`const_deallocate`: Don't deallocate memory allocated in an another const. Does nothing at runtime.

`const_allocate`:  Returns a null pointer at runtime.

3 files changed, 27 insertions, 4 deletions

diff --git a/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.rs b/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.rs
index 1a1d9a6d540..ac9e8b64b48 100644
--- a/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.rs
+++ b/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.rs
@@ -6,11 +6,10 @@ use std::intrinsics;
 const FOO: i32 = foo();
 const fn foo() -> i32 {
     unsafe {
-        let _ = intrinsics::const_allocate(4, 3) as * mut i32;
+        let _ = intrinsics::const_allocate(4, 3) as *mut i32;
         //~^ error: evaluation of constant value failed
     }
     1
-
 }
 
 fn main() {}
diff --git a/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.stderr b/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.stderr
index 74fb65ca1a6..2628a78455c 100644
--- a/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.stderr
+++ b/src/test/ui/consts/const-eval/heap/alloc_intrinsic_errors.stderr
@@ -4,7 +4,7 @@ error[E0080]: evaluation of constant value failed
 LL | const FOO: i32 = foo();
    |                  ----- inside `FOO` at $DIR/alloc_intrinsic_errors.rs:6:18
 ...
-LL |         let _ = intrinsics::const_allocate(4, 3) as * mut i32;
+LL |         let _ = intrinsics::const_allocate(4, 3) as *mut i32;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                 |
    |                 align has to be a power of 2, `3` is not a power of 2
diff --git a/src/test/ui/consts/const-eval/heap/dealloc_intrinsic.rs b/src/test/ui/consts/const-eval/heap/dealloc_intrinsic.rs
index b7c2b752644..aac90cd54cc 100644
--- a/src/test/ui/consts/const-eval/heap/dealloc_intrinsic.rs
+++ b/src/test/ui/consts/const-eval/heap/dealloc_intrinsic.rs
@@ -1,6 +1,7 @@
 // run-pass
 #![feature(core_intrinsics)]
 #![feature(const_heap)]
+#![feature(const_mut_refs)]
 
 use std::intrinsics;
 
@@ -9,4 +10,27 @@ const _X: () = unsafe {
     intrinsics::const_deallocate(ptr, 4, 4);
 };
 
-fn main() {}
+const Y: &u32 = unsafe {
+    let ptr = intrinsics::const_allocate(4, 4) as *mut u32;
+    *ptr = 42;
+    &*ptr
+};
+
+const Z: &u32 = &42;
+
+const _Z: () = unsafe {
+    let ptr1 = Y as *const _ as *mut u8;
+    intrinsics::const_deallocate(ptr1, 4, 4); // nop
+    intrinsics::const_deallocate(ptr1, 2, 4); // nop
+    intrinsics::const_deallocate(ptr1, 4, 2); // nop
+
+    let ptr2 = Z as *const _ as *mut u8;
+    intrinsics::const_deallocate(ptr2, 4, 4); // nop
+    intrinsics::const_deallocate(ptr2, 2, 4); // nop
+    intrinsics::const_deallocate(ptr2, 4, 2); // nop
+};
+
+fn main() {
+    assert_eq!(*Y, 42);
+    assert_eq!(*Z, 42);
+}