From fcbbbfc479a2aab86f88c783e5e66e7cfee39e84 Mon Sep 17 00:00:00 2001
From: Randalphwa <38287198+Randalphwa@users.noreply.github.com>
Date: Mon, 30 Mar 2026 22:02:30 -0700
Subject: [PATCH 1/4] Change bits/ include path

Use "bits/xxx.h" not "frozen/bits/xxx.h" -- that way the host can set their include path to "include/frozen" rather than "include".
---
 include/frozen/algorithm.h        |  6 +++---
 include/frozen/bits/algorithms.h  |  2 +-
 include/frozen/bits/basic_types.h |  4 ++--
 include/frozen/bits/pmh.h         |  4 ++--
 include/frozen/map.h              | 10 +++++-----
 include/frozen/random.h           |  4 ++--
 include/frozen/set.h              |  5 ++---
 include/frozen/string.h           | 10 +++++++++-
 include/frozen/unordered_map.h    | 12 +++++-------
 include/frozen/unordered_set.h    | 10 +++++-----
 10 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/include/frozen/algorithm.h b/include/frozen/algorithm.h
index a538f7c..4238367 100644
--- a/include/frozen/algorithm.h
+++ b/include/frozen/algorithm.h
@@ -32,9 +32,9 @@
     #error "frozen/algorithm.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/basic_types.h"
-#include "frozen/bits/version.h"
-#include "frozen/string.h"
+#include "bits/basic_types.h"
+#include "bits/version.h"
+#include "string.h"
 
 namespace frozen
 {
diff --git a/include/frozen/bits/algorithms.h b/include/frozen/bits/algorithms.h
index 310c31d..fc792f6 100644
--- a/include/frozen/bits/algorithms.h
+++ b/include/frozen/bits/algorithms.h
@@ -22,7 +22,7 @@
 
 #pragma once
 
-#include "frozen/bits/basic_types.h"
+#include "basic_types.h"
 
 #include <limits>
 #include <tuple>
diff --git a/include/frozen/bits/basic_types.h b/include/frozen/bits/basic_types.h
index 817908f..336229e 100644
--- a/include/frozen/bits/basic_types.h
+++ b/include/frozen/bits/basic_types.h
@@ -22,8 +22,8 @@
 
 #pragma once
 
-#include "frozen/bits/constexpr_assert.h"
-#include "frozen/bits/exceptions.h"
+#include "constexpr_assert.h"
+#include "exceptions.h"
 
 #include <array>
 #include <concepts>
diff --git a/include/frozen/bits/pmh.h b/include/frozen/bits/pmh.h
index 7591886..16f6d26 100644
--- a/include/frozen/bits/pmh.h
+++ b/include/frozen/bits/pmh.h
@@ -23,8 +23,8 @@
 // inspired from http://stevehanov.ca/blog/index.php?id=119
 #pragma once
 
-#include "frozen/bits/algorithms.h"
-#include "frozen/bits/basic_types.h"
+#include "algorithms.h"
+#include "basic_types.h"
 
 #include <cstddef>
 #include <cstdint>
diff --git a/include/frozen/map.h b/include/frozen/map.h
index 733b51a..0dc8b81 100644
--- a/include/frozen/map.h
+++ b/include/frozen/map.h
@@ -31,11 +31,11 @@
     #error "frozen/map.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/algorithms.h"
-#include "frozen/bits/basic_types.h"
-#include "frozen/bits/exceptions.h"
-#include "frozen/bits/mpl.h"
-#include "frozen/bits/version.h"
+#include "bits/algorithms.h"
+#include "bits/basic_types.h"
+#include "bits/exceptions.h"
+#include "bits/mpl.h"
+#include "bits/version.h"
 
 #include <functional>
 #include <iterator>
diff --git a/include/frozen/random.h b/include/frozen/random.h
index 1d41232..c6db3bd 100644
--- a/include/frozen/random.h
+++ b/include/frozen/random.h
@@ -31,8 +31,8 @@
     #error "frozen/random.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/algorithms.h"
-#include "frozen/bits/version.h"
+#include "bits/algorithms.h"
+#include "bits/version.h"
 
