8 files changed, 44 insertions, 35 deletions

diff --git a/src/cancel.cpp b/src/cancel.cpp
index 73e50f5..c0867a9 100644
--- a/src/cancel.cpp
+++ b/src/cancel.cpp
@@ -50,7 +50,7 @@ THE SOFTWARE.
 * Called by cancellation hooks and/or pending Linda operations (because then
 * the check won't affect performance).
 *
-* Returns CANCEL_SOFT/HARD if any locks are to be exited, and 'cancel_error()' called,
+* Returns CANCEL_SOFT/HARD if any locks are to be exited, and 'raise_cancel_error()' called,
 * to make execution of the lane end.
 */
 static inline CancelRequest cancel_test(lua_State* L)
@@ -78,13 +78,13 @@ LUAG_FUNC( cancel_test)
 // ################################################################################################
 // ################################################################################################
 
-static void cancel_hook( lua_State* L, [[maybe_unused]] lua_Debug* ar)
+static void cancel_hook(lua_State* L, [[maybe_unused]] lua_Debug* ar)
 {
-    DEBUGSPEW_CODE( fprintf( stderr, "cancel_hook\n"));
+    DEBUGSPEW_CODE(fprintf(stderr, "cancel_hook\n"));
     if (cancel_test(L) != CancelRequest::None)
     {
-        lua_sethook( L, nullptr, 0, 0);
-        cancel_error( L);
+        lua_sethook(L, nullptr, 0, 0);
+        raise_cancel_error(L);
     }
 }
 
@@ -158,7 +158,7 @@ static CancelResult thread_cancel_hard(lua_State* L, Lane* s, double secs_, bool
         result = THREAD_WAIT(&s->thread, waitkill_timeout_, &s->done_signal, &s->done_lock, &s->status) ? CancelResult::Killed : CancelResult::Timeout;
         if (result == CancelResult::Timeout)
         {
-            (void) luaL_error( L, "force-killed lane failed to terminate within %f second%s", waitkill_timeout_, waitkill_timeout_ > 1 ? "s" : "");
+            std::ignore = luaL_error( L, "force-killed lane failed to terminate within %f second%s", waitkill_timeout_, waitkill_timeout_ > 1 ? "s" : "");
         }
 #else
         (void) waitkill_timeout_; // unused
@@ -238,7 +238,7 @@ static CancelOp which_op( lua_State* L, int idx_)
         lua_remove( L, idx_); // argument is processed, remove it
         if( op == CO_Invalid)
         {
-            luaL_error( L, "invalid hook option %s", str);
+            std::ignore = luaL_error( L, "invalid hook option %s", str);
         }
         return op;
     }
diff --git a/src/cancel.h b/src/cancel.h
index 9a20774..9299ae1 100644
--- a/src/cancel.h
+++ b/src/cancel.h
@@ -46,18 +46,18 @@ enum CancelOp
 };
 
 // crc64/we of string "CANCEL_ERROR" generated at http://www.nitrxgen.net/hashgen/
-static constexpr UniqueKey CANCEL_ERROR{ 0xe97d41626cc97577ull }; // 'cancel_error' sentinel
+static constexpr UniqueKey CANCEL_ERROR{ 0xe97d41626cc97577ull }; // 'raise_cancel_error' sentinel
 
 // crc64/we of string "CANCEL_TEST_KEY" generated at http://www.nitrxgen.net/hashgen/
 static constexpr UniqueKey CANCEL_TEST_KEY{ 0xe66f5960c57d133aull }; // used as registry key
 
 CancelResult thread_cancel(lua_State* L, Lane* s, CancelOp op_, double secs_, bool force_, double waitkill_timeout_);
 
-static inline int cancel_error( lua_State* L)
+[[noreturn]] static inline void raise_cancel_error(lua_State* L)
 {
-    STACK_GROW( L, 1);
+    STACK_GROW(L, 1);
     CANCEL_ERROR.push(L); // special error value
-    return lua_error( L); // doesn't return
+    raise_lua_error(L); // doesn't return
 }
 
