SWORD25: Replace calls to LUAI_THROW() with error() in LUA

This removes one of the uses of setjmp(), but its use in LUAI_TRY still
remains

3 files changed, 20 insertions, 16 deletions

diff --git a/engines/sword25/util/lua/ldo.cpp b/engines/sword25/util/lua/ldo.cpp
index 5d9667f4f0..33ed3255a3 100644
--- a/engines/sword25/util/lua/ldo.cpp
+++ b/engines/sword25/util/lua/ldo.cpp
@@ -6,12 +6,10 @@
 
 
 // FIXME: LUAI_THROW and LUAI_TRY use either throw/catch or setjmp/longjmp.
-// Neither of these is supported in ScummVM. So we need to come up
-// with a replacement. The most simple, direct and crude approach:
-// Replace "throw" with an "error()" call. Of course we only
-// would want to do that if this actually never happens...
-#define FORBIDDEN_SYMBOL_EXCEPTION_setjmp
-#define FORBIDDEN_SYMBOL_EXCEPTION_longjmp
+// Neither of these is supported in ScummVM. Calls to LUAI_THROW have been
+// replaced with error() in ScummVM, but the calls to LUAI_TRY remain
+#define FORBIDDEN_SYMBOL_EXCEPTION_setjmp	// for LUAI_TRY, i.e. try()
+#define FORBIDDEN_SYMBOL_EXCEPTION_longjmp	// for LUAI_TRY and LUAI_THROW, i.e. throw()
 
 #include "common/textconsole.h"
 
@@ -103,12 +101,10 @@ static void resetstack (lua_State *L, int status) {
 void luaD_throw (lua_State *L, int errcode) {
   if (L->errorJmp) {
     L->errorJmp->status = errcode;
-    // FIXME: LUAI_THROW and LUAI_TRY use either throw/catch or setjmp/longjmp.
-    // Neither of these is supported in ScummVM. So we need to come up
-    // with a replacement. The most simple, direct and crude approach:
-    // Replace "throw" with an "error()" call. Of course we only
-    // would want to do that if this actually never happens...
-    LUAI_THROW(L, L->errorJmp);
+	// LUAI_THROW has been replaced with an error message in ScummVM, together
+	// with the LUA error code and description
+    //LUAI_THROW(L, L->errorJmp);
+	error("LUA error occured, error code is %d (%s)", errcode, luaErrorDescription[errcode]);
   }
   else {
     L->status = cast_byte(errcode);
@@ -129,9 +125,8 @@ int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
   L->errorJmp = &lj;
   // FIXME: LUAI_THROW and LUAI_TRY use either throw/catch or setjmp/longjmp.
   // Neither of these is supported in ScummVM. So we need to come up
-  // with a replacement. The most simple, direct and crude approach:
-  // Replace "throw" with an "error()" call. Of course we only
-  // would want to do that if this actually never happens...
+  // with a replacement. Calls to LUAI_THROW have been replaced with error()
+  // in ScummVM, but the calls to LUAI_TRY remain
   LUAI_TRY(L, &lj,
     (*f)(L, ud);
   );
diff --git a/engines/sword25/util/lua/lua.h b/engines/sword25/util/lua/lua.h
index 08ad80d70f..768ec1ad74 100644
--- a/engines/sword25/util/lua/lua.h
+++ b/engines/sword25/util/lua/lua.h
@@ -48,6 +48,15 @@
 #define LUA_ERRMEM	4
 #define LUA_ERRERR	5
 
+// Added in ScummVM. Refer to http://www.lua.org/manual/5.1/manual.html
+static const char* luaErrorDescription[] = {
+	"No error",
+	"Coroutine yield",	// not an actual error, see lua_resume
+	"Runtime error",
+	"Syntax error during pre-compilation",	// refer to lua_load
+	"Memory allocation error",
+	"Error while running the error handler function"
+};
 
 typedef struct lua_State lua_State;
 
diff --git a/engines/sword25/util/lua/luaconf.h b/engines/sword25/util/lua/luaconf.h
index 53d0f55290..fb85983998 100644
--- a/engines/sword25/util/lua/luaconf.h
+++ b/engines/sword25/util/lua/luaconf.h
@@ -621,7 +621,7 @@ union luai_Cast { double l_d; long l_l; };
 
 #else
 /* default handling with long jumps */
-#define LUAI_THROW(L,c)	longjmp((c)->b, 1)
+//#define LUAI_THROW(L,c)	longjmp((c)->b, 1)	// replaced with error() in ScummVM
 #define LUAI_TRY(L,c,a)	if (setjmp((c)->b) == 0) { a }
 #define luai_jmpbuf	jmp_buf