 #include <concepts>
 #include <cstdint>
diff --git a/include/frozen/set.h b/include/frozen/set.h
index 2ee4195..45552d5 100644
--- a/include/frozen/set.h
+++ b/include/frozen/set.h
@@ -31,9 +31,8 @@
     #error "frozen/set.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/algorithms.h"
-#include "frozen/bits/basic_types.h"
-#include "frozen/bits/version.h"
+#include "bits/algorithms.h"
+#include "bits/basic_types.h"
 
 #include <functional>
 #include <iterator>
diff --git a/include/frozen/string.h b/include/frozen/string.h
index 71ad52d..dc4cf90 100644
--- a/include/frozen/string.h
+++ b/include/frozen/string.h
@@ -1,6 +1,14 @@
 #pragma once
 
-#include "frozen/bits/version.h"
+// Require C++23 or later
+#if defined(_MSVC_LANG)
+    #if _MSVC_LANG < 202302L
+        #error \
+            "frozen/unordered_map.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
+    #endif
+#elif __cplusplus < 202302L
+    #error "frozen/unordered_map.h requires C++23 or later. Compile with -std=c++23 or later."
+#endif
 
 #include <cstddef>
 #include <string_view>
diff --git a/include/frozen/unordered_map.h b/include/frozen/unordered_map.h
index cacea20..56d888d 100644
--- a/include/frozen/unordered_map.h
+++ b/include/frozen/unordered_map.h
@@ -32,15 +32,13 @@
     #error "frozen/unordered_map.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/basic_types.h"
-#include "frozen/bits/elsa.h"
-#include "frozen/bits/exceptions.h"
-#include "frozen/bits/pmh.h"
-#include "frozen/bits/version.h"
-#include "frozen/random.h"
+#include "bits/basic_types.h"
+#include "bits/elsa.h"
+#include "bits/exceptions.h"
+#include "bits/pmh.h"
+#include "random.h"
 
 #include <functional>
-#include <tuple>
 #include <utility>
 
 namespace frozen
diff --git a/include/frozen/unordered_set.h b/include/frozen/unordered_set.h
index 4d19112..2385518 100644
--- a/include/frozen/unordered_set.h
+++ b/include/frozen/unordered_set.h
@@ -32,11 +32,11 @@
     #error "frozen/unordered_set.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
-#include "frozen/bits/basic_types.h"
-#include "frozen/bits/elsa.h"
-#include "frozen/bits/pmh.h"
-#include "frozen/bits/version.h"
-#include "frozen/random.h"
+#include "bits/basic_types.h"
+#include "bits/elsa.h"
+#include "bits/pmh.h"
+#include "bits/version.h"
+#include "random.h"
 
 #include <functional>
 #include <utility>

From a65469e2a133fc4fbfa21bbebf515b94c1ccb687 Mon Sep 17 00:00:00 2001
From: Randalphwa <38287198+Randalphwa@users.noreply.github.com>
Date: Fri, 3 Apr 2026 08:32:55 -0700
Subject: [PATCH 2/4] Remove unused header files

---
 include/frozen/algorithm.h | 2 --
 include/frozen/map.h       | 1 -
 include/frozen/random.h    | 1 -
 3 files changed, 4 deletions(-)

diff --git a/include/frozen/algorithm.h b/include/frozen/algorithm.h
index 4238367..6b92bac 100644
--- a/include/frozen/algorithm.h
+++ b/include/frozen/algorithm.h
@@ -33,8 +33,6 @@
 #endif
 
 #include "bits/basic_types.h"
-#include "bits/version.h"
-#include "string.h"
 
 namespace frozen
 {
diff --git a/include/frozen/map.h b/include/frozen/map.h
index 0dc8b81..73260f6 100644
--- a/include/frozen/map.h
+++ b/include/frozen/map.h
@@ -35,7 +35,6 @@
 #include "bits/basic_types.h"
 #include "bits/exceptions.h"
 #include "bits/mpl.h"
-#include "bits/version.h"
 
