Auto merge of rust-lang#2726 - RalfJung:provenance-test, r=RalfJung

add provenance-related test

One of the cases in rust-lang/miri#2182 actually works as intended since rust-lang#104054 (or maybe even earlier); make sure we test that.

tests/pass/provenance.rs

@@ -10,6 +10,7 @@ fn main() {
     bytewise_ptr_methods();
     bytewise_custom_memcpy();
     bytewise_custom_memcpy_chunked();
+    int_load_strip_provenance();
 }
 
 /// Some basic smoke tests for provenance.
@@ -137,3 +138,9 @@ fn bytewise_custom_memcpy_chunked() {
         assert_eq!(*ptr, 42);
     }
 }
+
+fn int_load_strip_provenance() {
+    let ptrs = [&42];
+    let ints: [usize; 1] = unsafe { mem::transmute(ptrs) };
+    assert_eq!(ptrs[0] as *const _ as usize, ints[0]);
+}