perf: Remove c_reverse from fullUnresolvedPath (sorbet#10110)

* perf: Remove `c_reverse` from `fullUnresolvedPath`

Minor optimization

* Preserve the printing order

Author: jez

ast/Trees.cc

@@ -349,6 +349,8 @@ optional<pair<core::SymbolRef, vector<core::NameRef>>> ConstantLit::fullUnresolv
     }
     ENFORCE(this->resolutionScopes() != nullptr && !this->resolutionScopes()->empty());
 
+    // This list is in reverse order, but that doesn't matter because all we ever use this for is
+    // for Type hashing, and don't care about the order for that.
     vector<core::NameRef> namesFailedToResolve;
     auto *nested = this;
     {
@@ -374,7 +376,6 @@ optional<pair<core::SymbolRef, vector<core::NameRef>>> ConstantLit::fullUnresolv
         }
         auto &orig = *nested->original();
         namesFailedToResolve.emplace_back(orig.cnst);
-        absl::c_reverse(namesFailedToResolve);
     }
     auto prefix = nested->resolutionScopes()->front();
     return make_pair(prefix, move(namesFailedToResolve));

core/types/printing.cc

@@ -36,7 +36,8 @@ string UnresolvedClassType::toStringWithTabs(const GlobalState &gs, int tabs) co
 
 string UnresolvedClassType::show(const GlobalState &gs, ShowOptions options) const {
     return fmt::format("{}::{} (unresolved)", this->scope.show(gs, options),
-                       fmt::map_join(this->names, "::", [&](const auto &el) -> string { return el.show(gs); }));
+                       fmt::map_join(this->names.rbegin(), this->names.rend(),
+                                     "::", [&](const auto &el) -> string { return el.show(gs); }));
 }
 
 string UnresolvedAppliedType::toStringWithTabs(const GlobalState &gs, int tabs) const {