Investigate sol2 CI build issue (#648)

* trigger CI to see if sol2 example is reliably failing

* attempt patch from github comment

* fix patch

* add info to comment on patch

* run fix-format

* simplify patchfile

examples/sol2/CMakeLists.txt

@@ -8,7 +8,7 @@ include(../../cmake/CPM.cmake)
 
 CPMAddPackage(
   NAME lua
-  GIT_REPOSITORY https://github.com/lua/lua.git
+  GITHUB_REPOSITORY lua/lua
   VERSION 5.3.5
   DOWNLOAD_ONLY YES
 )
@@ -21,7 +21,13 @@ if(lua_ADDED)
   target_include_directories(lua SYSTEM PUBLIC $<BUILD_INTERFACE:${lua_SOURCE_DIR}>)
 endif()
 
-CPMAddPackage("gh:ThePhD/sol2@3.3.0")
+CPMAddPackage(
+  NAME sol2
+  GITHUB_REPOSITORY ThePhD/sol2
+  VERSION 3.3.0
+  # fix for clang 18.1.0, see https://github.com/ThePhD/sol2/issues/1581#issuecomment-2103463524
+  PATCHES fix_for_clang.patch
+)
 
 # ---- Executable ----
 

examples/sol2/fix_for_clang.patch

@@ -0,0 +1,18 @@
+diff -u a/include/sol/function_types_stateless.hpp b/include/types/function_types_stateless.hpp
+--- a/include/sol/function_types_stateless.hpp
++++ b/include/sol/function_types_stateless.hpp
+@@ -322,7 +322,13 @@ namespace sol { namespace function_detail {
+ 		}
+
+ 		template <bool is_yielding, bool no_trampoline>
+-		static int call(lua_State* L) noexcept(std::is_nothrow_copy_assignable_v<T>) {
++		static int call(lua_State* L)
++#if SOL_IS_ON(SOL_COMPILER_CLANG)
++		// apparent regression in clang 18 - llvm/llvm-project#91362
++#else
++			noexcept(std::is_nothrow_copy_assignable_v<T>)
++#endif
++		{
+ 			int nr;
+ 			if constexpr (no_trampoline) {
+ 				nr = real_call(L);