Having a copy per version worked well until it was time to add new features or modify existing functions. Then it was necessary to modify every version and try to keep them all in sync.
Consolidate all the PostgreSQL types into a single file using #if for type versions. Many types do not change or change infrequently so this cuts down on duplication. In addition, it is far easier to see what has changed when a new version is added.
Use macros to write the interface functions. There is still duplication here since some changes require a new copy of the macro, but it is far less than before.
Move the documentation to postgres/interface.c so it can be updated without having to update N source files.
The "is" function was not very specific so rename to "controlIs".
This parameter was always useless but commit 7333b630 removed all references to it so remove the parameter at all call sites as well.
The original intention was probably to allow logging of TEST return values but that never happened.
Rename FUNCTION_DEBUG_* macros to FUNCTION_LOG_* to more accurately reflect what they do. Further rename FUNCTION_DEBUG_RESULT* macros to FUNCTION_LOG_RETURN* to make it clearer that they return from the function as well as logging. Leave FUNCTION_TEST_* macros as they are.
Consolidate the various ASSERT* macros into a single ASSERT macro that is always compiled out of production builds. It was difficult to figure out when an assert would be checked with all the different types in play. When ASSERTs are compiled in they will always be checked regardless of the log level -- tying these two concepts together was not a good idea.
PostgreSQL 11 introduces configurable WAL segment sizes, from 1MB to 1GB.
There are two areas that needed to be updated to support this: building the archive-get queue and checking that WAL has been archived after a backup. Both operations require the WAL segment size to properly build a list.
Checking the archive after a backup is still implemented in Perl and has an active database connection, so just get the WAL segment size from the database.
The archive-get command does not have a connection to the database, so get the WAL segment size from pg_control instead. This requires a deeper inspection of pg_control than has been done in the past, so it seemed best to copy the relevant data structures from each version of PostgreSQL and build a generic interface layer to address them. While this approach is a bit verbose, it has the advantage of being relatively simple, and can easily be updated for new versions of PostgreSQL.
Since the integration tests generate pg_control files for testing, teach Perl how to generate files with the correct offsets for both 32-bit and 64-bit architectures.
