feedback on 2.69b

[Peter Eisentraut]

Here is some feedback on applying the 2.69b beta on the PostgreSQL 
source tree.  Basically, everything worked fine.

One issue we would like to point out is that the new scheme of 
automatically checking for the latest version of the C and C++ standards 
(deprecating AC_PROG_CC_C99 etc.) is problematic in two ways.

First, we have set C99 as the project standard.  So checking for C11 is 
(a) useless, and (b) bad because we don't want developers to 
accidentally make use of C11 features and have the compiler accept them 
silently.

Second, the additional tests for C11 and C++11 are slow.  This entirely 
eliminates all the performance improvements made elsewhere.  In 
particular, the test

checking for g++ option to enable C++11 features... none needed

takes on the order of 10 seconds for some developers.  And that is for 
one loop, since "none needed"; good luck if you need more than none.

It looks like it's not easy to disable these tests even with low-level 
hackery.  It would be better if there were still a way to set the 
preferred level of C and C++ in an official way.