[patch, fortran] PR18923 segfault after subroutine name confusion

[Jerry DeLisle]

Tobias Burnus wrote:
> Jerry DeLisle wrote:
>> I would like to add this one additional change.  We need to give it up
>> at some point and one of these test cases triggers this.  It seems to
>> make sense to me.  Let me know if this is OK and I will include it. 
>> Regression tested of course and it obviously passes.
>> Index: symbol.c
>> -     gfc_internal_error ("gfc_get_default_type(): Bad symbol");
>> +     gfc_fatal_error ("Symbol name confusion at %C");
> 
> Hmm, I like that it shows the position, but it only shows "Fatal Error:"
> instead of "Internal Compiler Error:". Internal errors should never
> happen (they are by definition a bug in the compiler) and should be
> reported.
> 
> "Fatal Error:" on the other hand sound more like user errors which
> should not be reported.
> 
> I think invalid user code should and are rejected earlier, namely in
> gfc_match ("Invalid character in name at %C"). Therefore, I would prefer
> an gfc_internal_error. Couldn't you use something like:
> 
>      gfc_internal_error ("gfc_get_default_type(): Bad symbol at %C");
> 
> this gives more debugging information but still implies the ICE. If I
> read error.c correctly, this should work.
> 
> Tobias
> 
This is one of those invalids where we ought to quit after the syntax error is 
found.  Instead we move on into resolve and get additional nonsense messages 
before finally hitting the internal error.  I have an upcoming patch, still 
being developed and tested to attempt to intercept these and bail out earlier.

I will commit the segfault fixes, then work on this new patch to catch the 
syntax and quit.  After that I will get the test cases in place.

Jerry