Re: [PATCH 0/5] glr.cc: support syntax_error exceptions

[Adrian Vogelsgesang]

Hi Akim,

if I might chime in here:
Looking at the generated lalr1 parser, it contains the code (shortened here in 
this email)
>     catch (...) {
>        if (!yyla.empty ()) yy_destroy_ (YY_NULLPTR, yyla);
>        while (1 < yystack_.size ()) {
>          yy_destroy_ (YY_NULLPTR, yystack_[0]);
>          yypop_ ();
>        }
>        throw;
>     }
which catches all exceptions and cleans up before rethrowing them.

This block seems to be missing in glr.cc (I didn't actually check the generated 
code, just had a look at the skeleton file, so maybe I am missing something 
here)

So, a non-syntax_error exception would bubble up through the GLR parser and 
could be caught outside the parser, just like in the LALR1 parser.
However, such an exception would leave the parser in a dirty state instead of 
doing the necessary cleanup.

@Askar: please correct me if I misunderstood the issue

Cheers,
Adrian


On 02/01/2019, 12:12, "bison-patches on behalf of Akim Demaille" 
<address@hidden on behalf of address@hidden> wrote:

    Hey Askar,
    
    > Le 2 janv. 2019 à 01:49, Askar Safin <address@hidden> a écrit :
    > 
    > Also, I looked into generated .tab.cpp files and saw that LALR1 parser 
have "catch (...)" and GLR parser doesn't have "catch (...)". So, it seems GLR 
parser will support syntax_error exceptions only, but not all other exceptions 
(i. e. GLR parser will not rethrow non-syntax_error exceptions correctly, 
unlike LALR1 parser).
    
    Your sentence is confusing.  It seems you are saying that the other 
exceptions will be blocked, which is of course not what is going to happen.
    
    > And this is _very_ strange.
    
    Less than this comment :)
    
    > At least user should be warned about such very strange behavior in docs.
    
    Contributions are most welcome.  As always.