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[Runtime] Always fail to find a conditional conformance at runtime.

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Proper evaluation of conditional conformances at runtime (e.g., as part of
dynamic casting) is too large to tackle in the Swift 4.1 timeframe. For now,
record that a conformance is conditional in the protocol conformance record,
and always return "does not conform" to such types.

Fixes rdar://problem/35761301.
This commit is contained in:
Doug Gregor
2017-12-04 16:51:52 -08:00
parent 59ee97f4af
commit 4f8edeb913
8 changed files with 77 additions and 10 deletions
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11
stdlib/public/runtime/ProtocolConformance.cpp
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@@ -84,6 +84,10 @@ template<> void ProtocolConformanceRecord::dump() const {
printf("witness table accessor %s\n",
symbolName((const void *)(uintptr_t)getWitnessTableAccessor()));
break;
case ProtocolConformanceReferenceKind::ConditionalWitnessTableAccessor:
printf("conditional witness table accessor %s\n",
symbolName((const void *)(uintptr_t)getWitnessTableAccessor()));
break;
}
}
#endif
@@ -136,8 +140,12 @@ const {
return getStaticWitnessTable();
case ProtocolConformanceReferenceKind::WitnessTableAccessor:
// FIXME: this needs information about conditional conformances.
return getWitnessTableAccessor()(type, nullptr, 0);
case ProtocolConformanceReferenceKind::ConditionalWitnessTableAccessor:
// FIXME: this needs to query the conditional requirements to form the
// array of witness tables to pass along to the accessor.
return nullptr;
}
swift_runtime_unreachable(
@@ -558,6 +566,7 @@ swift::swift_conformsToProtocol(const Metadata * const type,
break;
case ProtocolConformanceReferenceKind::WitnessTableAccessor:
case ProtocolConformanceReferenceKind::ConditionalWitnessTableAccessor:
// If the record provides a dependent witness table accessor,
// cache the result for the instantiated type metadata.
C.cacheSuccess(type, P, record.getWitnessTable(type));