syntax_data: {"ast_node_type":"variable","tokens":[{"end":90,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let fn_alloc_id = tcx.reserve_and_set_fn_alloc(instance, CTFE_ALLOC_SALT);
context_before:                 // Prepare the fn ptr we write into the vtable.
context_after:                 let fn_ptr = Pointer::from(fn_alloc_id);