From 0068f6c0fda6b270c9e7481a17a7d0556be15f60 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <roland@roly-laptop-21.localdomain>
Date: Thu, 19 Oct 2023 00:00:41 -0400
Subject: [PATCH 1/2] build: concept carveout for clang + std::copyable

---
 include/xo/randomgen/distribution_concept.hpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/xo/randomgen/distribution_concept.hpp b/include/xo/randomgen/distribution_concept.hpp
index 61c764e0..979a64d5 100644
--- a/include/xo/randomgen/distribution_concept.hpp
+++ b/include/xo/randomgen/distribution_concept.hpp
@@ -24,12 +24,16 @@ namespace xo {
             // os << dist
             // is >> dist
 
-        } && std::copyable<Distribution>
+        }
+#ifdef __clang__
+        // std::copyable apparently not available in clang11 ?
+#else
+        && std::copyable<Distribution>
         && std::copyable<typename Distribution::param_type>
+#endif
         && std::equality_comparable<typename Distribution::param_type>;
     } /*namespace rng*/
 
 } /*namespace xo*/
 
-
 /* end distribution_concept.hpp */

From a6d0252dd46c19772370fab8e752c15497f0ca64 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <roland@roly-laptop-21.localdomain>
Date: Thu, 19 Oct 2023 12:15:18 -0400
Subject: [PATCH 2/2] build: clang16 fixes (c++20 concept headers available)

---
 include/xo/randomgen/distribution_concept.hpp | 3 ++-
 include/xo/randomgen/engine_concept.hpp       | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/xo/randomgen/distribution_concept.hpp b/include/xo/randomgen/distribution_concept.hpp
index 979a64d5..c2343255 100644
--- a/include/xo/randomgen/distribution_concept.hpp
+++ b/include/xo/randomgen/distribution_concept.hpp
@@ -30,8 +30,9 @@ namespace xo {
 #else
         && std::copyable<Distribution>
         && std::copyable<typename Distribution::param_type>
+        && std::equality_comparable<typename Distribution::param_type>
 #endif
-        && std::equality_comparable<typename Distribution::param_type>;
+        ;
     } /*namespace rng*/
 
 } /*namespace xo*/
diff --git a/include/xo/randomgen/engine_concept.hpp b/include/xo/randomgen/engine_concept.hpp
index 38b65cd7..2b3a2e53 100644
--- a/include/xo/randomgen/engine_concept.hpp
+++ b/include/xo/randomgen/engine_concept.hpp
@@ -7,6 +7,8 @@
 
 namespace std {
 #ifdef __clang__
+
+# if __clang_major__ <= 11
     template < class T >
     concept integral = std::is_integral_v<T>;
 
@@ -31,8 +33,11 @@ namespace std {
         && requires { { G::min() } -> std::same_as<std::invoke_result_t<G&>>;
                       { G::max() } -> std::same_as<std::invoke_result_t<G&>>;
                       requires std::bool_constant<(G::min() < G::max())>::value; };
+# endif
+
 #else
     /* uniform_random_bit_generator provided by gcc 12.3.2 */
+    /* uniform_random_bit_generator provided by clang 16 */
 #endif
 } /*namespace std*/