Remove hook calling via TyCtxtAt.

All hooks receive a `TyCtxtAt` argument.

Currently hooks can be called through `TyCtxtAt` or `TyCtxt`. In the
latter case, a `TyCtxtAt` is constructed with a dummy span and passed to
the hook.

However, in practice hooks are never called through `TyCtxtAt`, and
always receive a dummy span. (I confirmed this via code inspection, and
double-checked it by temporarily making the `TyCtxtAt` code path panic
and running all the tests.)

This commit removes all the `TyCtxtAt` machinery for hooks. All hooks
now receive `TyCtxt` instead of `TyCtxtAt`. There are two existing hooks
that use `TyCtxtAt::span`: `const_caller_location_provider` and
`try_destructure_mir_constant_for_user_output`. For both hooks the span
is always a dummy span, probably unintentionally. This dummy span use is
now explicit. If a non-dummy span is needed for these two hooks it would
be easy to add it as an extra argument because hooks are less
constrained than queries.

Author: nnethercote

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -1,7 +1,7 @@
 // Not in interpret to make sure we do not use private implementation details
 
 use rustc_abi::VariantIdx;
-use rustc_middle::query::{Key, TyCtxtAt};
+use rustc_middle::query::Key;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
@@ -35,16 +35,17 @@ pub(crate) type ValTreeCreationResult<'tcx> = Result<ty::ValTree<'tcx>, ValTreeC
 
 #[instrument(skip(tcx), level = "debug")]
 pub(crate) fn try_destructure_mir_constant_for_user_output<'tcx>(
-    tcx: TyCtxtAt<'tcx>,
+    tcx: TyCtxt<'tcx>,
     val: mir::ConstValue<'tcx>,
     ty: Ty<'tcx>,
 ) -> Option<mir::DestructuredConstant<'tcx>> {
     let typing_env = ty::TypingEnv::fully_monomorphized();
-    let (ecx, op) = mk_eval_cx_for_const_val(tcx, typing_env, val, ty)?;
+    // FIXME: use a proper span here?
+    let (ecx, op) = mk_eval_cx_for_const_val(tcx.at(rustc_span::DUMMY_SP), typing_env, val, ty)?;
 
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match ty.kind() {
-        ty::Array(_, len) => (len.try_to_target_usize(tcx.tcx)? as usize, None, op),
+        ty::Array(_, len) => (len.try_to_target_usize(tcx)? as usize, None, op),
         ty::Adt(def, _) if def.variants().is_empty() => {
             return None;
         }

compiler/rustc_const_eval/src/util/caller_location.rs

@@ -1,7 +1,6 @@
 use rustc_hir::LangItem;
-use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::LayoutOf;
-use rustc_middle::ty::{self};
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{bug, mir};
 use rustc_span::Symbol;
 use tracing::trace;
@@ -48,15 +47,15 @@ fn alloc_caller_location<'tcx>(
 }
 
 pub(crate) fn const_caller_location_provider(
-    tcx: TyCtxtAt<'_>,
+    tcx: TyCtxt<'_>,
     file: Symbol,
     line: u32,
     col: u32,
 ) -> mir::ConstValue<'_> {
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx_to_read_const_val(
-        tcx.tcx,
-        tcx.span,
+        tcx,
+        rustc_span::DUMMY_SP, // FIXME: use a proper span here?
         ty::TypingEnv::fully_monomorphized(),
         CanAccessMutGlobal::No,
     );

compiler/rustc_incremental/src/lib.rs

@@ -24,7 +24,7 @@ use rustc_middle::util::Providers;
 #[allow(missing_docs)]
 pub fn provide(providers: &mut Providers) {
     providers.hooks.save_dep_graph =
-        |tcx| tcx.sess.time("serialize_dep_graph", || persist::save_dep_graph(tcx.tcx));
+        |tcx| tcx.sess.time("serialize_dep_graph", || persist::save_dep_graph(tcx));
 }
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }

