Rollup merge of #124923 - RalfJung:offset-from-errors, r=compiler-errors

interpret/miri: better errors on failing offset_from

Fixes #3104

Author: matthiaskrgr

tests/fail/intrinsics/ptr_offset_from_different_ints.rs

@@ -0,0 +1,21 @@
+#![feature(strict_provenance)]
+use core::ptr;
+
+fn main() {
+    unsafe {
+        let base = ptr::without_provenance::<()>(10);
+        let unit = &*base;
+        let p1 = unit as *const ();
+
+        let base = ptr::without_provenance::<()>(11);
+        let unit = &*base;
+        let p2 = unit as *const ();
+
+        // Seems to work because they are same pointer
+        // even though it's dangling.
+        let _ = p1.byte_offset_from(p1);
+
+        // UB because different pointers.
+        let _ = p1.byte_offset_from(p2); //~ERROR: different pointers without provenance
+    }
+}

tests/fail/intrinsics/ptr_offset_from_different_ints.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: `ptr_offset_from` called on different pointers without provenance (i.e., without an associated allocation)
+  --> $DIR/ptr_offset_from_different_ints.rs:LL:CC
+   |
+LL |         let _ = p1.byte_offset_from(p2);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on different pointers without provenance (i.e., without an associated allocation)
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/ptr_offset_from_different_ints.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+