lld/test/wasm/Inputs/use-feature-foo.yaml

--- !WASM
FileHeader:
  Version:         0x00000001
Sections:
  - Type:            CUSTOM
    Name:            linking
    Version:         2
  - Type:            CUSTOM
    Name:            target_features
    Features:
      - Prefix:        USED
        Name:          "foo"
...