diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 4ef21449d216e..7cef0708329d0 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -357,7 +357,7 @@ fn is_unreachable_local_definition_provider(tcx: TyCtxt<'_>, def_id: LocalDefId)
     !tcx.reachable_set(()).contains(&def_id)
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.reachable_non_generics = reachable_non_generics_provider;
     providers.is_reachable_non_generic = is_reachable_non_generic_provider_local;
     providers.exported_symbols = exported_symbols_provider_local;
@@ -367,7 +367,7 @@ pub fn provide(providers: &mut Providers) {
     providers.wasm_import_module_map = wasm_import_module_map;
 }
 
-pub fn provide_extern(providers: &mut Providers) {
+pub const fn provide_extern(providers: &mut Providers) {
     providers.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
     providers.upstream_monomorphizations_for = upstream_monomorphizations_for_provider;
 }
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index be2bf8b199724..b63ac073e45e3 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -849,7 +849,7 @@ impl CrateInfo {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.backend_optimization_level = |tcx, cratenum| {
         let for_speed = match tcx.sess.opts.optimize {
             // If globally no optimisation is done, #[optimize] has no effect.
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index b6ee70c419b16..d670d31187c2c 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -5,6 +5,8 @@
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![feature(associated_type_bounds)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).
@@ -161,13 +163,13 @@ pub struct CodegenResults {
     pub crate_info: CrateInfo,
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     crate::back::symbol_export::provide(providers);
     crate::base::provide(providers);
     crate::target_features::provide(providers);
 }
 
-pub fn provide_extern(providers: &mut Providers) {
+pub const fn provide_extern(providers: &mut Providers) {
     crate::back::symbol_export::provide_extern(providers);
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index c89d42ecc58ac..cdf1d22ba0494 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -245,7 +245,7 @@ pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Opt
     }
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     providers.supported_target_features = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
         if tcx.sess.opts.actually_rustdoc {
diff --git a/compiler/rustc_interface/src/lib.rs b/compiler/rustc_interface/src/lib.rs
index c7424b9e2a120..addcdc1353795 100644
--- a/compiler/rustc_interface/src/lib.rs
+++ b/compiler/rustc_interface/src/lib.rs
@@ -1,5 +1,7 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![feature(internal_output_capture)]
 #![feature(nll)]
 #![feature(once_cell)]
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index e568b5ca50110..d14c5c23d9496 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -45,7 +45,6 @@ use std::any::Any;
 use std::cell::RefCell;
 use std::ffi::OsString;
 use std::io::{self, BufWriter, Write};
-use std::lazy::SyncLazy;
 use std::marker::PhantomPinned;
 use std::path::PathBuf;
 use std::pin::Pin;
@@ -737,35 +736,35 @@ pub fn prepare_outputs(
     Ok(outputs)
 }
 
-pub static DEFAULT_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
-    let providers = &mut Providers::default();
+pub static DEFAULT_QUERY_PROVIDERS: Providers = {
+    let mut providers = Providers::default();
     providers.analysis = analysis;
-    proc_macro_decls::provide(providers);
-    plugin::build::provide(providers);
-    rustc_middle::hir::provide(providers);
-    mir::provide(providers);
-    mir_build::provide(providers);
-    rustc_privacy::provide(providers);
-    typeck::provide(providers);
-    ty::provide(providers);
-    traits::provide(providers);
-    rustc_passes::provide(providers);
-    rustc_resolve::provide(providers);
-    rustc_traits::provide(providers);
-    rustc_ty_utils::provide(providers);
-    rustc_metadata::provide(providers);
-    rustc_lint::provide(providers);
-    rustc_symbol_mangling::provide(providers);
-    rustc_codegen_ssa::provide(providers);
-    *providers
-});
-
-pub static DEFAULT_EXTERN_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
-    let mut extern_providers = *DEFAULT_QUERY_PROVIDERS;
+    proc_macro_decls::provide(&mut providers);
+    plugin::build::provide(&mut providers);
+    rustc_middle::hir::provide(&mut providers);
+    mir::provide(&mut providers);
+    mir_build::provide(&mut providers);
+    rustc_privacy::provide(&mut providers);
+    typeck::provide(&mut providers);
+    ty::provide(&mut providers);
+    traits::provide(&mut providers);
+    rustc_passes::provide(&mut providers);
+    rustc_resolve::provide(&mut providers);
+    rustc_traits::provide(&mut providers);
+    rustc_ty_utils::provide(&mut providers);
+    rustc_metadata::provide(&mut providers);
+    rustc_lint::provide(&mut providers);
+    rustc_symbol_mangling::provide(&mut providers);
+    rustc_codegen_ssa::provide(&mut providers);
+    providers
+};
+
+pub static DEFAULT_EXTERN_QUERY_PROVIDERS: Providers = {
+    let mut extern_providers = DEFAULT_QUERY_PROVIDERS;
     rustc_metadata::provide_extern(&mut extern_providers);
     rustc_codegen_ssa::provide_extern(&mut extern_providers);
     extern_providers
-});
+};
 
 pub struct QueryContext<'tcx> {
     gcx: &'tcx GlobalCtxt<'tcx>,
@@ -808,10 +807,10 @@ 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;
+    let mut local_providers = DEFAULT_QUERY_PROVIDERS;
     codegen_backend.provide(&mut local_providers);
 
