Rollup merge of #106170 - compiler-errors:autoderef-to-analysis, r=lcnr

Move autoderef to `rustc_hir_analysis`

Not sure if this is a change we actually want, but autoderef really is only (functionally) used by `rustc_hir_analysis` and `rustc_hir_typeck`, so it probably should live there.

Instead, implement a separate autoderef helper in `TypeErrCtxt` for the one use-case that  goes against the ordering of the crate graph..

16 files changed, 70 insertions, 46 deletions

diff --git a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
index 26cdf8a58f3..41f458f6c17 100644
--- a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
@@ -120,3 +120,7 @@ hir_analysis_self_in_impl_self =
 
 hir_analysis_linkage_type =
     invalid type for variable with `#[linkage]` attribute
+
+hir_analysis_auto_deref_reached_recursion_limit = reached the recursion limit while auto-dereferencing `{$ty}`
+    .label = deref recursion limit reached
+    .help = consider increasing the recursion limit by adding a `#![recursion_limit = "{$suggested_limit}"]` attribute to your crate (`{$crate_name}`)
diff --git a/compiler/rustc_error_messages/locales/en-US/trait_selection.ftl b/compiler/rustc_error_messages/locales/en-US/trait_selection.ftl
index 004e0ab1896..14eb4a5502d 100644
--- a/compiler/rustc_error_messages/locales/en-US/trait_selection.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/trait_selection.ftl
@@ -2,10 +2,6 @@ trait_selection_dump_vtable_entries = vtable entries for `{$trait_ref}`: {$entri
 
 trait_selection_unable_to_construct_constant_value = unable to construct a constant value for the unevaluated constant {$unevaluated}
 
-trait_selection_auto_deref_reached_recursion_limit = reached the recursion limit while auto-dereferencing `{$ty}`
-    .label = deref recursion limit reached
-    .help = consider increasing the recursion limit by adding a `#![recursion_limit = "{$suggested_limit}"]` attribute to your crate (`{$crate_name}`)
-
 trait_selection_empty_on_clause_in_rustc_on_unimplemented = empty `on`-clause in `#[rustc_on_unimplemented]`
     .label = empty on-clause here
 
diff --git a/compiler/rustc_trait_selection/src/autoderef.rs b/compiler/rustc_hir_analysis/src/autoderef.rs
index e988c77a064..730560cc686 100644
--- a/compiler/rustc_trait_selection/src/autoderef.rs
+++ b/compiler/rustc_hir_analysis/src/autoderef.rs
@@ -178,6 +178,10 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         self.state.obligations
     }
 
+    pub fn current_obligations(&self) -> Vec<traits::PredicateObligation<'tcx>> {
+        self.state.obligations.clone()
+    }
+
     pub fn steps(&self) -> &[(Ty<'tcx>, AutoderefKind)] {
         &self.state.steps
     }
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index e9baab59453..d1f4dbc8d84 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -1,4 +1,6 @@
+use crate::autoderef::Autoderef;
 use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};
+
 use hir::def::DefKind;
 use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
@@ -22,7 +24,6 @@ use rustc_session::parse::feature_err;
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::autoderef::Autoderef;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index d383fcacb3a..04f5f3f6276 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -300,3 +300,15 @@ pub(crate) struct LinkageType {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[help]
+#[diag(hir_analysis_auto_deref_reached_recursion_limit, code = "E0055")]
+pub struct AutoDerefReachedRecursionLimit<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub ty: Ty<'a>,
+    pub suggested_limit: rustc_session::Limit,
+    pub crate_name: Symbol,
+}
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 2058832d5fd..65c1d7f373a 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -84,6 +84,7 @@ extern crate rustc_middle;
 pub mod check;
 
 pub mod astconv;
+pub mod autoderef;
 mod bounds;
 mod check_unused;
 mod coherence;
diff --git a/compiler/rustc_hir_typeck/src/autoderef.rs b/compiler/rustc_hir_typeck/src/autoderef.rs
index 41b52a4c4a9..7873257c4e3 100644
--- a/compiler/rustc_hir_typeck/src/autoderef.rs
+++ b/compiler/rustc_hir_typeck/src/autoderef.rs
@@ -2,11 +2,11 @@
 use super::method::MethodCallee;
 use super::{FnCtxt, PlaceOp};
 
