syntax_data: {"ast_node_type":"other","tokens":[{"end":6,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     //
context_before:     //   show up in the `wasm-import-name` custom attribute in LLVM IR.
context_after:     // * `#[rustc_std_internal_symbol]` mangles the symbol name in a special way