From a4a5e5b4ae2431c09b228bfb3e2930a1c38b9e45 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sun, 30 Jan 2022 17:14:54 +0100
Subject: Querify unused trait check.

---
 compiler/rustc_hir_analysis/src/check_unused.rs | 9 +++++++--
 compiler/rustc_hir_analysis/src/lib.rs          | 3 ++-
 compiler/rustc_middle/src/query/mod.rs          | 4 ++++
 3 files changed, 13 insertions(+), 3 deletions(-)

(limited to 'compiler')

diff --git a/compiler/rustc_hir_analysis/src/check_unused.rs b/compiler/rustc_hir_analysis/src/check_unused.rs
index 5318e637fc7..d10bc5b34ea 100644
--- a/compiler/rustc_hir_analysis/src/check_unused.rs
+++ b/compiler/rustc_hir_analysis/src/check_unused.rs
@@ -1,11 +1,16 @@
 use rustc_data_structures::unord::{ExtendUnord, UnordSet};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
+use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint;
 
-pub fn check_crate(tcx: TyCtxt<'_>) {
-    let mut used_trait_imports: UnordSet<LocalDefId> = Default::default();
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers { check_unused_traits, ..*providers };
+}
+
+fn check_unused_traits(tcx: TyCtxt<'_>, (): ()) {
+    let mut used_trait_imports = UnordSet::<LocalDefId>::default();
 
     // FIXME: Use `tcx.hir().par_body_owners()` when we implement creating `DefId`s
     // for anon constants during their parents' typeck.
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index d7e62457f36..4f95174f869 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -177,6 +177,7 @@ pub fn provide(providers: &mut Providers) {
     collect::provide(providers);
     coherence::provide(providers);
     check::provide(providers);
+    check_unused::provide(providers);
     variance::provide(providers);
     outlives::provide(providers);
     impl_wf_check::provide(providers);
@@ -247,7 +248,7 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
         }
     });
 
-    check_unused::check_crate(tcx);
+    tcx.ensure().check_unused_traits(());
 
     if let Some(reported) = tcx.sess.has_errors() { Err(reported) } else { Ok(()) }
 }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 45fa82ba68a..8f5f92f80d8 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -898,6 +898,10 @@ rustc_queries! {
         desc { |tcx| "linting {}", describe_as_module(key, tcx) }
     }
 
+    query check_unused_traits(_: ()) -> () {
+        desc { "checking unused trait imports in crate" }
+    }
+
     /// Checks the attributes in the module.
     query check_mod_attrs(key: LocalDefId) -> () {
         desc { |tcx| "checking attributes in {}", describe_as_module(key, tcx) }
-- 
cgit 1.4.1-3-g733a5