+use rustc_hir_analysis::autoderef::{Autoderef, AutoderefKind};
 use rustc_infer::infer::InferOk;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
 use rustc_middle::ty::{self, Ty};
 use rustc_span::Span;
-use rustc_trait_selection::autoderef::{Autoderef, AutoderefKind};
 
 use std::iter;
 
diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index 3b664363d23..8d417290407 100644
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -8,6 +8,7 @@ use rustc_errors::{struct_span_err, Applicability, Diagnostic, ErrorGuaranteed,
 use rustc_hir as hir;
 use rustc_hir::def::{self, CtorKind, Namespace, Res};
 use rustc_hir::def_id::DefId;
+use rustc_hir_analysis::autoderef::Autoderef;
 use rustc_infer::{
     infer,
     traits::{self, Obligation},
@@ -25,7 +26,6 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
 use rustc_target::spec::abi;
-use rustc_trait_selection::autoderef::Autoderef;
 use rustc_trait_selection::infer::InferCtxtExt as _;
 use rustc_trait_selection::traits::error_reporting::DefIdOrName;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index 6347b9a69a0..27db4d27b60 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Const, Ty, TyCtxt, TypeVisitable};
 use rustc_session::Session;
 use rustc_span::symbol::Ident;
-use rustc_span::{self, Span};
+use rustc_span::{self, Span, DUMMY_SP};
 use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode, ObligationCtxt};
 
 use std::cell::{Cell, RefCell};
@@ -175,6 +175,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     fn_sig
                 })
             }),
+            autoderef_steps: Box::new(|ty| {
+                let mut autoderef = self.autoderef(DUMMY_SP, ty).silence_errors();
+                let mut steps = vec![];
+                while let Some((ty, _)) = autoderef.next() {
+                    steps.push((ty, autoderef.current_obligations()));
+                }
+                steps
+            }),
         }
     }
 
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 5d8383170f0..ba9c0c8d15e 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -9,6 +9,7 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
+use rustc_hir_analysis::autoderef::{self, Autoderef};
 use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
@@ -29,7 +30,6 @@ use rustc_span::lev_distance::{
 };
 use rustc_span::symbol::sym;
 use rustc_span::{symbol::Ident, Span, Symbol, DUMMY_SP};
-use rustc_trait_selection::autoderef::{self, Autoderef};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::query::method_autoderef::MethodAutoderefBadTy;
 use rustc_trait_selection::traits::query::method_autoderef::{
diff --git a/compiler/rustc_hir_typeck/src/place_op.rs b/compiler/rustc_hir_typeck/src/place_op.rs
index a0f048fc09b..ae0df5aa8f1 100644
--- a/compiler/rustc_hir_typeck/src/place_op.rs
+++ b/compiler/rustc_hir_typeck/src/place_op.rs
@@ -3,6 +3,7 @@ use crate::{has_expected_num_generic_args, FnCtxt, PlaceOp};
 use rustc_ast as ast;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
+use rustc_hir_analysis::autoderef::Autoderef;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::InferOk;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref, PointerCast};
@@ -10,7 +11,6 @@ use rustc_middle::ty::adjustment::{AllowTwoPhase, AutoBorrow, AutoBorrowMutabili
 use rustc_middle::ty::{self, Ty};
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
-use rustc_trait_selection::autoderef::Autoderef;
 use std::slice;
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 66db1a2f928..0223979263d 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -55,6 +55,7 @@ use crate::infer::ExpectedFound;
 use crate::traits::error_reporting::report_object_safety_error;
 use crate::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
+    PredicateObligation,
 };
 
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -91,8 +92,12 @@ pub mod nice_region_error;
 pub struct TypeErrCtxt<'a, 'tcx> {
     pub infcx: &'a InferCtxt<'tcx>,
     pub typeck_results: Option<std::cell::Ref<'a, ty::TypeckResults<'tcx>>>,
-    pub normalize_fn_sig: Box<dyn Fn(ty::PolyFnSig<'tcx>) -> ty::PolyFnSig<'tcx> + 'a>,
     pub fallback_has_occurred: bool,
+
+    pub normalize_fn_sig: Box<dyn Fn(ty::PolyFnSig<'tcx>) -> ty::PolyFnSig<'tcx> + 'a>,
+
+    pub autoderef_steps:
+        Box<dyn Fn(Ty<'tcx>) -> Vec<(Ty<'tcx>, Vec<PredicateObligation<'tcx>>)> + 'a>,
 }
 
