[Enigma-devel] crashes on linux gcc exception handling

[Ronald Lamprecht]

Hi,

after solving our Windows gcc crashes Andreas did report another problem 
that results in crashes on Linux and likely on Mac, too. (Windows is not 
affected as our workaround solves this problem on the fly)

Enigma's engine throws C++ "XRuntime" exceptions on errors during 
execution of a level. They should be caught and the level should be 
aborted with an error message instead a crash of Enigma.

These exceptions can occur anywhere in the engine and with the switch 
from the old fashioned "assert", that did cause an app crash either way, 
to exception based "ASSERT"-macros we did increase the likelyhood of 
exceptions.

If such a runtime exception is thrown with C longjump-based Lua frames 
on the execution stack the C++ exception will not unwind to the catch 
statement but crash the app within gcc internal code (f.e. the appended 
diff causes all levels with triggers to throw exceptions on load).

This behaviour may be within some gcc specs or it may be a bug. But it 
is at least very annoying.

In general there are two Enigma internal solutions:

1. write an own unwind that catches all C++ exceptions before returning 
via Lua and rethrow the exceptions after returnung to C++.

2. switch Lua to C++ for Linux and other OS, too

As approach 1. means a lot of work and would force a rewrite of all 
tolua based code I would prefer the second solution.

Is anyone aware of other solutions? Does anyone object solution 2?

- Ronald

Index: src/items.cc
===================================================================
--- src/items.cc        (revision 302)
+++ src/items.cc        (working copy)
@@ -1315,6 +1315,7 @@
 
 void Trigger::init_model()
 {
+    ASSERT(0, XLevelRuntime, "Assert did not fail.");
     if (int_attrib("invisible"))
         set_model("invisible");
     else if (m_pressedp)