Decouple trait impls of different traits wrt incremental

Author: oli-obk

compiler/rustc_hir_analysis/src/coherence/mod.rs

@@ -153,9 +153,12 @@ pub(crate) fn provide(providers: &mut Providers) {
 }
 
 fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) -> Result<(), ErrorGuaranteed> {
+    let impls = tcx.local_trait_impls(def_id);
     // If there are no impls for the trait, then "all impls" are trivially coherent and we won't check anything
     // anyway. Thus we bail out even before the specialization graph, avoiding the dep_graph edge.
-    let Some(impls) = tcx.all_local_trait_impls(()).get(&def_id) else { return Ok(()) };
+    if impls.is_empty() {
+        return Ok(());
+    }
     // Trigger building the specialization graph for the trait. This will detect and report any
     // overlap errors.
     let mut res = tcx.ensure_ok().specialization_graph_of(def_id);

compiler/rustc_middle/src/hir/map.rs

@@ -368,7 +368,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn hir_trait_impls(self, trait_did: DefId) -> &'tcx [LocalDefId] {
-        self.all_local_trait_impls(()).get(&trait_did).map_or(&[], |xs| &xs[..])
+        self.local_trait_impls(trait_did)
     }
 
     /// Gets the attributes on the crate. This is preferable to

compiler/rustc_middle/src/hir/mod.rs

@@ -233,6 +233,8 @@ pub fn provide(providers: &mut Providers) {
         }
     };
     providers.all_local_trait_impls = |tcx, ()| &tcx.resolutions(()).trait_impls;
+    providers.local_trait_impls =
+        |tcx, trait_id| tcx.resolutions(()).trait_impls.get(&trait_id).map_or(&[], |xs| &xs[..]);
     providers.expn_that_defined =
         |tcx, id| tcx.resolutions(()).expn_that_defined.get(&id).copied().unwrap_or(ExpnId::root());
     providers.in_scope_traits_map = |tcx, id| {

compiler/rustc_middle/src/query/mod.rs

@@ -1484,6 +1484,11 @@ rustc_queries! {
         desc { "finding local trait impls" }
     }
 
+    /// Return all `impl` blocks of the given trait in the current crate.
+    query local_trait_impls(trait_id: DefId) -> &'tcx [LocalDefId] {
+        desc { "finding local trait impls of `{}`", tcx.def_path_str(trait_id) }
+    }
+
     /// Given a trait `trait_id`, return all known `impl` blocks.
     query trait_impls_of(trait_id: DefId) -> &'tcx ty::trait_def::TraitImpls {
         arena_cache

src/tools/clippy/clippy_lints/src/derive.rs

@@ -324,11 +324,9 @@ fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &h
     // there's a Copy impl for any instance of the adt.
     if !is_copy(cx, ty) {
         if ty_subs.non_erasable_generics().next().is_some() {
-            let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(&copy_id).is_some_and(|impls| {
-                impls.iter().any(|&id| {
-                    matches!(cx.tcx.type_of(id).instantiate_identity().kind(), ty::Adt(adt, _)
+            let has_copy_impl = cx.tcx.local_trait_impls(copy_id).iter().any(|&id| {
+                matches!(cx.tcx.type_of(id).instantiate_identity().kind(), ty::Adt(adt, _)
                                         if ty_adt.did() == adt.did())
-                })
             });
             if !has_copy_impl {
                 return;