Auto merge of #99501 - lcnr:check-regions-infcx, r=oli-obk

move `considering_regions` to the infcx

it seems weird to prove some obligations which constrain inference vars while ignoring regions  in a context which considers regions. This is especially weird because even for a fulfillment context with ignored regions, we still added region outlives bounds when directly relating regions.

tbh our handling of regions is still very weird, but at least this is a step in the right direction imo.

r? rust-lang/types

compiler/rustc_typeck/src/check/inherited.rs

@@ -86,7 +86,10 @@ impl<'tcx> Inherited<'_, 'tcx> {
         let hir_owner = tcx.hir().local_def_id_to_hir_id(def_id).owner;
 
         InheritedBuilder {
-            infcx: tcx.infer_ctxt().with_fresh_in_progress_typeck_results(hir_owner),
+            infcx: tcx
+                .infer_ctxt()
+                .ignoring_regions()
+                .with_fresh_in_progress_typeck_results(hir_owner),
             def_id,
         }
     }
@@ -113,7 +116,7 @@ impl<'a, 'tcx> Inherited<'a, 'tcx> {
                 maybe_typeck_results: infcx.in_progress_typeck_results,
             },
             infcx,
-            fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new_ignoring_regions(tcx)),
+            fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
             locals: RefCell::new(Default::default()),
             deferred_sized_obligations: RefCell::new(Vec::new()),
             deferred_call_resolutions: RefCell::new(Default::default()),

compiler/rustc_typeck/src/check/mod.rs

@@ -87,10 +87,10 @@ mod op;
 mod pat;
 mod place_op;
 mod region;
-mod regionck;
+pub mod regionck;
 pub mod rvalue_scopes;
 mod upvar;
-mod wfcheck;
+pub mod wfcheck;
 pub mod writeback;
 
 use check::{check_abi, check_fn, check_mod_item_types};

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -1913,7 +1913,7 @@ impl<'a, 'tcx> WfCheckingCtxt<'a, 'tcx> {
     }
 }
 
-pub(super) fn impl_implied_bounds<'tcx>(
+pub fn impl_implied_bounds<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     impl_def_id: LocalDefId,

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -116,8 +116,8 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
                 // why this field does not implement Copy. This is useful because sometimes
                 // it is not immediately clear why Copy is not implemented for a field, since
                 // all we point at is the field itself.
-                tcx.infer_ctxt().enter(|infcx| {
-                    let mut fulfill_cx = traits::FulfillmentContext::new_ignoring_regions();
+                tcx.infer_ctxt().ignoring_regions().enter(|infcx| {
+                    let mut fulfill_cx = traits::FulfillmentContext::new();
                     fulfill_cx.register_bound(
                         &infcx,
                         param_env,

compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs

@@ -65,6 +65,8 @@
 //! cause use after frees with purely safe code in the same way as specializing
 //! on traits with methods can.
 
+use crate::check::regionck::OutlivesEnvironmentExt;
+use crate::check::wfcheck::impl_implied_bounds;
 use crate::constrained_generic_params as cgp;
 use crate::errors::SubstsOnOverriddenImpl;
 
@@ -148,8 +150,15 @@ fn get_impl_substs<'tcx>(
     let impl2_substs =
         translate_substs(infcx, param_env, impl1_def_id.to_def_id(), impl1_substs, impl2_node);
 
-    // Conservatively use an empty `ParamEnv`.
-    let outlives_env = OutlivesEnvironment::new(ty::ParamEnv::empty());
+    let mut outlives_env = OutlivesEnvironment::new(param_env);
+    let implied_bounds =
+        impl_implied_bounds(infcx.tcx, param_env, impl1_def_id, tcx.def_span(impl1_def_id));
+    outlives_env.add_implied_bounds(
+        infcx,
+        implied_bounds,
+        tcx.hir().local_def_id_to_hir_id(impl1_def_id),
+    );
+    infcx.process_registered_region_obligations(outlives_env.region_bound_pairs(), param_env);
     infcx.resolve_regions_and_report_errors(impl1_def_id, &outlives_env);
     let Ok(impl2_substs) = infcx.fully_resolve(impl2_substs) else {
         let span = tcx.def_span(impl1_def_id);