 #include <functional>
 #include <iterator>
diff --git a/include/frozen/random.h b/include/frozen/random.h
index c6db3bd..88e2df5 100644
--- a/include/frozen/random.h
+++ b/include/frozen/random.h
@@ -32,7 +32,6 @@
 #endif
 
 #include "bits/algorithms.h"
-#include "bits/version.h"
 
 #include <concepts>
 #include <cstdint>

From 26a89038845cff8324a8846c6b8e427b02cd32ec Mon Sep 17 00:00:00 2001
From: Randalphwa <38287198+Randalphwa@users.noreply.github.com>
Date: Fri, 3 Apr 2026 08:33:41 -0700
Subject: [PATCH 3/4] Refactor/cleanup

---
 include/frozen/set.h           | 20 +++++----
 include/frozen/unordered_set.h | 77 ++++++++++++++++++----------------
 2 files changed, 53 insertions(+), 44 deletions(-)

diff --git a/include/frozen/set.h b/include/frozen/set.h
index 45552d5..a79b300 100644
--- a/include/frozen/set.h
+++ b/include/frozen/set.h
@@ -100,9 +100,10 @@ namespace frozen
         {
             const_iterator where = lower_bound(key);
             if ((where != end()) && !value_comp()(key, *where))
+            {
                 return where;
-            else
-                return end();
+            }
+            return end();
         }
 
         template <class KeyType>
@@ -117,9 +118,10 @@ namespace frozen
         {
             auto const lower = lower_bound(key);
             if (lower == end())
+            {
                 return { lower, lower };
-            else
-                return { lower, lower + 1 };
+            }
+            return { lower, lower + 1 };
         }
 
         template <class KeyType>
@@ -127,9 +129,10 @@ namespace frozen
         {
             auto const where = bits::lower_bound<N>(keys_.begin(), key, value_comp());
             if ((where != end()) && !value_comp()(key, *where))
+            {
                 return where;
-            else
-                return end();
+            }
+            return end();
         }
 
         template <class KeyType>
@@ -137,9 +140,10 @@ namespace frozen
         {
             auto const where = bits::lower_bound<N>(keys_.begin(), key, value_comp());
             if ((where != end()) && !value_comp()(key, *where))
+            {
                 return where + 1;
-            else
-                return end();
+            }
+            return end();
         }
 
         /* observers */
diff --git a/include/frozen/unordered_set.h b/include/frozen/unordered_set.h
index 2385518..e38fcc8 100644
--- a/include/frozen/unordered_set.h
+++ b/include/frozen/unordered_set.h
@@ -35,7 +35,6 @@
 #include "bits/basic_types.h"
 #include "bits/elsa.h"
 #include "bits/pmh.h"
-#include "bits/version.h"
 #include "random.h"
 
 #include <functional>
@@ -50,7 +49,7 @@ namespace frozen
         struct Get
         {
             template <class T>
-            constexpr T const& operator()(T const& key) const
+            constexpr auto operator()(T const& key) const -> T const&
             {
                 return key;
             }
@@ -85,7 +84,6 @@ namespace frozen
         using const_iterator = typename container_type::const_iterator;
         using iterator = const_iterator;
 
-    public:
         /* constructors */
         unordered_set(unordered_set const&) = default;
         constexpr unordered_set(container_type keys, Hash const& hash, KeyEqual const& equal) :
@@ -111,72 +109,79 @@ namespace frozen
         }
 
         /* iterators */
-        [[nodiscard]] constexpr const_iterator begin() const { return keys_.begin(); }
-        [[nodiscard]] constexpr const_iterator end() const { return keys_.end(); }
-        [[nodiscard]] constexpr const_iterator cbegin() const { return keys_.begin(); }
-        [[nodiscard]] constexpr const_iterator cend() const { return keys_.end(); }
+        [[nodiscard]] constexpr auto begin() const -> const_iterator { return keys_.begin(); }
+        [[nodiscard]] constexpr auto end() const -> const_iterator { return keys_.end(); }
+        [[nodiscard]] constexpr auto cbegin() const -> const_iterator { return keys_.begin(); }
+        [[nodiscard]] constexpr auto cend() const -> const_iterator { return keys_.end(); }
 
