pub fn collect_string_interp_refs(src: &str, refs: &mut HashSet<String>)Expand description
Extract every leaf {name} placeholder mentioned inside
string-literal contexts in src into refs.
Used by the synthesiser to discover names the body
references via {name} interpolation that don’t appear as
bare identifiers in the Polydat source. The detection is
quote-aware: leading non-identifier chars (', ") skip
the placeholder, matching the binding compiler’s
string_lit_has_real_placeholder disambiguation.