-    let mut extern_providers = *DEFAULT_EXTERN_QUERY_PROVIDERS;
+    let mut extern_providers = DEFAULT_EXTERN_QUERY_PROVIDERS;
     codegen_backend.provide(&mut extern_providers);
     codegen_backend.provide_extern(&mut extern_providers);
 
diff --git a/compiler/rustc_interface/src/proc_macro_decls.rs b/compiler/rustc_interface/src/proc_macro_decls.rs
index 88cf6275ebbd0..fa7fffe6b0762 100644
--- a/compiler/rustc_interface/src/proc_macro_decls.rs
+++ b/compiler/rustc_interface/src/proc_macro_decls.rs
@@ -32,6 +32,6 @@ impl<'v> ItemLikeVisitor<'v> for Finder<'_> {
     fn visit_foreign_item(&mut self, _foreign_item: &hir::ForeignItem<'_>) {}
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { proc_macro_decls_static, ..*providers };
 }
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index bc6956f579783..acbf479dc76b9 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -698,6 +698,6 @@ impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'_, 'tcx> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.lint_levels = lint_levels;
 }
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 28b60603a2dbb..11300cae54660 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -37,6 +37,8 @@
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(control_flow_enum)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -96,7 +98,7 @@ pub use rustc_session::lint::Level::{self, *};
 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 pub use rustc_session::lint::{LintArray, LintPass};
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     levels::provide(providers);
     *providers = Providers { lint_mod, ..*providers };
 }
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 2c9bad7e5cedb..09af7973189cc 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -8,6 +8,8 @@
 #![feature(min_specialization)]
 #![feature(try_blocks)]
 #![feature(never_type)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 extern crate proc_macro;
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 68cf4304b7165..d60d158c54648 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -30,7 +30,7 @@ use std::any::Any;
 macro_rules! provide {
     (<$lt:tt> $tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
       $($name:ident => $compute:block)*) => {
-        pub fn provide_extern(providers: &mut Providers) {
+        pub const fn provide_extern(providers: &mut Providers) {
             $(fn $name<$lt>(
                 $tcx: TyCtxt<$lt>,
                 def_id_arg: ty::query::query_keys::$name<$lt>,
@@ -235,7 +235,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     expn_that_defined => { cdata.get_expn_that_defined(def_id.index, tcx.sess) }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const 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
diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index 087f772c812bd..15840c3653a07 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -129,7 +129,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.parent_module_from_def_id = |tcx, id| {
         let hir = tcx.hir();
         hir.local_def_id(hir.get_module_parent_node(hir.local_def_id_to_hir_id(id)))
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 57f507290e894..d1c9525375bf0 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -49,6 +49,8 @@
 #![feature(iter_zip)]
 #![feature(thread_local_const_init)]
 #![feature(try_reserve)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "512"]
 
 #[macro_use]
diff --git a/compiler/rustc_middle/src/middle/limits.rs b/compiler/rustc_middle/src/middle/limits.rs
index c4bfd0ebb2fde..cf73895f39de7 100644
--- a/compiler/rustc_middle/src/middle/limits.rs
+++ b/compiler/rustc_middle/src/middle/limits.rs
@@ -18,7 +18,7 @@ use rustc_span::symbol::{sym, Symbol};
 
 use std::num::IntErrorKind;
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     providers.limits = |tcx, ()| Limits {
         recursion_limit: get_recursion_limit(tcx.hir().krate_attrs(), tcx.sess),
         move_size_limit: get_limit(tcx.hir().krate_attrs(), tcx.sess, sym::move_size_limit, 0),
diff --git a/compiler/rustc_middle/src/middle/mod.rs b/compiler/rustc_middle/src/middle/mod.rs
index b370ec152e8ec..bba27fc635269 100644
--- a/compiler/rustc_middle/src/middle/mod.rs
+++ b/compiler/rustc_middle/src/middle/mod.rs
@@ -33,6 +33,6 @@ pub mod region;
 pub mod resolve_lifetime;
 pub mod stability;
 
-pub fn provide(providers: &mut crate::ty::query::Providers) {
+pub const fn provide(providers: &mut crate::ty::query::Providers) {
     limits::provide(providers);
 }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 9c98592c86518..5a4f5dbb660c9 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2819,7 +2819,7 @@ fn ptr_eq<T, U>(t: *const T, u: *const U) -> bool {
     t as *const () == u as *const ()
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     providers.in_scope_traits_map = |tcx, id| tcx.hir_crate(()).trait_map.get(&id);
     providers.module_exports = |tcx, id| tcx.gcx.export_map.get(&id).map(|v| &v[..]);
     providers.crate_name = |tcx, id| {
diff --git a/compiler/rustc_middle/src/ty/erase_regions.rs b/compiler/rustc_middle/src/ty/erase_regions.rs
index 759d1a017aa2a..6f3ae7995f2e4 100644
--- a/compiler/rustc_middle/src/ty/erase_regions.rs
+++ b/compiler/rustc_middle/src/ty/erase_regions.rs
@@ -2,7 +2,7 @@ use crate::mir;
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::ty::{self, Ty, TyCtxt, TypeFlags};
 
-pub(super) fn provide(providers: &mut ty::query::Providers) {
+pub(super) const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers { erase_regions_ty, ..*providers };
 }
 
