syntax_data: {"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // a constant and write that value back into `Operand`s. This could happen, but is
context_before:             // We should never encounter `Const::Val` unless MIR opts (like const prop) evaluate
context_after:             // unlikely. Also: all users of `simd_shuffle` are on unstable and already need to take