From a73e7d0a4df305e8b8237163e5ac7755cf488af8 Mon Sep 17 00:00:00 2001
From: Avi Dessauer <avi.the.coder@gmail.com>
Date: Sun, 12 Jul 2020 20:56:37 -0400
Subject: [PATCH] Test unstable Alloc param on Box

---
 .../auxiliary/unstable_generic_param.rs       | 36 ++++++++++++++++++-
 .../generics-default-stability.rs             |  6 ++++
 .../generics-default-stability.stderr         | 10 +++++-
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/src/test/ui/stability-attribute/auxiliary/unstable_generic_param.rs b/src/test/ui/stability-attribute/auxiliary/unstable_generic_param.rs
index 82eed9a38f9..b26908c25e3 100644
--- a/src/test/ui/stability-attribute/auxiliary/unstable_generic_param.rs
+++ b/src/test/ui/stability-attribute/auxiliary/unstable_generic_param.rs
@@ -1,6 +1,5 @@
 #![crate_type = "lib"]
 #![feature(staged_api)]
-
 #![stable(feature = "stable_test_feature", since = "1.0.0")]
 
 #[stable(feature = "stable_test_feature", since = "1.0.0")]
@@ -75,3 +74,38 @@ pub const STRUCT4: Struct4 = Struct4 { field: 1 };
 
 #[stable(feature = "stable_test_feature", since = "1.0.0")]
 pub const STRUCT5: Struct5 = Struct5 { field: 1 };
+
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+pub trait Alloc {}
+
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+pub struct System {}
+
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+impl Alloc for System {}
+
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+pub struct Box1<T, #[unstable(feature = "box_alloc_param", issue = "none")] A: Alloc = System> {
+    ptr: *mut T,
+    alloc: A,
+}
+
+impl<T> Box1<T, System> {
+    #[stable(feature = "stable_test_feature", since = "1.0.0")]
+    pub fn new(mut t: T) -> Self {
+        unsafe { Self { ptr: &mut t, alloc: System {} } }
+    }
+}
+
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+pub struct Box2<T, A: Alloc = System> {
+    ptr: *mut T,
+    alloc: A,
+}
+
+impl<T> Box2<T, System> {
+    #[stable(feature = "stable_test_feature", since = "1.0.0")]
+    pub fn new(mut t: T) -> Self {
+        Self { ptr: &mut t, alloc: System {} }
+    }
+}
diff --git a/src/test/ui/stability-attribute/generics-default-stability.rs b/src/test/ui/stability-attribute/generics-default-stability.rs
index 26f7692209f..d412aceb3a2 100644
--- a/src/test/ui/stability-attribute/generics-default-stability.rs
+++ b/src/test/ui/stability-attribute/generics-default-stability.rs
@@ -109,4 +109,10 @@ fn main() {
 
     let _: Struct6<isize> = Struct6 { field: 1 }; // ok
     let _: Struct6<isize> = Struct6 { field: 0 }; // ok
+
+    let _: Box1<isize, System> = Box1::new(1); //~ ERROR use of unstable library feature 'box_alloc_param'
+    let _: Box1<isize> = Box1::new(1); // ok
+
+    let _: Box2<isize, System> = Box2::new(1); // ok
+    let _: Box2<isize> = Box2::new(1); // ok
 }
diff --git a/src/test/ui/stability-attribute/generics-default-stability.stderr b/src/test/ui/stability-attribute/generics-default-stability.stderr
index d9e195c21d6..37a809f8bca 100644
--- a/src/test/ui/stability-attribute/generics-default-stability.stderr
+++ b/src/test/ui/stability-attribute/generics-default-stability.stderr
@@ -168,6 +168,14 @@ LL |     let _: Struct5<isize> = Struct5 { field: 0 };
    |
    = help: add `#![feature(unstable_default)]` to the crate attributes to enable
 
+error[E0658]: use of unstable library feature 'box_alloc_param'
+  --> $DIR/generics-default-stability.rs:113:24
+   |
+LL |     let _: Box1<isize, System> = Box1::new(1);
+   |                        ^^^^^^
+   |
+   = help: add `#![feature(box_alloc_param)]` to the crate attributes to enable
+
 warning: use of deprecated item 'unstable_generic_param::Struct4::field': test
   --> $DIR/generics-default-stability.rs:84:39
    |
@@ -192,6 +200,6 @@ warning: use of deprecated item 'unstable_generic_param::Struct5::field': test
 LL |     let _: Struct5<isize> = Struct5 { field: 0 };
    |                                       ^^^^^^^^
 
-error: aborting due to 12 previous errors; 16 warnings emitted
+error: aborting due to 13 previous errors; 16 warnings emitted
 
 For more information about this error, try `rustc --explain E0658`.