 // ################################################################################################
diff --git a/src/deep.cpp b/src/deep.cpp
index f59e051..74ecfb8 100644
--- a/src/deep.cpp
+++ b/src/deep.cpp
@@ -184,7 +184,7 @@ static int deep_userdata_gc( lua_State* L)
         // top was set to 0, then userdata was pushed. "delete" might want to pop the userdata (we don't care), but should not push anything!
         if ( lua_gettop( L) > 1)
         {
-            luaL_error( L, "Bad idfunc(eDO_delete): should not push anything");
+            return luaL_error( L, "Bad idfunc(eDO_delete): should not push anything");
         }
     }
     *proxy = nullptr; // make sure we don't use it any more, just in case
@@ -478,8 +478,8 @@ bool copydeep(Universe* U, lua_State* L2, int L2_cache_i, lua_State* L, int i, L
     if (errmsg != nullptr)
     {
         // raise the error in the proper state (not the keeper)
-        lua_State* errL = (mode_ == eLM_FromKeeper) ? L2 : L;
-        luaL_error( errL, errmsg);
+        lua_State* const errL { (mode_ == eLM_FromKeeper) ? L2 : L };
+        std::ignore = luaL_error(errL, errmsg);
     }
     return true;
 }
\ No newline at end of file
diff --git a/src/keeper.cpp b/src/keeper.cpp
index cb2b0a9..1919a68 100644
--- a/src/keeper.cpp
+++ b/src/keeper.cpp
@@ -655,7 +655,7 @@ void init_keepers(Universe* U, lua_State* L)
     lua_pop(L, 1);                                                 //
     if (nb_keepers < 1)
     {
-        (void) luaL_error(L, "Bad number of keepers (%d)", nb_keepers);
+        std::ignore = luaL_error(L, "Bad number of keepers (%d)", nb_keepers);
     }
 
     // Keepers contains an array of 1 Keeper, adjust for the actual number of keeper states
@@ -664,8 +664,7 @@ void init_keepers(Universe* U, lua_State* L)
         U->keepers = static_cast<Keepers*>(U->internal_allocator.alloc(bytes));
         if (U->keepers == nullptr)
         {
-            (void) luaL_error(L, "init_keepers() failed while creating keeper array; out of memory");
-            return;
+            std::ignore = luaL_error(L, "init_keepers() failed while creating keeper array; out of memory");
         }
         memset(U->keepers, 0, bytes);
         U->keepers->nb_keepers = nb_keepers;
@@ -677,7 +676,6 @@ void init_keepers(Universe* U, lua_State* L)
         if (K == nullptr)
         {
             std::ignore = luaL_error(L, "init_keepers() failed while creating keeper states; out of memory");
-            return;
         }
 
         U->keepers->keeper_array[i].L = K;
@@ -709,8 +707,7 @@ void init_keepers(Universe* U, lua_State* L)
             {
                 // if something went wrong, the error message is at the top of the stack
                 lua_remove(L, -2);                                 // error_msg
-                (void) lua_error(L);
-                return;
+                raise_lua_error(L);
             }
         }
         lua_pop(L, 1);                                             //
diff --git a/src/lanes.cpp b/src/lanes.cpp
index a378a88..2f17e6e 100644
--- a/src/lanes.cpp
+++ b/src/lanes.cpp
@@ -1110,7 +1110,7 @@ LUAG_FUNC( lane_new)
                 if( lua_isnil( L2, -1))
                 {
                     lua_pop( L2, 1);                                                                                                           //
-                    luaL_error( L, "cannot pre-require modules without loading 'package' library first");
+                    return luaL_error( L, "cannot pre-require modules without loading 'package' library first");
                 }
                 else
                 {
@@ -1119,7 +1119,7 @@ LUAG_FUNC( lane_new)
                     {
                         // propagate error to main state if any
                         luaG_inter_move( U, L2, L, 1, eLM_LaneBody); // func libs priority globals package required gc_cb [... args ...] n "modname" error
-                        return lua_error( L);
+                        raise_lua_error(L);
                     }
                     // after requiring the module, register the functions it exported in our name<->function database
                     populate_func_lookup_table( L2, -1, name);
@@ -1538,11 +1538,9 @@ LUAG_FUNC( thread_index)
                         lua_pushliteral( L, "Unexpected status: ");
                         lua_pushstring( L, thread_status_string( s));
                         lua_concat( L, 2);
-                        lua_error( L);
-                        break;
+                        raise_lua_error(L);
                     }
-                    // fall through if we are killed, as we got nil, "killed" on the stack
-                    [[fallthrough]];
+                    [[fallthrough]]; // fall through if we are killed, as we got nil, "killed" on the stack
 
                     case DONE: // got regular return values
                     {
diff --git a/src/linda.cpp b/src/linda.cpp
index 2830593..e1633b0 100644
--- a/src/linda.cpp
+++ b/src/linda.cpp
@@ -165,7 +165,7 @@ static void check_key_types(lua_State* L, int start_, int end_)
         {
             continue;
         }
-        (void) luaL_error( L, "argument #%d: invalid key type (not a boolean, string, number or light userdata)", i);
+        std::ignore = luaL_error(L, "argument #%d: invalid key type (not a boolean, string, number or light userdata)", i);
     }
 }
 
