Nate Chandler 07ba7a6f3c [runtime] Exported multi payload enum witnesses. ...

When witness tables for enums are instantiated at runtime via

    swift::swift_initEnumMetadataMultiPayload

the witnesses

    getEnumTagSinglePayload
    storeEnumTagSinglePayload

are filled with swift_getMultiPayloadEnumTagSinglePayload (previously
getMultiPayloadEnumTagSinglePayload) and
swift_storeMultiPayloadEnumTagSinglePayload (previously
storeMultiPayloadEnumTagSinglePayload).  Concretely, that occurs when
instantiating the value witness table for a generic enum which has more
than one case with a payload, like Result<T>.  To enable the compiler to
do the same work, those functions need to be visible to it.

Here, those functions are made visible to the compiler.  Doing so
requires changing the way they are declared and adding them to
RuntimeFunctions.def which in turn requires the definition of some
functions to describe the availability of those functions.

2021-06-25 21:03:56 -07:00

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