pub fn try_source_file(file: &str) -> Option<eprog>Expand description
Port of try_source_file(char *file) from Src/parse.c:3795.
Returns an Eprog (the wordcode dump body) if <file>.zwc exists
and is newer than <file>, else None. The dump entry searched is
the file’s basename (tail), matching how zcompile names
source-file entries.