rustup

rust-version

@@ -1 +1 @@
-8824d131619e58a38bde8bcf56401629b91a204a
+1517f5de01c445b5124b30f02257b02b4c5ef3b2

src/diagnostics.rs

@@ -291,8 +291,8 @@ pub fn report_error<'tcx, 'mir>(
     match e.kind() {
         UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
             eprintln!(
-                "Uninitialized read occurred at {alloc_id:?}{range:?}, in this allocation:",
-                range = alloc_range(access.uninit_offset, access.uninit_size),
+                "Uninitialized memory occurred at {alloc_id:?}{range:?}, in this allocation:",
+                range = access.uninit,
             );
             eprintln!("{:?}", ecx.dump_alloc(*alloc_id));
         }

tests/fail/uninit_buffer.rs

@@ -1,4 +1,4 @@
-// error-pattern: 12 bytes are uninitialized
+// error-pattern: memory is uninitialized at [0x4..0x10]
 
 use std::alloc::{alloc, dealloc, Layout};
 use std::slice::from_raw_parts;

tests/fail/uninit_buffer.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: reading 16 bytes of memory starting at ALLOC, but 12 bytes are uninitialized starting at ALLOC+0x4, and this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x10], but memory is uninitialized at [0x4..0x10], and this operation requires initialized memory
   --> RUSTLIB/core/src/slice/cmp.rs:LL:CC
    |
 LL |         let mut order = unsafe { memcmp(left.as_ptr(), right.as_ptr(), len) as isize };
-   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading 16 bytes of memory starting at ALLOC, but 12 bytes are uninitialized starting at ALLOC+0x4, and this operation requires initialized memory
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading memory at ALLOC[0x0..0x10], but memory is uninitialized at [0x4..0x10], and this operation requires initialized memory
    |
    = 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
@@ -17,7 +17,7 @@ LL |         drop(slice1.cmp(slice2));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-Uninitialized read occurred at ALLOC[0x4..0x10], in this allocation:
+Uninitialized memory occurred at ALLOC[0x4..0x10], in this allocation:
 ALLOC (Rust heap, size: 32, align: 8) {
     0x00 │ 41 42 43 44 __ __ __ __ __ __ __ __ __ __ __ __ │ ABCD░░░░░░░░░░░░
     0x10 │ 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ .░░░░░░░░░░░░░░░