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index dbb5064c4f546..fa67151927e3b 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -242,7 +242,7 @@ fn layout_raw<'tcx>(
     })
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers { layout_raw, ..*providers };
 }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 156e860e1a3fb..4384e4b61ff52 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1978,7 +1978,7 @@ pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
     }
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     context::provide(providers);
     erase_regions::provide(providers);
     layout::provide(providers);
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index cb326996111b7..c666a577ecbd5 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2348,6 +2348,6 @@ fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> {
     map
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers { trimmed_def_paths, ..*providers };
 }
diff --git a/compiler/rustc_middle/src/ty/query/mod.rs b/compiler/rustc_middle/src/ty/query/mod.rs
index 2ed9ede8951c9..5df28d3116e3d 100644
--- a/compiler/rustc_middle/src/ty/query/mod.rs
+++ b/compiler/rustc_middle/src/ty/query/mod.rs
@@ -215,8 +215,11 @@ macro_rules! define_callbacks {
             ) -> query_values::$name<'tcx>,)*
         }
 
-        impl Default for Providers {
-            fn default() -> Self {
+
+        // FIXME: Make this an `impl const Default for Providers`
+        // when `const_trait_impl` is no longer incomplete
+        impl Providers {
+            pub const fn default() -> Self {
                 Providers {
                     $($name: |_, key| bug!(
                         "`tcx.{}({:?})` unsupported by its crate; \
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 485be4c9987bd..a510e9ca6aeb0 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1084,6 +1084,6 @@ pub fn normalize_opaque_types(
     val.fold_with(&mut visitor)
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers { normalize_opaque_types, ..*providers }
 }
diff --git a/compiler/rustc_middle/src/util/bug.rs b/compiler/rustc_middle/src/util/bug.rs
index 791d5060fe5c7..9144a3b1abdb9 100644
--- a/compiler/rustc_middle/src/util/bug.rs
+++ b/compiler/rustc_middle/src/util/bug.rs
@@ -48,6 +48,6 @@ pub fn trigger_delay_span_bug(tcx: TyCtxt<'_>, key: rustc_hir::def_id::DefId) {
     );
 }
 
-pub fn provide(providers: &mut crate::ty::query::Providers) {
+pub const fn provide(providers: &mut crate::ty::query::Providers) {
     *providers = crate::ty::query::Providers { trigger_delay_span_bug, ..*providers };
 }
diff --git a/compiler/rustc_mir/src/borrow_check/mod.rs b/compiler/rustc_mir/src/borrow_check/mod.rs
index 36eb8a4baa830..ced8a91332a62 100644
--- a/compiler/rustc_mir/src/borrow_check/mod.rs
+++ b/compiler/rustc_mir/src/borrow_check/mod.rs
@@ -82,7 +82,7 @@ crate struct Upvar<'tcx> {
 
 const DEREF_PROJECTION: &[PlaceElem<'_>; 1] = &[ProjectionElem::Deref];
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers {
         mir_borrowck: |tcx, did| {
             if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) {
diff --git a/compiler/rustc_mir/src/const_eval/fn_queries.rs b/compiler/rustc_mir/src/const_eval/fn_queries.rs
index 40419a4d201ac..1493f0d298658 100644
--- a/compiler/rustc_mir/src/const_eval/fn_queries.rs
+++ b/compiler/rustc_mir/src/const_eval/fn_queries.rs
@@ -102,7 +102,7 @@ fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
         }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers {
         is_const_fn_raw,
         is_const_impl_raw: |tcx, def_id| is_const_impl_raw(tcx, def_id.expect_local()),
diff --git a/compiler/rustc_mir/src/lib.rs b/compiler/rustc_mir/src/lib.rs
index a58ded9cfd3a4..cc143b25312d7 100644
--- a/compiler/rustc_mir/src/lib.rs
+++ b/compiler/rustc_mir/src/lib.rs
@@ -30,6 +30,8 @@ Rust MIR: a lowered representation of Rust.
 #![feature(once_cell)]
 #![feature(control_flow_enum)]
 #![feature(try_reserve)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -48,7 +50,7 @@ pub mod util;
 
 use rustc_middle::ty::query::Providers;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     borrow_check::provide(providers);
     const_eval::provide(providers);
     shim::provide(providers);
diff --git a/compiler/rustc_mir/src/monomorphize/partitioning/mod.rs b/compiler/rustc_mir/src/monomorphize/partitioning/mod.rs
index 6ed0ab8be41ee..6eb55f9ce5798 100644
--- a/compiler/rustc_mir/src/monomorphize/partitioning/mod.rs
+++ b/compiler/rustc_mir/src/monomorphize/partitioning/mod.rs
@@ -448,7 +448,7 @@ fn codegened_and_inlined_items<'tcx>(tcx: TyCtxt<'tcx>, (): ()) -> &'tcx DefIdSe
     tcx.arena.alloc(result)
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.collect_and_partition_mono_items = collect_and_partition_mono_items;
     providers.codegened_and_inlined_items = codegened_and_inlined_items;
 
diff --git a/compiler/rustc_mir/src/monomorphize/polymorphize.rs b/compiler/rustc_mir/src/monomorphize/polymorphize.rs
index 30e758c7fdf05..e7c64d2bf58b0 100644
--- a/compiler/rustc_mir/src/monomorphize/polymorphize.rs
+++ b/compiler/rustc_mir/src/monomorphize/polymorphize.rs
@@ -23,7 +23,7 @@ use std::convert::TryInto;
 use std::ops::ControlFlow;
 
