[Gardening] Move the Documentation for getOpenedArchetypeSignature

Author: CodaFi

include/swift/AST/ASTContext.h

@@ -1300,6 +1300,15 @@ class ASTContext final {
   /// Retrieve a generic signature with a single type parameter conforming
   /// to the given protocol or composition type, like <T: type>.
   CanGenericSignature getOpenedArchetypeSignature(Type type);
+  /// to the given protocol or composition type, like <T: P>.
+  ///
+  /// The opened archetype may have a different set of conformances from the
+  /// corresponding existential. The opened archetype conformances are dictated
+  /// by the ABI for generic arguments, while the existential value conformances
+  /// are dictated by their layout (see \c Type::getExistentialLayout()). In
+  /// particular, the opened archetype signature does not have requirements for
+  /// conformances inherited from superclass constraints while existential
+  /// values do.
 
   GenericSignature getOverrideGenericSignature(const ValueDecl *base,
                                                const ValueDecl *derived);

lib/AST/ASTContext.cpp

@@ -5166,13 +5166,6 @@ CanGenericSignature ASTContext::getSingleGenericParameterSignature() const {
   return canonicalSig;
 }
 
-// Return the signature for an opened existential. The opened archetype may have
-// a different set of conformances from the corresponding existential. The
-// opened archetype conformances are dictated by the ABI for generic arguments,
-// while the existential value conformances are dictated by their layout (see
-// Type::getExistentialLayout()). In particular, the opened archetype signature
-// does not have requirements for conformances inherited from superclass
-// constraints while existential values do.
 CanGenericSignature ASTContext::getOpenedArchetypeSignature(Type type) {
   assert(type->isExistentialType());
   if (auto existential = type->getAs<ExistentialType>())