc_middle/src/hooks/mod.rs

@@ -0,0 +1,65 @@
+use crate::mir;
+use crate::query::TyCtxtAt;
+use crate::ty::{Ty, TyCtxt};
+use rustc_span::DUMMY_SP;
+
+macro_rules! declare_hooks {
+    ($($(#[$attr:meta])*hook $name:ident($($arg:ident: $K:ty),*) -> $V:ty;)*) => {
+
+        impl<'tcx> TyCtxt<'tcx> {
+            $(
+            $(#[$attr])*
+            #[inline(always)]
+            #[must_use]
+            pub fn $name(self, $($arg: $K,)*) -> $V
+            {
+                self.at(DUMMY_SP).$name($($arg,)*)
+            }
+            )*
+        }
+
+        impl<'tcx> TyCtxtAt<'tcx> {
+            $(
+            $(#[$attr])*
+            #[inline(always)]
+            #[must_use]
+            #[instrument(level = "debug", skip(self), ret)]
+            pub fn $name(self, $($arg: $K,)*) -> $V
+            {
+                (self.tcx.hooks.$name)(self, $($arg,)*)
+            }
+            )*
+        }
+
+        pub struct Providers {
+            $(pub $name: for<'tcx> fn(
+                TyCtxtAt<'tcx>,
+                $($arg: $K,)*
+            ) -> $V,)*
+        }
+
+        impl Default for Providers {
+            fn default() -> Self {
+                Providers {
+                    $($name: |_, $($arg,)*| bug!(
+                        "`tcx.{}{:?}` cannot be called as `{}` was never assigned to a provider function.\n",
+                        stringify!($name),
+                        ($($arg,)*),
+                        stringify!($name),
+                    ),)*
+                }
+            }
+        }
+
+        impl Copy for Providers {}
+        impl Clone for Providers {
+            fn clone(&self) -> Self { *self }
+        }
+    };
+}
+
+declare_hooks! {
+    /// Tries to destructure an `mir::Const` ADT or array into its variant index
+    /// and its field values. This should only be used for pretty printing.
+    hook try_destructure_mir_constant_for_diagnostics(val: mir::ConstValue<'tcx>, ty: Ty<'tcx>) -> Option<mir::DestructuredConstant<'tcx>>;
+}

compiler/rustc_middle/src/lib.rs

@@ -89,6 +89,7 @@ mod macros;
 pub mod arena;
 pub mod error;
 pub mod hir;
+pub mod hooks;
 pub mod infer;
 pub mod lint;
 pub mod metadata;

compiler/rustc_middle/src/mir/pretty.rs

@@ -1691,7 +1691,7 @@ fn pretty_print_const_value_tcx<'tcx>(
         (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_non_region_param() => {
             let ct = tcx.lift(ct).unwrap();
             let ty = tcx.lift(ty).unwrap();
-            if let Some(contents) = tcx.try_destructure_mir_constant_for_diagnostics((ct, ty)) {
+            if let Some(contents) = tcx.try_destructure_mir_constant_for_diagnostics(ct, ty) {
                 let fields: Vec<(ConstValue<'_>, Ty<'_>)> = contents.fields.to_vec();
                 match *ty.kind() {
                     ty::Array(..) => {