Don't check suppressed protocols when the extended existential is metatype constrained

Author: Azoy

stdlib/public/runtime/ProtocolConformance.cpp

@@ -2229,6 +2229,14 @@ checkInvertibleRequirementsStructural(const Metadata *type,
   case MetadataKind::ExtendedExistential: {
     auto existential = cast<ExtendedExistentialTypeMetadata>(type);
     auto &shape = *existential->Shape;
+
+    // If this is an extended existential metatype, then just allow it. Metatypes
+    // are always copyable and escapable so there can't possibly be a
+    // suppression issue.
+    if (shape.Flags.isMetatypeConstrained()) {
+      return std::nullopt;
+    }
+
     llvm::ArrayRef<GenericRequirementDescriptor> reqs(
         shape.getReqSigRequirements(), shape.getNumReqSigRequirements());
     // Look for any suppressed protocol requirements. If the existential

test/Interpreter/extended_existential.swift

@@ -49,3 +49,21 @@ print(h)
 let i: Any = (any A & B & ~Copyable).self
 // CHECK: any A & B<Self: ~Swift.Copyable>
 print(i)
+
+@inline(never)
+func test() -> Bool {
+  return [].first == nil
+}
+
+// CHECK: true
+print(test())
+
+let j: [any (~Copyable & ~Escapable).Type] = []
+
+// CHECK: Array<any Any<Self: ~Swift.Copyable, Self: ~Swift.Escapable>.Type>
+print(type(of: j))
+
+let k: [(any ~Copyable & ~Escapable).Type] = []
+
+// CHECK: Array<(any Any<Self: ~Swift.Copyable, Self: ~Swift.Escapable>).Type>
+print(type(of: k))