Fix: Build clean under -Wall -Wextra -Werror

Give the C-ABI `visit` switch a trailing return so it is total for -Wreturn-type, and bound the pool-name copy with an explicit length instead of strncpy, which -Werror=stringop-truncation rejects on the exact-fit case.

c/forkunion.cpp

@@ -153,6 +153,7 @@ result_type_ visit(visitor_type_ &&visitor, pool_variants_t &variants, result_ty
     case fu::pool_kind_t::flat_k: return visit_kind<fu::pool_kind_t::flat_k>(visitor, variants);
     case fu::pool_kind_t::unknown_k: return empty;
     }
+    return empty; // An out-of-enum `kind_` is undefined behavior upstream; stay total for `-Wreturn-type`.
 }
 
 /** @brief Runs @p visitor on the live pool for its side effects; a no-op on empty storage. */

include/forkunion/distributed.hpp

@@ -209,8 +209,10 @@ struct colocated_pool {
     explicit colocated_pool(char const *name = "forkunion") noexcept {
         // Accept NULL or empty names by falling back to a sensible default
         char const *effective_name = (name && name[0] != '\0') ? name : "forkunion";
-        std::strncpy(name_, effective_name, sizeof(name_) - 1);
-        name_[sizeof(name_) - 1] = '\0';
+        std::size_t const source_length = std::strlen(effective_name);
+        std::size_t const name_length = source_length < sizeof(name_) ? source_length : sizeof(name_) - 1;
+        std::memcpy(name_, effective_name, name_length);
+        name_[name_length] = '\0';
     }
 
     ~colocated_pool() noexcept { terminate(); }
@@ -1132,8 +1134,10 @@ struct distributed_pool {
     explicit distributed_pool(char const *name) noexcept {
         // Accept null or empty names by falling back to a sensible default
         char const *effective_name = (name && name[0] != '\0') ? name : "forkunion";
-        std::strncpy(name_, effective_name, sizeof(name_) - 1);
-        name_[sizeof(name_) - 1] = '\0';
+        std::size_t const source_length = std::strlen(effective_name);
+        std::size_t const name_length = source_length < sizeof(name_) ? source_length : sizeof(name_) - 1;
+        std::memcpy(name_, effective_name, name_length);
+        name_[name_length] = '\0';
     }
 
     ~distributed_pool() noexcept { terminate(); }