syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // t-opsem before removing this check.
context_before:                     // determining their size. Therefore, we cannot allow `extern` types here. Consult
context_after:                     panic!("unsized arguments must not be `extern` types");