 /// Provide implementations of queries relating to polymorphization analysis.
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.unused_generic_params = unused_generic_params;
 }
 
diff --git a/compiler/rustc_mir/src/shim.rs b/compiler/rustc_mir/src/shim.rs
index 796d024771d7f..c1528722a2009 100644
--- a/compiler/rustc_mir/src/shim.rs
+++ b/compiler/rustc_mir/src/shim.rs
@@ -23,7 +23,7 @@ use crate::util::elaborate_drops::{self, DropElaborator, DropFlagMode, DropStyle
 use crate::util::expand_aggregate;
 use crate::util::patch::MirPatch;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.mir_shims = make_shim;
 }
 
diff --git a/compiler/rustc_mir/src/transform/check_packed_ref.rs b/compiler/rustc_mir/src/transform/check_packed_ref.rs
index 13b7221046bda..e4eac67220010 100644
--- a/compiler/rustc_mir/src/transform/check_packed_ref.rs
+++ b/compiler/rustc_mir/src/transform/check_packed_ref.rs
@@ -9,7 +9,7 @@ use rustc_span::symbol::sym;
 use crate::transform::MirPass;
 use crate::util;
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { unsafe_derive_on_repr_packed, ..*providers };
 }
 
diff --git a/compiler/rustc_mir/src/transform/check_unsafety.rs b/compiler/rustc_mir/src/transform/check_unsafety.rs
index 1ff9bd1572108..074fe62d8bb8f 100644
--- a/compiler/rustc_mir/src/transform/check_unsafety.rs
+++ b/compiler/rustc_mir/src/transform/check_unsafety.rs
@@ -372,7 +372,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
     }
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers {
         unsafety_check_result: |tcx, def_id| {
             if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
diff --git a/compiler/rustc_mir/src/transform/coverage/query.rs b/compiler/rustc_mir/src/transform/coverage/query.rs
index 760f16eae6b1f..cb276a06b8c39 100644
--- a/compiler/rustc_mir/src/transform/coverage/query.rs
+++ b/compiler/rustc_mir/src/transform/coverage/query.rs
@@ -7,7 +7,7 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::def_id::DefId;
 
 /// A `query` provider for retrieving coverage information injected into MIR.
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     providers.coverageinfo = |tcx, def_id| coverageinfo(tcx, def_id);
     providers.covered_file_name = |tcx, def_id| covered_file_name(tcx, def_id);
     providers.covered_code_regions = |tcx, def_id| covered_code_regions(tcx, def_id);
diff --git a/compiler/rustc_mir/src/transform/mod.rs b/compiler/rustc_mir/src/transform/mod.rs
index 5c201594ddd89..346dcbdc3dfc2 100644
--- a/compiler/rustc_mir/src/transform/mod.rs
+++ b/compiler/rustc_mir/src/transform/mod.rs
@@ -58,7 +58,7 @@ pub mod validate;
 
 pub use rustc_middle::mir::MirSource;
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     self::check_unsafety::provide(providers);
     self::check_packed_ref::provide(providers);
     *providers = Providers {
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index d2992f0bf186e..733cd68e7da5a 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -9,6 +9,8 @@
 #![feature(iter_zip)]
 #![feature(once_cell)]
 #![feature(min_specialization)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -23,7 +25,7 @@ pub mod thir;
 
