Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar

Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

src/base.rs

@@ -834,12 +834,6 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:
                         fx.bcx.ins().nop();
                     }
                 }
-                Rvalue::Len(place) => {
-                    let place = codegen_place(fx, place);
-                    let usize_layout = fx.layout_of(fx.tcx.types.usize);
-                    let len = codegen_array_len(fx, place);
-                    lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
-                }
                 Rvalue::ShallowInitBox(ref operand, content_ty) => {
                     let content_ty = fx.monomorphize(content_ty);
                     let box_layout = fx.layout_of(Ty::new_box(fx.tcx, content_ty));