         /* capacity */
-        [[nodiscard]] constexpr bool empty() const { return !N; }
-        [[nodiscard]] constexpr size_type size() const { return N; }
-        [[nodiscard]] constexpr size_type max_size() const { return N; }
+        [[nodiscard]] constexpr auto empty() const -> bool { return !N; }
+        [[nodiscard]] constexpr auto size() const -> size_type { return N; }
+        [[nodiscard]] constexpr auto max_size() const -> size_type { return N; }
 
         /* lookup */
         template <class KeyType>
-        [[nodiscard]] constexpr std::size_t count(KeyType const& key) const
+        [[nodiscard]] constexpr auto count(KeyType const& key) const -> std::size_t
         {
             return find(key, hash_function(), key_eq()) != end();
         }
 
         template <class KeyType, class Hasher, class Equal>
-        [[nodiscard]] constexpr const_iterator find(KeyType const& key, Hasher const& hash,
-                                                    Equal const& equal) const
+        [[nodiscard]] constexpr auto find(KeyType const& key, Hasher const& hash,
+                                          Equal const& equal) const -> const_iterator
         {
             auto const pos = tables_.lookup(key, hash);
-            auto it = keys_.begin() + pos;
-            if (it != keys_.end() && equal(*it, key))
-                return it;
-            else
-                return keys_.end();
+            auto iter = keys_.begin() + pos;
+            if (iter != keys_.end() && equal(*iter, key))
+            {
+                return iter;
+            }
+            return keys_.end();
         }
+
         template <class KeyType>
-        [[nodiscard]] constexpr const_iterator find(KeyType const& key) const
+        [[nodiscard]] constexpr auto find(KeyType const& key) const -> const_iterator
         {
             auto const pos = tables_.lookup(key, hash_function());
-            auto it = keys_.begin() + pos;
-            if (it != keys_.end() && key_eq()(*it, key))
-                return it;
-            else
-                return keys_.end();
+            auto iter = keys_.begin() + pos;
+            if (iter != keys_.end() && key_eq()(*iter, key))
+            {
+                return iter;
+            }
+            return keys_.end();
         }
 
         template <class KeyType>
-        [[nodiscard]] constexpr bool contains(KeyType const& key) const
+        [[nodiscard]] constexpr auto contains(KeyType const& key) const -> bool
         {
             return this->find(key) != keys_.end();
         }
 
         template <class KeyType>
-        [[nodiscard]] constexpr std::pair<const_iterator, const_iterator>
-            equal_range(KeyType const& key) const
+        [[nodiscard]] constexpr auto equal_range(KeyType const& key) const
+            -> std::pair<const_iterator, const_iterator>
         {
-            auto const it = find(key);
-            if (it != end())
-                return { it, it + 1 };
-            else
-                return { keys_.end(), keys_.end() };
+            auto const iter = find(key);
+            if (iter != end())
+            {
+                return { iter, iter + 1 };
+            }
+            return { keys_.end(), keys_.end() };
         }
 
         /* bucket interface */
-        [[nodiscard]] constexpr std::size_t bucket_count() const { return storage_size; }
-        [[nodiscard]] constexpr std::size_t max_bucket_count() const { return storage_size; }
+        [[nodiscard]] constexpr auto bucket_count() const -> std::size_t { return storage_size; }
+        [[nodiscard]] constexpr auto max_bucket_count() const -> std::size_t
+        {
+            return storage_size;
+        }
 