 use rustc_middle::ty::query::Providers;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.check_match = thir::pattern::check_match;
     providers.lit_to_const = thir::constant::lit_to_const;
     providers.mir_built = build::mir_built;
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index d0795841c5359..3b2a774e84f74 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1626,6 +1626,6 @@ fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     }
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_attrs, ..*providers };
 }
diff --git a/compiler/rustc_passes/src/check_const.rs b/compiler/rustc_passes/src/check_const.rs
index d783852aacadd..a2919267e3d4c 100644
--- a/compiler/rustc_passes/src/check_const.rs
+++ b/compiler/rustc_passes/src/check_const.rs
@@ -63,7 +63,7 @@ fn check_mod_const_bodies(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut CheckConstTraitVisitor::new(tcx));
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_const_bodies, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/diagnostic_items.rs b/compiler/rustc_passes/src/diagnostic_items.rs
index ddcc6fc123f7b..43424d1dc272d 100644
--- a/compiler/rustc_passes/src/diagnostic_items.rs
+++ b/compiler/rustc_passes/src/diagnostic_items.rs
@@ -130,7 +130,7 @@ fn all_diagnostic_items<'tcx>(tcx: TyCtxt<'tcx>, (): ()) -> FxHashMap<Symbol, De
     collector
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.diagnostic_items = diagnostic_items;
     providers.all_diagnostic_items = all_diagnostic_items;
 }
diff --git a/compiler/rustc_passes/src/entry.rs b/compiler/rustc_passes/src/entry.rs
index 34ea5e9abd4d5..1a125102dc7c7 100644
--- a/compiler/rustc_passes/src/entry.rs
+++ b/compiler/rustc_passes/src/entry.rs
@@ -239,6 +239,6 @@ fn no_main_err(tcx: TyCtxt<'_>, visitor: &EntryContext<'_, '_>) {
     err.emit();
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { entry_fn, ..*providers };
 }
diff --git a/compiler/rustc_passes/src/intrinsicck.rs b/compiler/rustc_passes/src/intrinsicck.rs
index 012d97ef106c7..cb26debfdb00d 100644
--- a/compiler/rustc_passes/src/intrinsicck.rs
+++ b/compiler/rustc_passes/src/intrinsicck.rs
@@ -18,7 +18,7 @@ fn check_mod_intrinsics(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut ItemVisitor { tcx }.as_deep_visitor());
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_intrinsics, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index 3a88d1932a80a..012f882a3bc84 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -324,6 +324,6 @@ fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
     items
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.get_lang_items = get_lang_items;
 }
diff --git a/compiler/rustc_passes/src/lib.rs b/compiler/rustc_passes/src/lib.rs
index cadb8d2358060..7205fb2a7cb81 100644
--- a/compiler/rustc_passes/src/lib.rs
+++ b/compiler/rustc_passes/src/lib.rs
@@ -11,6 +11,8 @@
 #![feature(nll)]
 #![feature(min_specialization)]
 #![feature(try_blocks)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -40,7 +42,7 @@ pub mod stability;
 mod upvars;
 mod weak_lang_items;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     check_attr::provide(providers);
     check_const::provide(providers);
     diagnostic_items::provide(providers);
diff --git a/compiler/rustc_passes/src/lib_features.rs b/compiler/rustc_passes/src/lib_features.rs
index 363a6417f99d3..ded54c94d2bb6 100644
--- a/compiler/rustc_passes/src/lib_features.rs
+++ b/compiler/rustc_passes/src/lib_features.rs
@@ -136,6 +136,6 @@ fn get_lib_features(tcx: TyCtxt<'_>, (): ()) -> LibFeatures {
     collector.lib_features
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.get_lib_features = get_lib_features;
 }
diff --git a/compiler/rustc_passes/src/liveness.rs b/compiler/rustc_passes/src/liveness.rs
index 4ceefa17bcf3d..ae921b995c655 100644
--- a/compiler/rustc_passes/src/liveness.rs
+++ b/compiler/rustc_passes/src/liveness.rs
@@ -144,7 +144,7 @@ fn check_mod_liveness(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut IrMaps::new(tcx).as_deep_visitor());
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_liveness, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/loops.rs b/compiler/rustc_passes/src/loops.rs
index 4bfac1b72983e..464b843ccfb3c 100644
--- a/compiler/rustc_passes/src/loops.rs
+++ b/compiler/rustc_passes/src/loops.rs
@@ -36,7 +36,7 @@ fn check_mod_loops(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     );
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_loops, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/naked_functions.rs b/compiler/rustc_passes/src/naked_functions.rs
index 89bc2e1a9870f..73d79af3bdfc1 100644
--- a/compiler/rustc_passes/src/naked_functions.rs
+++ b/compiler/rustc_passes/src/naked_functions.rs
@@ -19,7 +19,7 @@ fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     );
 }
 
-crate fn provide(providers: &mut Providers) {
+crate const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_naked_functions, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/reachable.rs b/compiler/rustc_passes/src/reachable.rs
index 0b3227abb5f8b..f45298762e022 100644
--- a/compiler/rustc_passes/src/reachable.rs
+++ b/compiler/rustc_passes/src/reachable.rs
@@ -432,6 +432,6 @@ fn reachable_set<'tcx>(tcx: TyCtxt<'tcx>, (): ()) -> FxHashSet<LocalDefId> {
     reachable_context.reachable_symbols
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { reachable_set, ..*providers };
 }
diff --git a/compiler/rustc_passes/src/region.rs b/compiler/rustc_passes/src/region.rs
index c133f1a041719..6a1454708b81c 100644
--- a/compiler/rustc_passes/src/region.rs
+++ b/compiler/rustc_passes/src/region.rs
@@ -840,6 +840,6 @@ fn region_scope_tree(tcx: TyCtxt<'_>, def_id: DefId) -> &ScopeTree {
     tcx.arena.alloc(scope_tree)
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { region_scope_tree, ..*providers };
 }
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index cd8dd6984d5b9..3498f1ea8769e 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -750,7 +750,7 @@ fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
 }
 
-pub(crate) fn provide(providers: &mut Providers) {
+pub(crate) const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_unstable_api_usage, stability_index, ..*providers };
 }
 
