Re: [PATCH] gdb/fortran: Handle dynamic string types when printing types

[Andrew Burgess <andrew.burgess@embecosm.com>]

* Simon Marchi <simon.marchi@polymtl.ca> [2020-07-14 22:10:58 -0400]:

> On 2020-07-14 6:03 a.m., Andrew Burgess wrote:
> > After commit:
> > 
> >   commit 8c2e4e0689ea244d0ed979171a3d09c9176b8175
> >   Date:   Sun Jul 12 22:58:51 2020 -0400
> > 
> >       gdb: add accessors to struct dynamic_prop
> > 
> > An existing bug was exposed in the Fortran type printing code.  When
> > GDB is asked to print the type of a function that takes a dynamic
> > string argument GDB will try to read the upper bound of the string.
> > 
> > The read of the upper bound is written as:
> > 
> >     if (type->bounds ()->high.kind () == PROP_UNDEFINED)
> >       // Treat the upper bound as unknown.
> >     else
> >       // Treat the upper bound as known and constant.
> > 
> > However, this is not good enough.  When printing a function type the
> > dynamic argument types will not have been resolved.  As a result the
> > dynamic property is not PROP_UNDEFINED, but nor is it constant.
> > 
> > By rewriting this code to specifically check for the PROP_CONST case,
> > and treating all other cases as the upper bound being unknown we avoid
> > incorrectly treating the dynamic property as being constant.
> > 
> > gdb/ChangeLog:
> > 
> > 	* f-typeprint.c (f_type_print_base): Allow for dynamic types not
> > 	being resolved.
> > 
> > gdb/testsuite/ChangeLog:
> > 
> > 	* gdb.fortran/ptype-on-functions.exp: Add more tests.
> > 	* gdb.fortran/ptype-on-functions.f90: Likewise.
> 
> Thanks, FWIW this LGTM.

Thanks.

> 
> Just wondering, if there were no existing test that caught this, how did you
> find it?  In an external testsuite?

No, I was writing tests for another patch that's still WIP.  Honestly
I was surprised that this wasn't already covered.

Thanks,
Andrew