embed-metadata
This option instructs rustc to include the full metadata in rlib and dylib crate types. The default value is yes (enabled). If disabled (no), only stub metadata will be stored in these files, to reduce their size on disk. When using -Zembed-metadata=no, you will probably want to use --emit=metadata to produce the full metadata into a separate .rmeta file.
Note that this flag has been stabilized as -Cembed-metadata. The unstable variant of the flag is provided purely for making the migration easier; it will be removed in the future.