diff --git a/compiler/rustc_passes/src/upvars.rs b/compiler/rustc_passes/src/upvars.rs
index 91b8ae07637df..2e31ec530f38d 100644
--- a/compiler/rustc_passes/src/upvars.rs
+++ b/compiler/rustc_passes/src/upvars.rs
@@ -9,7 +9,7 @@ use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::Span;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.upvars_mentioned = |tcx, def_id| {
         if !tcx.is_closure(def_id) {
             return None;
diff --git a/compiler/rustc_plugin_impl/src/build.rs b/compiler/rustc_plugin_impl/src/build.rs
index b95c4a720195a..2b3cf34d3314f 100644
--- a/compiler/rustc_plugin_impl/src/build.rs
+++ b/compiler/rustc_plugin_impl/src/build.rs
@@ -52,6 +52,6 @@ fn plugin_registrar_fn(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
     Some(def_id)
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { plugin_registrar_fn, ..*providers };
 }
diff --git a/compiler/rustc_plugin_impl/src/lib.rs b/compiler/rustc_plugin_impl/src/lib.rs
index 5bf4d300e9e54..544cb635d6b9d 100644
--- a/compiler/rustc_plugin_impl/src/lib.rs
+++ b/compiler/rustc_plugin_impl/src/lib.rs
@@ -8,6 +8,8 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(nll)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 use rustc_lint::LintStore;
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 5a79a9cc6ecfd..d03ca41668bec 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -4,6 +4,8 @@
 #![feature(control_flow_enum)]
 #![feature(try_blocks)]
 #![feature(associated_type_defaults)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 use rustc_attr as attr;
@@ -2019,7 +2021,7 @@ impl<'tcx> Visitor<'tcx> for PrivateItemsInPublicInterfacesVisitor<'tcx> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers {
         visibility,
         privacy_access_levels,
diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index ca7cdc4caf505..c3853fa863bcf 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -369,7 +369,7 @@ type ScopeRef<'a> = &'a Scope<'a>;
 
 const ROOT_SCOPE: ScopeRef<'static> = &Scope::Root;
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         resolve_lifetimes_trait_definition,
         resolve_lifetimes,
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 559a996708624..077c0fccbee8b 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -15,6 +15,8 @@
 #![feature(format_args_capture)]
 #![feature(iter_zip)]
 #![feature(nll)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 #![allow(rustdoc::private_intra_doc_links)]
 
@@ -3466,6 +3468,6 @@ impl CrateLint {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     late::lifetimes::provide(providers);
 }
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
index ba59ff96f6554..c87c9aa47f7fd 100644
--- a/compiler/rustc_symbol_mangling/src/lib.rs
+++ b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -91,6 +91,8 @@
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(in_band_lifetimes)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -123,7 +125,7 @@ pub fn symbol_name_for_instance_in_crate(
     compute_symbol_name(tcx, instance, || instantiating_crate)
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { symbol_name: symbol_name_provider, ..*providers };
 }
 
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index e932b1bca7c7b..53754ebbe8733 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -20,6 +20,8 @@
 #![feature(never_type)]
 #![feature(crate_visibility_modifier)]
 #![feature(control_flow_enum)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "512"] // For rustdoc
 
 #[macro_use]
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 3a80e720e8c4b..05dc8115116e6 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -541,7 +541,7 @@ fn vtable_trait_first_method_offset<'tcx>(
     vtable_base
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     object_safety::provide(providers);
     structural_match::provide(providers);
     *providers = ty::query::Providers {
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 7ebef7f8883ae..4b4ae64744958 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -879,6 +879,6 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
         .is_break()
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers { object_safety_violations, ..*providers };
 }
diff --git a/compiler/rustc_trait_selection/src/traits/structural_match.rs b/compiler/rustc_trait_selection/src/traits/structural_match.rs
index 3d20a8d5cf336..35d3023bb9b14 100644
--- a/compiler/rustc_trait_selection/src/traits/structural_match.rs
+++ b/compiler/rustc_trait_selection/src/traits/structural_match.rs
@@ -240,7 +240,7 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     providers.has_structural_eq_impls = |tcx, ty| {
         tcx.infer_ctxt().enter(|infcx| {
             let cause = ObligationCause::dummy();
diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
index b7275bac19048..5e8217c2dd2d1 100644
--- a/compiler/rustc_traits/src/chalk/mod.rs
+++ b/compiler/rustc_traits/src/chalk/mod.rs
@@ -28,7 +28,7 @@ use crate::chalk::lowering::{
 
 use chalk_solve::Solution;
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers { evaluate_goal, ..*p };
 }
 
diff --git a/compiler/rustc_traits/src/dropck_outlives.rs b/compiler/rustc_traits/src/dropck_outlives.rs
index 4a41dfe01431e..7328bf0d98d74 100644
--- a/compiler/rustc_traits/src/dropck_outlives.rs
+++ b/compiler/rustc_traits/src/dropck_outlives.rs
@@ -17,7 +17,7 @@ use rustc_trait_selection::traits::{
     Normalized, ObligationCause, TraitEngine, TraitEngineExt as _,
 };
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p };
 }
 
diff --git a/compiler/rustc_traits/src/evaluate_obligation.rs b/compiler/rustc_traits/src/evaluate_obligation.rs
index 2404b7ff4b54a..94a8d8c741184 100644
--- a/compiler/rustc_traits/src/evaluate_obligation.rs
+++ b/compiler/rustc_traits/src/evaluate_obligation.rs
@@ -7,7 +7,7 @@ use rustc_trait_selection::traits::{
     EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
 };
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers { evaluate_obligation, ..*p };
 }
 
diff --git a/compiler/rustc_traits/src/implied_outlives_bounds.rs b/compiler/rustc_traits/src/implied_outlives_bounds.rs
index 90ba90259c32b..c026a979835c0 100644
--- a/compiler/rustc_traits/src/implied_outlives_bounds.rs
+++ b/compiler/rustc_traits/src/implied_outlives_bounds.rs
@@ -18,7 +18,7 @@ use rustc_trait_selection::traits::FulfillmentContext;
 use rustc_trait_selection::traits::TraitEngine;
 use smallvec::{smallvec, SmallVec};
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers { implied_outlives_bounds, ..*p };
 }
 
