On 12 Dec 2017, at 15:30, Lobron, David <[email protected]> wrote:
>
> I tweaked my code a bit. I now have an ObjC class in a .m file that throws
> an exception like this:
>
> - (void)poke
> {
> [NSException raise:@"Exception" format:@"Exception"];
> }
This doesn’t add anything, because the exception is thrown from the NSException
-raise method, which is ObjC and will do a @throw from an ObjC compilation unit
inside -base. For a libobjc2 test, I’ll need it to not depend on -base at all
when I add it to the test suite.
> I call this from a .m file, inside an NS_HANDLER, and then re-raise the
> exception. The goal here is to pass the NSException through a plain ObjC
> frame:
>
> - (void)poke
> {
> NS_DURING
> [_oc poke];
> NS_HANDLER
> NSLog(@"Caught second exception");
> [localException raise];
> NS_ENDHANDLER
> }
This is easier to read if you don’t use the macros. Now you’re doing
@catch(id), which is catching the exception. You’re then throwing it again
(@throw inside the -raise method), rather that rethrowing it (@throw with no
argument). This wants to be an @finally though, because we’re looking for a
case where the search phase and the unwinding phase do different things.
>
> Finally, I call this from a .mm file, inside a C++ class method:
>
> void tryCpp() {
> Tester *t = [[Tester new] autorelease];
> try {
> try {
> NSLog(@"tryCpp starting");
> [t poke];
> } catch(NSException *e) {
> NSLog(@"tryCpp aught ObjC exception");
> throw e;
> }
> } catch(...) {
> NSLog(@"tryCpp caught outer exception");
> }
> }
>
> The goal here is to do what you suggested above, namely, force the ObjC
> runtime to turn the NSException into a C++ exception for delivery to the
> tryCpp method, which is a plain C++ instance method. But the debug output
> (copied below) suggests that is not happening: all of the exception
> personalities are of class GNUCOBJC. Am I missing a step here, or not
> understanding the way exception personalities are passed through frames? I'm
> still learning this, so maybe I'm missing something obvious.
Try to recreate the structure of your original failure with the same mix of
ObjC/C++/ObjC++ stack frames and the same cleanups / catches.
David
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