         /* observers*/
-        [[nodiscard]] constexpr const hasher& hash_function() const
+        [[nodiscard]] constexpr auto hash_function() const -> const hasher&
         {
             return tables_.hash_function();
         }
-        [[nodiscard]] constexpr const key_equal& key_eq() const
+        [[nodiscard]] constexpr auto key_eq() const -> const key_equal&
         {
             return static_cast<KeyEqual const&>(*this);
         }

From d0b70b1d8935d190055641ac1bcf33072ec0169b Mon Sep 17 00:00:00 2001
From: Randalphwa <38287198+Randalphwa@users.noreply.github.com>
Date: Fri, 3 Apr 2026 08:38:36 -0700
Subject: [PATCH 4/4] Allow draft versions of C++23
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

202302L is the final C++23 value. Apple Clang (even when compiling with -std=c++23 or -std=c++2b) sets __cplusplus to a draft value like 202101L or 202302L depending on the Clang version. Older Apple Clang versions that ship with macOS (which lag significantly behind upstream LLVM) commonly report 202101L — a C++23 draft value — rather than the ratified 202302L.
---
 include/frozen/algorithm.h     | 2 +-
 include/frozen/bits/version.h  | 2 +-
 include/frozen/map.h           | 2 +-
 include/frozen/random.h        | 2 +-
 include/frozen/set.h           | 2 +-
 include/frozen/string.h        | 2 +-
 include/frozen/unordered_map.h | 2 +-
 include/frozen/unordered_set.h | 2 +-
 8 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/frozen/algorithm.h b/include/frozen/algorithm.h
index 6b92bac..7e02c5a 100644
--- a/include/frozen/algorithm.h
+++ b/include/frozen/algorithm.h
@@ -28,7 +28,7 @@
         #error \
             "frozen/algorithm.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/algorithm.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/bits/version.h b/include/frozen/bits/version.h
index a6278df..0d1e83f 100644
--- a/include/frozen/bits/version.h
+++ b/include/frozen/bits/version.h
@@ -27,7 +27,7 @@
     #if _MSVC_LANG < 202302L
         #error "frozen 2.0 requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen 2.0 requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/map.h b/include/frozen/map.h
index 73260f6..74dbcae 100644
--- a/include/frozen/map.h
+++ b/include/frozen/map.h
@@ -27,7 +27,7 @@
     #if _MSVC_LANG < 202302L
         #error "frozen/map.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/map.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/random.h b/include/frozen/random.h
index 88e2df5..3c3681c 100644
--- a/include/frozen/random.h
+++ b/include/frozen/random.h
@@ -27,7 +27,7 @@
     #if _MSVC_LANG < 202302L
         #error "frozen/random.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/random.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/set.h b/include/frozen/set.h
index a79b300..dee8f0e 100644
--- a/include/frozen/set.h
+++ b/include/frozen/set.h
@@ -27,7 +27,7 @@
     #if _MSVC_LANG < 202302L
         #error "frozen/set.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/set.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/string.h b/include/frozen/string.h
index dc4cf90..ff2d85b 100644
--- a/include/frozen/string.h
+++ b/include/frozen/string.h
@@ -6,7 +6,7 @@
         #error \
             "frozen/unordered_map.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/unordered_map.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/unordered_map.h b/include/frozen/unordered_map.h
index 56d888d..13e33e1 100644
--- a/include/frozen/unordered_map.h
+++ b/include/frozen/unordered_map.h
@@ -28,7 +28,7 @@
         #error \
             "frozen/unordered_map.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/unordered_map.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif
 
diff --git a/include/frozen/unordered_set.h b/include/frozen/unordered_set.h
index e38fcc8..c0e151a 100644
--- a/include/frozen/unordered_set.h
+++ b/include/frozen/unordered_set.h
@@ -28,7 +28,7 @@
         #error \
             "frozen/unordered_set.h requires C++23 or later. Compile with /std:c++latest or /std:c++23."
     #endif
-#elif __cplusplus < 202302L
+#elif __cplusplus < 202101L
     #error "frozen/unordered_set.h requires C++23 or later. Compile with -std=c++23 or later."
 #endif