again

luakiwi/luakiwi-int.h

@@ -80,6 +80,11 @@ struct KiwiExpression {
    double constant;
    int term_count;
    Constraint* owner;
+   // https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
+   // Although using one-element arrays this way is discouraged, GCC handles accesses to
+   // trailing one-element array members analogously to zero-length arrays.
+   // The only reason avoiding FAM here is to support older MSVC.
+   // Otherwise this is a non-issue.
    KiwiTerm terms[1];
 };
 

luakiwi/luakiwi.cpp

@@ -1308,9 +1308,8 @@ static int lkiwi_solver_dumps(lua_State* L) {
    return 1;
 }
 
-typedef const KiwiErr* (*add_remove_fn_t)(lua_State*, KiwiSolver*, void*);
-
-static int lkiwi_add_remove_tab(lua_State* L, add_remove_fn_t fn, void* d) {
+template<typename F>
+static int lkiwi_add_remove_tab(lua_State* L, F&& fn) {
    KiwiSolver* solver = get_solver(L, 1);
    int narg = lua_gettop(L);
 
@@ -1322,10 +1321,10 @@ static int lkiwi_add_remove_tab(lua_State* L, add_remove_fn_t fn, void* d) {
       if (lua_geti(L, 2, i) == LUA_TNIL) {
          break;
       }
-      const KiwiErr* err = fn(L, solver, d);
+      const KiwiErr* err = fn(L, solver);
       if (err) {
          error_new(L, err, 1, narg + 1 /* item_absi */);
-         unsigned error_mask = solver->error_mask;
+         const auto error_mask = solver->error_mask;
          if (error_mask & (1 << err->kind)) {
             lua_replace(L, 3);
             lua_settop(L, 3);
@@ -1340,37 +1339,29 @@ static int lkiwi_add_remove_tab(lua_State* L, add_remove_fn_t fn, void* d) {
    return 1;
 }
 
-static const KiwiErr* add_constraint_fn(lua_State* L, KiwiSolver* s, void*) {
-   return kiwi_solver_add_constraint(s->solver, *get_constraint(L, -1));
-}
-
 static int lkiwi_solver_add_constraints(lua_State* L) {
-   return lkiwi_add_remove_tab(L, add_constraint_fn, 0);
-}
-
-static const KiwiErr* remove_constraint_fn(lua_State* L, KiwiSolver* s, void*) {
-   return kiwi_solver_remove_constraint(s->solver, *get_constraint(L, -1));
+   return lkiwi_add_remove_tab(L, [](lua_State* L, KiwiSolver* s) {
+      return kiwi_solver_add_constraint(s->solver, *get_constraint(L, -1));
+   });
 }
 
 static int lkiwi_solver_remove_constraints(lua_State* L) {
-   return lkiwi_add_remove_tab(L, remove_constraint_fn, 0);
-}
-
-static const KiwiErr* add_edit_var_fn(lua_State* L, KiwiSolver* s, void* d) {
-   return kiwi_solver_add_edit_var(s->solver, *get_var(L, -1), *(double*)d);
+   return lkiwi_add_remove_tab(L, [](lua_State* L, KiwiSolver* s) {
+      return kiwi_solver_add_constraint(s->solver, *get_constraint(L, -1));
+   });
 }
 
 static int lkiwi_solver_add_edit_vars(lua_State* L) {
    double strength = luaL_checknumber(L, 3);
-   return lkiwi_add_remove_tab(L, add_edit_var_fn, &strength);
-}
-
-static const KiwiErr* remove_edit_var_fn(lua_State* L, KiwiSolver* s, void*) {
-   return kiwi_solver_remove_edit_var(s->solver, *get_var(L, -1));
+   return lkiwi_add_remove_tab(L, [strength](lua_State* L, KiwiSolver* s) {
+      return kiwi_solver_add_edit_var(s->solver, *get_var(L, -1), strength);
+   });
 }
 
 static int lkiwi_solver_remove_edit_vars(lua_State* L) {
-   return lkiwi_add_remove_tab(L, remove_edit_var_fn, 0);
+   return lkiwi_add_remove_tab(L, [](lua_State* L, KiwiSolver* s) {
+      return kiwi_solver_remove_edit_var(s->solver, *get_var(L, -1));
+   });
 }
 
 static int lkiwi_solver_suggest_values(lua_State* L) {