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
index d0b05beb4e63c..dfa04d58aab97 100644
--- a/compiler/rustc_traits/src/lib.rs
+++ b/compiler/rustc_traits/src/lib.rs
@@ -4,6 +4,8 @@
 #![feature(crate_visibility_modifier)]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -21,7 +23,7 @@ mod type_op;
 
 use rustc_middle::ty::query::Providers;
 
-pub fn provide(p: &mut Providers) {
+pub const fn provide(p: &mut Providers) {
     dropck_outlives::provide(p);
     evaluate_obligation::provide(p);
     implied_outlives_bounds::provide(p);
diff --git a/compiler/rustc_traits/src/normalize_erasing_regions.rs b/compiler/rustc_traits/src/normalize_erasing_regions.rs
index 5ad0684fe6ee2..af06f1fd740e5 100644
--- a/compiler/rustc_traits/src/normalize_erasing_regions.rs
+++ b/compiler/rustc_traits/src/normalize_erasing_regions.rs
@@ -6,7 +6,7 @@ use rustc_trait_selection::traits::query::normalize::AtExt;
 use rustc_trait_selection::traits::{Normalized, ObligationCause};
 use std::sync::atomic::Ordering;
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers {
         normalize_generic_arg_after_erasing_regions: |tcx, goal| {
             debug!("normalize_generic_arg_after_erasing_regions(goal={:#?})", goal);
diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs
index a8e376838e218..373a20502977e 100644
--- a/compiler/rustc_traits/src/normalize_projection_ty.rs
+++ b/compiler/rustc_traits/src/normalize_projection_ty.rs
@@ -10,7 +10,7 @@ use rustc_trait_selection::traits::query::{
 use rustc_trait_selection::traits::{self, ObligationCause, SelectionContext};
 use std::sync::atomic::Ordering;
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers { normalize_projection_ty, ..*p };
 }
 
diff --git a/compiler/rustc_traits/src/type_op.rs b/compiler/rustc_traits/src/type_op.rs
index 6304f696b00fa..8b556094c3f09 100644
--- a/compiler/rustc_traits/src/type_op.rs
+++ b/compiler/rustc_traits/src/type_op.rs
@@ -21,7 +21,7 @@ use rustc_trait_selection::traits::query::{Fallible, NoSolution};
 use rustc_trait_selection::traits::{Normalized, Obligation, ObligationCause, TraitEngine};
 use std::fmt;
 
-crate fn provide(p: &mut Providers) {
+crate const fn provide(p: &mut Providers) {
     *p = Providers {
         type_op_ascribe_user_type,
         type_op_eq,
diff --git a/compiler/rustc_ty_utils/src/common_traits.rs b/compiler/rustc_ty_utils/src/common_traits.rs
index cedc84d97c2d9..ba8c65bb7ffc1 100644
--- a/compiler/rustc_ty_utils/src/common_traits.rs
+++ b/compiler/rustc_ty_utils/src/common_traits.rs
@@ -40,7 +40,7 @@ fn is_item_raw<'tcx>(
     })
 }
 
-pub(crate) fn provide(providers: &mut ty::query::Providers) {
+pub(crate) const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         is_copy_raw,
         is_sized_raw,
diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs
index 469ac04e54515..aa90ce59fcb91 100644
--- a/compiler/rustc_ty_utils/src/instance.rs
+++ b/compiler/rustc_ty_utils/src/instance.rs
@@ -385,7 +385,7 @@ fn resolve_associated_item<'tcx>(
     })
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers =
         ty::query::Providers { resolve_instance, resolve_instance_of_const_arg, ..*providers };
 }
diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs
index 313571274c3de..7d8b563f201c5 100644
--- a/compiler/rustc_ty_utils/src/lib.rs
+++ b/compiler/rustc_ty_utils/src/lib.rs
@@ -9,6 +9,8 @@
 #![feature(half_open_range_patterns)]
 #![feature(exclusive_range_pattern)]
 #![feature(nll)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -24,7 +26,7 @@ mod needs_drop;
 pub mod representability;
 mod ty;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     common_traits::provide(providers);
     needs_drop::provide(providers);
     ty::provide(providers);
diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs
index d837af85d58ae..87aa76461a125 100644
--- a/compiler/rustc_ty_utils/src/needs_drop.rs
+++ b/compiler/rustc_ty_utils/src/needs_drop.rs
@@ -218,7 +218,7 @@ fn adt_significant_drop_tys(
     adt_drop_tys_helper(tcx, def_id, adt_has_dtor)
 }
 
