[dmd-internals] changeset 455

[Robert Clipsham]

On 28/04/10 21:54, Andrei Alexandrescu wrote:
>> But surely once a process has been sent SIGSEGV, we can't really recover
>> from a generic handler? The process at that point is in an unknown
>> state. The correct behaviour on SIGSEGV is to die.
>
> I agree. But couldn't the process printf() a string before dying?

There's a GNU library for handling this, libsigsegv (
http://libsigsegv.sourceforge.net/ ). I took the liberty of downloading 
and inspecting this, it's 5659 LoC to handle segfaults (So say, 3000 if 
we rewrote it in D :P). That's a lot of extra code to handle a segfault 
for unittests. Add to this not all platforms support it, and it needs 
reimplementing on every platform. If you want this code in 
druntime/phobos then you'll have to write it from scratch due to 
licensing issues and be unable to look at this well written/tested 
library as a reference... It seems like a lot of extra effort for 
something I maintain should be done with a debugger.

Not to mention the fact that printing a string before dying is as good 
as useless. You know the order the unittests are being run, as you wrote 
the code... From this you can figure out which case is failing (unless 
it's the first test of an unknown file, but again, debugger). You just 
need to look what the last test case was to run before the segfault. 
Alternatively you could get the unittester to do something along the 
lines of:
----
writef( "%s:%d: ", file, line );
fflush(stdout);
writefln( "%s", runTest() == true ? "success" : "fail" );
----
Which would allow you to see the test that was being run before it runs.