const: make ptr.is_null() stop execution on ambiguity

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/ui/consts/const-ptr-is-null.rs b/tests/ui/consts/const-ptr-is-null.rs
new file mode 100644
index 00000000000..82c293c0ad6
--- /dev/null
+++ b/tests/ui/consts/const-ptr-is-null.rs
@@ -0,0 +1,20 @@
+#![feature(const_ptr_is_null)]
+use std::ptr;
+
+const IS_NULL: () = {
+    assert!(ptr::null::<u8>().is_null());
+};
+const IS_NOT_NULL: () = {
+    assert!(!ptr::null::<u8>().wrapping_add(1).is_null());
+};
+
+const MAYBE_NULL: () = {
+    let x = 15;
+    let ptr = &x as *const i32;
+    // This one is still unambiguous...
+    assert!(!ptr.is_null());
+    // but once we shift outside the allocation, we might become null.
+    assert!(!ptr.wrapping_sub(512).is_null()); //~inside `MAYBE_NULL`
+};
+
+fn main() {}