Auto merge of rust-lang#89550 - lcnr:coherence-specialization, r=nikomatsakis

do not emit overlap errors for impls failing the orphan check

this should finally allow us to merge rust-lang#86986, see rust-lang#86986 (comment) for more details.

r? `@nikomatsakis` cc `@eddyb`

Author: bors

compiler/rustc_middle/src/query/mod.rs

@@ -822,6 +822,14 @@ rustc_queries! {
         desc { "check for overlap between inherent impls defined in this crate" }
     }
 
+    /// Checks whether all impls in the crate pass the overlap check, returning
+    /// which impls fail it. If all impls are correct, the returned slice is empty.
+    query orphan_check_crate(_: ()) -> &'tcx [LocalDefId] {
+        desc {
+            "checking whether the immpl in the this crate follow the orphan rules",
+        }
+    }
+
     /// Check whether the function has any recursion that could cause the inliner to trigger
     /// a cycle. Returns the call stack causing the cycle. The call stack does not contain the
     /// current function, just all intermediate functions.
@@ -1056,11 +1064,6 @@ rustc_queries! {
     }
 
     /// Return all `impl` blocks in the current crate.
-    ///
-    /// To allow caching this between crates, you must pass in [`LOCAL_CRATE`] as the crate number.
-    /// Passing in any other crate will cause an ICE.
-    ///
-    /// [`LOCAL_CRATE`]: rustc_hir::def_id::LOCAL_CRATE
     query all_local_trait_impls(_: ()) -> &'tcx BTreeMap<DefId, Vec<LocalDefId>> {
         desc { "local trait impls" }
     }

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -291,6 +291,11 @@ pub(super) fn specialization_graph_provider(
     sg
 }
 
+// This function is only used when
+// encountering errors and inlining
+// it negatively impacts perf.
+#[cold]
+#[inline(never)]
 fn report_overlap_conflict(
     tcx: TyCtxt<'_>,
     overlap: OverlapError,
@@ -443,8 +448,12 @@ fn report_conflicting_impls(
     match used_to_be_allowed {
         None => {
             sg.has_errored = true;
-            let err = struct_span_err!(tcx.sess, impl_span, E0119, "");
-            decorate(LintDiagnosticBuilder::new(err));
+            if overlap.with_impl.is_local() || !tcx.orphan_check_crate(()).contains(&impl_def_id) {
+                let err = struct_span_err!(tcx.sess, impl_span, E0119, "");
+                decorate(LintDiagnosticBuilder::new(err));
+            } else {
+                tcx.sess.delay_span_bug(impl_span, "impl should have failed the orphan check");
+            }
         }
         Some(kind) => {
             let lint = match kind {

compiler/rustc_typeck/src/coherence/mod.rs

@@ -168,13 +168,15 @@ pub 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;
+    use self::orphan::orphan_check_crate;
 
     *providers = Providers {
         coherent_trait,
         crate_inherent_impls,
         inherent_impls,
         crate_inherent_impls_overlap_check,
         coerce_unsized_info,
+        orphan_check_crate,
         ..*providers
     };
 }
@@ -195,13 +197,13 @@ fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) {
 }
 
 pub fn check_coherence(tcx: TyCtxt<'_>) {
+    tcx.sess.time("unsafety_checking", || unsafety::check(tcx));
+    tcx.ensure().orphan_check_crate(());
+
     for &trait_def_id in tcx.all_local_trait_impls(()).keys() {
         tcx.ensure().coherent_trait(trait_def_id);
     }
 
-    tcx.sess.time("unsafety_checking", || unsafety::check(tcx));
-    tcx.sess.time("orphan_checking", || orphan::check(tcx));
-
     // these queries are executed for side-effects (error reporting):
     tcx.ensure().crate_inherent_impls(());
     tcx.ensure().crate_inherent_impls_overlap_check(());