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

@@ -689,7 +689,7 @@ fn provide_cstore_hooks(providers: &mut Providers) {
     providers.hooks.def_path_hash_to_def_id_extern = |tcx, hash, stable_crate_id| {
         // If this is a DefPathHash from an upstream crate, let the CrateStore map
         // it to a DefId.
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         let cnum = *tcx
             .untracked()
             .stable_crate_ids
@@ -702,11 +702,11 @@ fn provide_cstore_hooks(providers: &mut Providers) {
     };
 
     providers.hooks.expn_hash_to_expn_id = |tcx, cnum, index_guess, hash| {
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         cstore.get_crate_data(cnum).expn_hash_to_expn_id(tcx.sess, index_guess, hash)
     };
     providers.hooks.import_source_files = |tcx, cnum| {
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         let cdata = cstore.get_crate_data(cnum);
         for file_index in 0..cdata.root.source_map.size() {
             cdata.imported_source_file(file_index as u32, tcx.sess);

compiler/rustc_middle/src/hooks/mod.rs

@@ -6,11 +6,9 @@
 use rustc_hir::def_id::{DefId, DefPathHash};
 use rustc_session::StableCrateId;
 use rustc_span::def_id::{CrateNum, LocalDefId};
-use rustc_span::{DUMMY_SP, ExpnHash, ExpnId};
-use tracing::instrument;
+use rustc_span::{ExpnHash, ExpnId};
 
 use crate::mir;
-use crate::query::TyCtxtAt;
 use crate::ty::{Ty, TyCtxt};
 
 macro_rules! declare_hooks {
@@ -22,26 +20,14 @@ macro_rules! declare_hooks {
             #[inline(always)]
             pub fn $name(self, $($arg: $K,)*) -> $V
             {
-                self.at(DUMMY_SP).$name($($arg,)*)
-            }
-            )*
-        }
-
-        impl<'tcx> TyCtxtAt<'tcx> {
-            $(
-            $(#[$attr])*
-            #[inline(always)]
-            #[instrument(level = "debug", skip(self), ret)]
-            pub fn $name(self, $($arg: $K,)*) -> $V
-            {
-                (self.tcx.hooks.$name)(self, $($arg,)*)
+                (self.hooks.$name)(self, $($arg,)*)
             }
             )*
         }
 
         pub struct Providers {
             $(pub $name: for<'tcx> fn(
-                TyCtxtAt<'tcx>,
+                TyCtxt<'tcx>,
                 $($arg: $K,)*
             ) -> $V,)*
         }

compiler/rustc_mir_transform/src/coverage/query.rs

@@ -6,7 +6,6 @@ use rustc_middle::mir::coverage::{
     FunctionCoverageInfo, MappingKind, Op,
 };
 use rustc_middle::mir::{Body, Statement, StatementKind};
-use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::util::Providers;
 use rustc_span::def_id::LocalDefId;
@@ -15,8 +14,7 @@ use tracing::trace;
 
 /// Registers query/hook implementations related to coverage.
 pub(crate) fn provide(providers: &mut Providers) {
-    providers.hooks.is_eligible_for_coverage =
-        |TyCtxtAt { tcx, .. }, def_id| is_eligible_for_coverage(tcx, def_id);
+    providers.hooks.is_eligible_for_coverage = is_eligible_for_coverage;
     providers.queries.coverage_attr_on = coverage_attr_on;
     providers.queries.coverage_ids_info = coverage_ids_info;
 }

compiler/rustc_monomorphize/src/collector.rs

@@ -953,7 +953,7 @@ fn visit_instance_use<'tcx>(
 
 /// 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.
-fn should_codegen_locally<'tcx>(tcx: TyCtxtAt<'tcx>, instance: Instance<'tcx>) -> bool {
+fn should_codegen_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) -> bool {
     let Some(def_id) = instance.def.def_id_if_not_guaranteed_local_codegen() else {
         return true;
     };
@@ -976,7 +976,7 @@ fn should_codegen_locally<'tcx>(tcx: TyCtxtAt<'tcx>, instance: Instance<'tcx>) -
         return true;
     }
 
-    if tcx.is_reachable_non_generic(def_id) || instance.upstream_monomorphization(*tcx).is_some() {
+    if tcx.is_reachable_non_generic(def_id) || instance.upstream_monomorphization(tcx).is_some() {
         // We can link to the item in question, no instance needed in this crate.
         return false;
     }

compiler/rustc_query_impl/src/lib.rs

@@ -224,7 +224,6 @@ pub fn query_system<'a>(
 rustc_middle::rustc_query_append! { define_queries! }
 
 pub fn provide(providers: &mut rustc_middle::util::Providers) {
-    providers.hooks.alloc_self_profile_query_strings =
-        |tcx| alloc_self_profile_query_strings(tcx.tcx);
-    providers.hooks.query_key_hash_verify_all = |tcx| query_key_hash_verify_all(tcx.tcx);
+    providers.hooks.alloc_self_profile_query_strings = alloc_self_profile_query_strings;
+    providers.hooks.query_key_hash_verify_all = query_key_hash_verify_all;
 }