Rollup merge of #137298 - compiler-errors:mir-wf, r=lcnr

Check signature WF when lowering MIR body

Alternative to #137233.

https://github.com/rust-lang/rust/pull/137233#issuecomment-2667879143

Fixes https://github.com/rust-lang/rust/issues/137186

We do this check in `mir_drops_elaborated_and_const_checked` and not during `mir_promoted` because that may result in borrowck cycles if WF requires looking into an opaque hidden type. This causes some TAIT tests to fail unnecessarily.

r? lcnr

try-job: test-various

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -3126,8 +3126,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     Applicability::MachineApplicable,
                 );
             }
-            ObligationCauseCode::ConstSized => {
-                err.note("constant expressions must have a statically known size");
+            ObligationCauseCode::SizedConstOrStatic => {
+                err.note("statics and constants must have a statically known size");
             }
             ObligationCauseCode::InlineAsmSized => {
                 err.note("all inline asm arguments must have a statically known size");