Auto merge of #115524 - RalfJung:misalign, r=wesleywiser

const-eval: make misalignment a hard error

It's been a future-incompat error (showing up in cargo's reports) since https://github.com/rust-lang/rust/pull/104616, Rust 1.68, released in March.  That should be long enough.

The question for the lang team is simply -- should we move ahead with this, making const-eval alignment failures a hard error? (It turns out some of them accidentally already were hard errors since #104616. But not all so this is still a breaking change. Crater found no regression.)

compiler/rustc_lint/src/lib.rs

@@ -506,6 +506,11 @@ fn register_builtins(store: &mut LintStore) {
         "replaced with another group of lints, see RFC \
          <https://rust-lang.github.io/rfcs/2145-type-privacy.html> for more information",
     );
+    store.register_removed(
+        "invalid_alignment",
+        "converted into hard error, see PR #104616 \
+         <https://github.com/rust-lang/rust/pull/104616> for more information",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {