From bcc44b8e025978ae14ff11d484aacbb85aa8eaed Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sat, 2 May 2020 14:39:12 -0700
Subject: [PATCH 1/2] Test associated const default qualifs cross-crate

This also tests for the ICE in #71734
---
 .../const_in_pattern/auxiliary/consts.rs       |  5 +++++
 .../const_in_pattern/cross-crate-fail.rs       | 12 ++++++++++++
 .../const_in_pattern/cross-crate-fail.stderr   | 18 +++++++++++++++---
 .../const_in_pattern/cross-crate-pass.rs       |  9 +++++++++
 4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/test/ui/consts/const_in_pattern/auxiliary/consts.rs b/src/test/ui/consts/const_in_pattern/auxiliary/consts.rs
index 303c2f12bbce9..b438bcd9fb5eb 100644
--- a/src/test/ui/consts/const_in_pattern/auxiliary/consts.rs
+++ b/src/test/ui/consts/const_in_pattern/auxiliary/consts.rs
@@ -9,3 +9,8 @@ impl PartialEq for CustomEq {
 
 pub const NONE: Option<CustomEq> = None;
 pub const SOME: Option<CustomEq> = Some(CustomEq);
+
+pub trait AssocConst {
+    const NONE: Option<CustomEq> = None;
+    const SOME: Option<CustomEq> = Some(CustomEq);
+}
diff --git a/src/test/ui/consts/const_in_pattern/cross-crate-fail.rs b/src/test/ui/consts/const_in_pattern/cross-crate-fail.rs
index c9e6050fdc508..05c53e5edccc5 100644
--- a/src/test/ui/consts/const_in_pattern/cross-crate-fail.rs
+++ b/src/test/ui/consts/const_in_pattern/cross-crate-fail.rs
@@ -4,7 +4,11 @@
 
 extern crate consts;
 
+struct Defaulted;
+impl consts::AssocConst for Defaulted {}
+
 fn main() {
+    let _ = Defaulted;
     match None {
         consts::SOME => panic!(),
         //~^ must be annotated with `#[derive(PartialEq, Eq)]`
@@ -12,4 +16,12 @@ fn main() {
 
         _ => {}
     }
+
+    match None {
+        <Defaulted as consts::AssocConst>::SOME  => panic!(),
+        //~^ must be annotated with `#[derive(PartialEq, Eq)]`
+        //~| must be annotated with `#[derive(PartialEq, Eq)]`
+
+        _ => {}
+    }
 }
diff --git a/src/test/ui/consts/const_in_pattern/cross-crate-fail.stderr b/src/test/ui/consts/const_in_pattern/cross-crate-fail.stderr
index c97298f66e677..5d147e32f5a86 100644
--- a/src/test/ui/consts/const_in_pattern/cross-crate-fail.stderr
+++ b/src/test/ui/consts/const_in_pattern/cross-crate-fail.stderr
@@ -1,14 +1,26 @@
 error: to use a constant of type `consts::CustomEq` in a pattern, `consts::CustomEq` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/cross-crate-fail.rs:9:9
+  --> $DIR/cross-crate-fail.rs:13:9
    |
 LL |         consts::SOME => panic!(),
    |         ^^^^^^^^^^^^
 
 error: to use a constant of type `consts::CustomEq` in a pattern, `consts::CustomEq` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/cross-crate-fail.rs:9:9
+  --> $DIR/cross-crate-fail.rs:21:9
+   |
+LL |         <Defaulted as consts::AssocConst>::SOME  => panic!(),
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: to use a constant of type `consts::CustomEq` in a pattern, `consts::CustomEq` must be annotated with `#[derive(PartialEq, Eq)]`
+  --> $DIR/cross-crate-fail.rs:13:9
    |
 LL |         consts::SOME => panic!(),
    |         ^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: to use a constant of type `consts::CustomEq` in a pattern, `consts::CustomEq` must be annotated with `#[derive(PartialEq, Eq)]`
+  --> $DIR/cross-crate-fail.rs:21:9
+   |
+LL |         <Defaulted as consts::AssocConst>::SOME  => panic!(),
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/consts/const_in_pattern/cross-crate-pass.rs b/src/test/ui/consts/const_in_pattern/cross-crate-pass.rs
index ccf655c11cf8a..1d8ecf8ae6640 100644
--- a/src/test/ui/consts/const_in_pattern/cross-crate-pass.rs
+++ b/src/test/ui/consts/const_in_pattern/cross-crate-pass.rs
@@ -6,9 +6,18 @@
 extern crate consts;
 use consts::CustomEq;
 
+struct Defaulted;
+impl consts::AssocConst for Defaulted {}
+
 fn main() {
+    let _ = Defaulted;
     match Some(CustomEq) {
         consts::NONE => panic!(),
         _ => {}
     }
+
+    match Some(CustomEq) {
+        <Defaulted as consts::AssocConst>::NONE  => panic!(),
+        _ => {}
+    }
 }

From 14a2c8d042e1da811d96b843922e569f2cd5e283 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sat, 2 May 2020 14:17:04 -0700
Subject: [PATCH 2/2] Decode qualifs from defaulted trait associated consts

---
 src/librustc_metadata/rmeta/decoder.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/librustc_metadata/rmeta/decoder.rs b/src/librustc_metadata/rmeta/decoder.rs
index 6a4b35ed3d7fa..04f17230717d9 100644
--- a/src/librustc_metadata/rmeta/decoder.rs
+++ b/src/librustc_metadata/rmeta/decoder.rs
@@ -1123,11 +1123,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         match self.kind(id) {
             EntryKind::Const(qualif, _)
             | EntryKind::AssocConst(
-                AssocContainer::ImplDefault | AssocContainer::ImplFinal,
+                AssocContainer::ImplDefault
+                | AssocContainer::ImplFinal
+                | AssocContainer::TraitWithDefault,
                 qualif,
                 _,
             ) => qualif,
-            _ => bug!(),
+            _ => bug!("mir_const_qualif: unexpected kind"),
         }
     }