Re: [petsc-dev] need for HDF5 < 1.8.0 support?

[Smith, Barry F. via petsc-dev]

> On Dec 7, 2018, at 2:25 PM, Jed Brown <j...@jedbrown.org> wrote:
> 
> "Smith, Barry F." <bsm...@mcs.anl.gov> writes:
> 
>>> On Dec 7, 2018, at 8:56 AM, Jed Brown <j...@jedbrown.org> wrote:
>>> 
>>> "Smith, Barry F." <bsm...@mcs.anl.gov> writes:
>>> 
>>>> A potential drawback is some users also use HDF5 directly in their code 
>>>> and may be using an older version (people are very slow to change).
>>> 
>>> The HDF5 developers were very deliberate about this.  You can still use
>>> the old API in your own code while linking to the new library.  See
>>> H5_USE_16_API.
>>> 
>>> https://support.hdfgroup.org/HDF5/doc/RM/APICompatMacros.html
>> 
>>   This pages is a firehose. Most people who have HDF5 in their code (that 
>> someone else probably wrote) will never get through this page to know what 
>> to do. 

> 
> You literally just compile that old code using -DH5_USE_16_API while using 
> new HDF5 libraries and headers.

  Where do you put this -DH5_USE_16_API thing? I literally don't have a clue 
how my build system works. I would rather just stick to the old version since 
its worked for the last n years. (This is the average user/developer of 
package/application A)



>  
>>    I'm fine with removing the older versions if everyone else is but I 
>> definitely remember this exact issue occurring in the past; perhaps now HDF5 
>> has resolved it somewhere in their firehose.
>> 
>>   Barry