From 18318a9d848950680c12c17183f175c7c511c2ce Mon Sep 17 00:00:00 2001
From: =?utf8?q?D=C3=A1niel=20Buga?= <bugadani@gmail.com>
Date: Fri, 9 Oct 2020 16:56:09 +0200
Subject: [PATCH] Reimplement for_each_relevant_impl on top of find_map...

---
 compiler/rustc_middle/src/ty/trait_def.rs | 47 ++++++++---------------
 1 file changed, 17 insertions(+), 30 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index 5599216c316..86476dffc03 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -123,10 +123,26 @@ pub fn for_each_relevant_impl<F: FnMut(DefId)>(
         self_ty: Ty<'tcx>,
         mut f: F,
     ) {
+        let _: Option<()> = self.find_map_relevant_impl(def_id, self_ty, |did| {
+            f(did);
+            None
+        });
+    }
+
+    /// Applies function to every impl that could possibly match the self type `self_ty` and returns
+    /// the first non-none value.
+    pub fn find_map_relevant_impl<T, F: FnMut(DefId) -> Option<T>>(
+        self,
+        def_id: DefId,
+        self_ty: Ty<'tcx>,
+        mut f: F,
+    ) -> Option<T> {
         let impls = self.trait_impls_of(def_id);
 
         for &impl_def_id in impls.blanket_impls.iter() {
-            f(impl_def_id);
+            if let result @ Some(_) = f(impl_def_id) {
+                return result;
+            }
         }
 
         // simplify_type(.., false) basically replaces type parameters and
@@ -154,35 +170,6 @@ pub fn for_each_relevant_impl<F: FnMut(DefId)>(
         // blanket and non-blanket impls, and compare them separately.
         //
         // I think we'll cross that bridge when we get to it.
-        if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) {
-            if let Some(impls) = impls.non_blanket_impls.get(&simp) {
-                for &impl_def_id in impls {
-                    f(impl_def_id);
-                }
-            }
-        } else {
-            for &impl_def_id in impls.non_blanket_impls.values().flatten() {
-                f(impl_def_id);
-            }
-        }
-    }
-
-    /// Applies function to every impl that could possibly match the self type `self_ty` and returns
-    /// the first non-none value.
-    pub fn find_map_relevant_impl<T, F: Fn(DefId) -> Option<T>>(
-        self,
-        def_id: DefId,
-        self_ty: Ty<'tcx>,
-        f: F,
-    ) -> Option<T> {
-        let impls = self.trait_impls_of(def_id);
-
-        for &impl_def_id in impls.blanket_impls.iter() {
-            if let result @ Some(_) = f(impl_def_id) {
-                return result;
-            }
-        }
-
         if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) {
             if let Some(impls) = impls.non_blanket_impls.get(&simp) {
                 for &impl_def_id in impls {
-- 
2.44.0