Validate nested static items

tests/ui/statics/mutable_memory_validation.rs

@@ -0,0 +1,21 @@
+//issue: rust-lang/rust#122548
+
+// Strip out raw byte dumps to make comparison platform-independent:
+//@ normalize-stderr-test "(the raw bytes of the constant) \(size: [0-9]*, align: [0-9]*\)" -> "$1 (size: $$SIZE, align: $$ALIGN)"
+//@ normalize-stderr-test "([0-9a-f][0-9a-f] |╾─*A(LLOC)?[0-9]+(\+[a-z0-9]+)?(<imm>)?─*╼ )+ *│.*" -> "HEX_DUMP"
+
+#![feature(const_mut_refs)]
+#![feature(const_refs_to_static)]
+
+use std::cell::UnsafeCell;
+
+struct Meh {
+    x: &'static UnsafeCell<i32>,
+}
+
+const MUH: Meh = Meh { x: unsafe { &mut *(&READONLY as *const _ as *mut _) } };
+//~^ ERROR: it is undefined behavior to use this value
+
+static READONLY: i32 = 0;
+
+pub fn main() {}