[PATCH] [gdb/build] Fix static cast of virtual base

[Tom Tromey]

>>>>> "Simon" == Simon Marchi <simon.marchi@polymtl.ca> writes:

>> -  T result = dynamic_cast<T> (v);
>> -  gdb_assert (result != nullptr);
>> +  gdb_assert (dynamic_cast<T> (v) != nullptr);
>> +
>> +  /* If a base class of V is virtual then the dynamic_cast will succeed,
>> +     but the production mode static_cast will fail.  So having checked with
>> +     the dynamic_cast that we didn't get nullptr, now use static_cast to
>> +     catch the virtual base case.  This has the side effect of guaranteeing
>> +     that GDB will compile in production mode.  */
>> +  T result = static_cast<T> (v);
>> #else
>> T result = static_cast<T> (v);
>> #endif
>> 

Simon> This is similar to what I proposed here:

Simon> https://inbox.sourceware.org/gdb-patches/24af4ea8-5426-4ce4-b1c5-12858b38a952@simark.ca/

Simon> The idea is the same, to have a static_cast in the DEVELOPMENT branch.
Simon> I kinda like my version better, as it factors out the static cast
Simon> (notice that both branches have identical static_cast lines after your
Simon> patch) and the  ifdef is just around a single assert.  Also, I'm pretty
Simon> sure the nullptr check is not necessary, as both dynamic_cast and
Simon> static_cast can handle it.

I think either of these would be fine.

Tom