-pub(crate) fn provide(providers: &mut ty::query::Providers) {
+pub(crate) const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         needs_drop_raw,
         has_significant_drop_raw,
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
index ffde9b79265a5..b3cb1e24c5914 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -521,7 +521,7 @@ pub fn conservative_is_privately_uninhabited_raw<'tcx>(
     }
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         asyncness,
         associated_item,
diff --git a/compiler/rustc_typeck/src/check/method/mod.rs b/compiler/rustc_typeck/src/check/method/mod.rs
index 2136d925423b9..bcb1aae71e5d7 100644
--- a/compiler/rustc_typeck/src/check/method/mod.rs
+++ b/compiler/rustc_typeck/src/check/method/mod.rs
@@ -29,7 +29,7 @@ use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 
 use self::probe::{IsSuggestion, ProbeScope};
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     suggest::provide(providers);
     probe::provide(providers);
 }
diff --git a/compiler/rustc_typeck/src/check/method/probe.rs b/compiler/rustc_typeck/src/check/method/probe.rs
index 9037ffe49a9a2..08f06c49def99 100644
--- a/compiler/rustc_typeck/src/check/method/probe.rs
+++ b/compiler/rustc_typeck/src/check/method/probe.rs
@@ -465,7 +465,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     providers.method_autoderef_steps = method_autoderef_steps;
 }
 
diff --git a/compiler/rustc_typeck/src/check/method/suggest.rs b/compiler/rustc_typeck/src/check/method/suggest.rs
index 7f4754448ba84..6fe93d5d8c232 100644
--- a/compiler/rustc_typeck/src/check/method/suggest.rs
+++ b/compiler/rustc_typeck/src/check/method/suggest.rs
@@ -1599,7 +1599,7 @@ fn compute_all_traits(tcx: TyCtxt<'_>, (): ()) -> &[DefId] {
     tcx.arena.alloc_from_iter(traits)
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
+pub const fn provide(providers: &mut ty::query::Providers) {
     providers.all_traits = compute_all_traits;
 }
 
diff --git a/compiler/rustc_typeck/src/check/mod.rs b/compiler/rustc_typeck/src/check/mod.rs
index ff7d291d3c909..493ecace2a5ec 100644
--- a/compiler/rustc_typeck/src/check/mod.rs
+++ b/compiler/rustc_typeck/src/check/mod.rs
@@ -236,7 +236,7 @@ impl<'tcx> EnclosingBreakables<'tcx> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     method::provide(providers);
     *providers = Providers {
         typeck_item_bodies,
diff --git a/compiler/rustc_typeck/src/coherence/mod.rs b/compiler/rustc_typeck/src/coherence/mod.rs
index 03a9fe01795f5..3b0bde640cce8 100644
--- a/compiler/rustc_typeck/src/coherence/mod.rs
+++ b/compiler/rustc_typeck/src/coherence/mod.rs
@@ -164,7 +164,7 @@ fn enforce_empty_impls_for_marker_traits(
     struct_span_err!(tcx.sess, span, E0715, "impls for marker traits cannot contain items").emit();
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     use self::builtin::coerce_unsized_info;
     use self::inherent_impls::{crate_inherent_impls, inherent_impls};
     use self::inherent_impls_overlap::crate_inherent_impls_overlap_check;
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index 506ca98b96026..08b09bb48af13 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -68,7 +68,7 @@ fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     );
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers {
         opt_const_param_of: type_of::opt_const_param_of,
         type_of: type_of::type_of,
diff --git a/compiler/rustc_typeck/src/impl_wf_check.rs b/compiler/rustc_typeck/src/impl_wf_check.rs
index 1240946860573..06a0a53782b3a 100644
--- a/compiler/rustc_typeck/src/impl_wf_check.rs
+++ b/compiler/rustc_typeck/src/impl_wf_check.rs
@@ -69,7 +69,7 @@ fn check_mod_impl_wf(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
         .visit_item_likes_in_module(module_def_id, &mut ImplWfCheck { tcx, min_specialization });
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_impl_wf, ..*providers };
 }
 
diff --git a/compiler/rustc_typeck/src/lib.rs b/compiler/rustc_typeck/src/lib.rs
index 92ef829747271..c4030531cf6ea 100644
--- a/compiler/rustc_typeck/src/lib.rs
+++ b/compiler/rustc_typeck/src/lib.rs
@@ -69,6 +69,8 @@ This API is completely unstable and subject to change.
 #![feature(never_type)]
 #![feature(slice_partition_dedup)]
 #![feature(control_flow_enum)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_mut_refs)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -455,7 +457,7 @@ fn check_for_entry_fn(tcx: TyCtxt<'_>) {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     collect::provide(providers);
     coherence::provide(providers);
     check::provide(providers);
diff --git a/compiler/rustc_typeck/src/outlives/mod.rs b/compiler/rustc_typeck/src/outlives/mod.rs
index d7eb31c2abef5..ee7b15ac8751d 100644
--- a/compiler/rustc_typeck/src/outlives/mod.rs
+++ b/compiler/rustc_typeck/src/outlives/mod.rs
@@ -13,7 +13,7 @@ mod implicit_infer;
 pub mod test;
 mod utils;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { inferred_outlives_of, inferred_outlives_crate, ..*providers };
 }
 
diff --git a/compiler/rustc_typeck/src/variance/mod.rs b/compiler/rustc_typeck/src/variance/mod.rs
index 66fb9eb86931b..1416c9f5117bf 100644
--- a/compiler/rustc_typeck/src/variance/mod.rs
+++ b/compiler/rustc_typeck/src/variance/mod.rs
@@ -26,7 +26,7 @@ pub mod test;
 /// Code for transforming variances.
 mod xform;
 
-pub fn provide(providers: &mut Providers) {
+pub const fn provide(providers: &mut Providers) {
     *providers = Providers { variances_of, crate_variances, ..*providers };
 }