syntax_data: {"ast_node_type":"other","tokens":[{"end":93,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! Optional keys are in TargetOptions, but Target derefs to it, for no practical difference.
context_before: //! Some fields are required in every target spec, and they should be embedded in Target directly.
context_after: //! Most notable is the "data-layout" field which specifies Rust's notion of sizes and alignments