 impl TypeErrCtxt<'_, '_> {
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 6bef3f000a5..8825b5e12c3 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -688,6 +688,10 @@ impl<'tcx> InferCtxt<'tcx> {
             typeck_results: None,
             fallback_has_occurred: false,
             normalize_fn_sig: Box::new(|fn_sig| fn_sig),
+            autoderef_steps: Box::new(|ty| {
+                debug_assert!(false, "shouldn't be using autoderef_steps outside of typeck");
+                vec![(ty, vec![])]
+            }),
         }
     }
 
diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index 19f404cb5b7..4405537c645 100644
--- a/compiler/rustc_trait_selection/src/errors.rs
+++ b/compiler/rustc_trait_selection/src/errors.rs
@@ -1,7 +1,6 @@
 use rustc_errors::{fluent, ErrorGuaranteed, Handler, IntoDiagnostic};
 use rustc_macros::Diagnostic;
 use rustc_middle::ty::{self, PolyTraitRef, Ty};
-use rustc_session::Limit;
 use rustc_span::{Span, Symbol};
 
 #[derive(Diagnostic)]
@@ -22,18 +21,6 @@ pub struct UnableToConstructConstantValue<'a> {
 }
 
 #[derive(Diagnostic)]
-#[help]
-#[diag(trait_selection_auto_deref_reached_recursion_limit, code = "E0055")]
-pub struct AutoDerefReachedRecursionLimit<'a> {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    pub ty: Ty<'a>,
-    pub suggested_limit: Limit,
-    pub crate_name: Symbol,
-}
-
-#[derive(Diagnostic)]
 #[diag(trait_selection_empty_on_clause_in_rustc_on_unimplemented, code = "E0232")]
 pub struct EmptyOnClauseInOnUnimplemented {
     #[primary_span]
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index a30d1df4ede..081ac966c69 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -35,7 +35,6 @@ extern crate rustc_middle;
 #[macro_use]
 extern crate smallvec;
 
-pub mod autoderef;
 pub mod errors;
 pub mod infer;
 pub mod solve;
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 53769742c47..48694bac3bc 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -5,7 +5,6 @@ use super::{
     PredicateObligation,
 };
 
-use crate::autoderef::Autoderef;
 use crate::infer::InferCtxt;
 use crate::traits::{NormalizeExt, ObligationCtxt};
 
@@ -750,26 +749,30 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             }
 
             if let ty::Ref(region, base_ty, mutbl) = *real_ty.skip_binder().kind() {
-                let mut autoderef = Autoderef::new(
-                    self,
-                    obligation.param_env,
-                    obligation.cause.body_id,
-                    span,
-                    base_ty,
-                );
-                if let Some(steps) = autoderef.find_map(|(ty, steps)| {
-                    // Re-add the `&`
-                    let ty = self.tcx.mk_ref(region, TypeAndMut { ty, mutbl });
-
-                    // Remapping bound vars here
-                    let real_trait_pred_and_ty =
-                        real_trait_pred.map_bound(|inner_trait_pred| (inner_trait_pred, ty));
-                    let obligation = self.mk_trait_obligation_with_new_self_ty(
-                        obligation.param_env,
-                        real_trait_pred_and_ty,
-                    );
-                    Some(steps).filter(|_| self.predicate_may_hold(&obligation))
-                }) {
+                let autoderef = (self.autoderef_steps)(base_ty);
+                if let Some(steps) =
+                    autoderef.into_iter().enumerate().find_map(|(steps, (ty, obligations))| {
+                        // Re-add the `&`
+                        let ty = self.tcx.mk_ref(region, TypeAndMut { ty, mutbl });
+
+                        // Remapping bound vars here
+                        let real_trait_pred_and_ty =
+                            real_trait_pred.map_bound(|inner_trait_pred| (inner_trait_pred, ty));
+                        let obligation = self.mk_trait_obligation_with_new_self_ty(
+                            obligation.param_env,
+                            real_trait_pred_and_ty,
+                        );
+                        if obligations
+                            .iter()
+                            .chain([&obligation])
+                            .all(|obligation| self.predicate_may_hold(obligation))
+                        {
+                            Some(steps)
+                        } else {
+                            None
+                        }
+                    })
+                {
                     if steps > 0 {
                         // Don't care about `&mut` because `DerefMut` is used less
                         // often and user will not expect autoderef happens.