RUN: not %swift_build_sdk_interfaces 2>&1 | %FileCheck -check-prefix NO-OUTPUT %s
NO-OUTPUT: argument -o is required

RUN: not env -u SDKROOT %swift_build_sdk_interfaces -o %t 2>&1 | %FileCheck -check-prefix NO-SDK %s
NO-SDK: SDKROOT must be set

RUN: not %swift_build_sdk_interfaces -o %t -sdk %S/nonexistent 2>&1 | %FileCheck -check-prefix BAD-SDK %s
BAD-SDK: invalid SDK: {{.+[/\\]nonexistent$}}