@@ -192,7 +192,7 @@ LUAG_FUNC(linda_protected_call)
     // if there was an error, forward it
     if( rc != LUA_OK)
     {
-        return lua_error( L);
+        raise_lua_error(L);
     }
     // return whatever the actual operation provided
     return lua_gettop( L);
@@ -339,7 +339,7 @@ LUAG_FUNC( linda_send)
 
         case CancelRequest::Hard:
         // raise an error interrupting execution only in case of hard cancel
-        return cancel_error( L); // raises an error and doesn't return
+        raise_cancel_error(L); // raises an error and doesn't return
 
         default:
         lua_pushboolean( L, ret); // true (success) or false (timeout)
@@ -494,7 +494,7 @@ LUAG_FUNC( linda_receive)
 
         case CancelRequest::Hard:
         // raise an error interrupting execution only in case of hard cancel
-        return cancel_error( L); // raises an error and doesn't return
+        raise_cancel_error(L); // raises an error and doesn't return
 
         default:
         return pushed;
diff --git a/src/macros_and_utils.h b/src/macros_and_utils.h
index 63bc8d1..31027d6 100644
--- a/src/macros_and_utils.h
+++ b/src/macros_and_utils.h
@@ -11,6 +11,7 @@ extern "C" {
 #endif // __cplusplus
 
 #include <cassert>
+#include <tuple>
 #include <type_traits>
 
 #define USE_DEBUG_SPEW() 0
@@ -71,7 +72,7 @@ class StackChecker
         if ((offset_ < 0) || (m_oldtop < 0))
         {
             assert(false);
-            (void) luaL_error(m_L, "STACK INIT ASSERT failed (%d not %d): %s:%d", lua_gettop(m_L), offset_, file_, line_);
+            std::ignore = luaL_error(m_L, "STACK INIT ASSERT failed (%d not %d): %s:%d", lua_gettop(m_L), offset_, file_, line_);
         }
     }
 
@@ -82,7 +83,7 @@ class StackChecker
         if (lua_gettop(m_L) != pos_)
         {
             assert(false);
-            (void) luaL_error(m_L, "STACK INIT ASSERT failed (%d not %d): %s:%d", lua_gettop(m_L), pos_, file_, line_);
+            std::ignore = luaL_error(m_L, "STACK INIT ASSERT failed (%d not %d): %s:%d", lua_gettop(m_L), pos_, file_, line_);
         }
     }
 
@@ -102,7 +103,7 @@ class StackChecker
             if (actual != expected_)
             {
                 assert(false);
-                luaL_error(m_L, "STACK ASSERT failed (%d not %d): %s:%d", actual, expected_, file_, line_);
+                std::ignore = luaL_error(m_L, "STACK ASSERT failed (%d not %d): %s:%d", actual, expected_, file_, line_);
             }
         }
     }
@@ -121,11 +122,15 @@ class StackChecker
 inline void STACK_GROW(lua_State* L, int n_)
 {
     if (!lua_checkstack(L, n_))
-        luaL_error(L, "Cannot grow stack!");
+    {
+        std::ignore = luaL_error(L, "Cannot grow stack!");
+    }
 }
 
 #define LUAG_FUNC( func_name) int LG_##func_name( lua_State* L)
 
+// #################################################################################################
+
 // a small helper to extract a full userdata pointer from the stack in a safe way
 template<typename T>
 T* lua_tofulluserdata(lua_State* L, int index_)
@@ -153,3 +158,12 @@ T* lua_newuserdatauv(lua_State* L, int nuvalue_)
 {
     return static_cast<T*>(lua_newuserdatauv(L, sizeof(T), nuvalue_));
 }
+
+// #################################################################################################
+
+// use this instead of Lua's lua_error if possible
+[[noreturn]] static inline void raise_lua_error(lua_State* L)
+{
+    std::ignore = lua_error(L); // doesn't return
+    assert(false); // we should never get here, but i'm paranoid
+}
diff --git a/src/state.cpp b/src/state.cpp
index 817d5b4..b52bdb5 100644
--- a/src/state.cpp
+++ b/src/state.cpp
@@ -82,7 +82,7 @@ static int luaG_new_require( lua_State* L)
 
     if( rc != LUA_OK) // LUA_ERRRUN / LUA_ERRMEM ?
     {
-        return lua_error( L);
+        raise_lua_error(L);
     }
     // should be 1 for Lua <= 5.3, 1 or 2 starting with Lua 5.4
     return lua_gettop(L);                                           // result(s)