[Sema] Remove checks preventing metatype keypaths in Sema.

Author: amritpan

include/swift/Sema/CSFix.h

@@ -2007,8 +2007,6 @@ class TreatKeyPathSubscriptIndexAsHashable final : public ConstraintFix {
 
 class AllowInvalidRefInKeyPath final : public ConstraintFix {
   enum RefKind {
-    // Allow a reference to a static member as a key path component.
-    StaticMember,
     // Allow a reference to a declaration with mutating getter as
     // a key path component.
     MutatingGetter,
@@ -2032,8 +2030,6 @@ class AllowInvalidRefInKeyPath final : public ConstraintFix {
 public:
   std::string getName() const override {
     switch (Kind) {
-    case RefKind::StaticMember:
-      return "allow reference to a static member as a key path component";
     case RefKind::MutatingGetter:
       return "allow reference to a member with mutating getter as a key "
              "path component";

lib/Sema/CSApply.cpp

@@ -5286,9 +5286,6 @@ namespace {
         auto varDecl = cast<VarDecl>(property);
         // Key paths don't work with mutating-get properties.
         assert(!varDecl->isGetterMutating());
-        // Key paths don't currently support static members.
-        // There is a fix which diagnoses such situation already.
-        assert(!varDecl->isStatic());
 
         // Compute the concrete reference to the member.
         auto ref = resolveConcreteDeclRef(property, locator);

lib/Sema/CSFix.cpp

@@ -1205,11 +1205,6 @@ TreatKeyPathSubscriptIndexAsHashable::create(ConstraintSystem &cs, Type type,
 bool AllowInvalidRefInKeyPath::diagnose(const Solution &solution,
                                         bool asNote) const {
   switch (Kind) {
-  case RefKind::StaticMember: {
-    InvalidStaticMemberRefInKeyPath failure(solution, Member, getLocator());
-    return failure.diagnose(asNote);
-  }
-
   case RefKind::EnumCase: {
     InvalidEnumCaseRefInKeyPath failure(solution, Member, getLocator());
     return failure.diagnose(asNote);
@@ -1273,11 +1268,6 @@ AllowInvalidRefInKeyPath::forRef(ConstraintSystem &cs, ValueDecl *member,
     return AllowInvalidRefInKeyPath::create(cs, RefKind::Initializer,
                                             member, locator);
 
-  // Referencing static members in key path is not currently allowed.
-  if (member->isStatic())
-    return AllowInvalidRefInKeyPath::create(cs, RefKind::StaticMember, member,
-                                            locator);
-
   if (auto *storage = dyn_cast<AbstractStorageDecl>(member)) {
     // Referencing members with mutating getters in key path is not
     // currently allowed.