From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 21 Apr 2026 14:58:00 +0000 (-0400)
Subject: Remove gen_node_support.pl's ad-hoc ABI stability check.
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=1cd3cd372ae497f3134126edc96aa56352e7f4a0;p=thirdparty%2Fpostgresql.git

Remove gen_node_support.pl's ad-hoc ABI stability check.

We installed this in commit eea9fa9b2 to protect against foreseeable
mistakes that would break ABI in stable branches by renumbering
NodeTag enum entries.  However, we now have much more thorough
ABI stability checks thanks to buildfarm members using libabigail
(see the .abi-compliance-history mechanism).  So this incomplete,
single-purpose check seems like an anachronism.  I wouldn't object
to keeping it were it not that it requires an additional manual step
when making a new stable git branch.  That seems like something easy
to screw up, so let's get rid of it.

This patch just removes the logic that checks for changes in the last
auto-assigned NodeTag value.  We still need eea9fa9b2's cross-check
on the supplied list of header files, to prevent divergence between
the makefile and meson build systems.  We'll also sometimes need the
nodetag_number() infrastructure for hand-assigning new NodeTags in
stable branches.

Discussion: https://postgr.es/m/1458883.1776143073@sss.pgh.pa.us
---

diff --git a/src/backend/nodes/gen_node_support.pl b/src/backend/nodes/gen_node_support.pl
index a21f5a754bf..f4b1317e99f 100644
--- a/src/backend/nodes/gen_node_support.pl
+++ b/src/backend/nodes/gen_node_support.pl
@@ -96,20 +96,6 @@ my @nodetag_only_files = qw(
   nodes/supportnodes.h
 );
 
-# ARM ABI STABILITY CHECK HERE:
-#
-# In stable branches, set $last_nodetag to the name of the last node type
-# that should receive an auto-generated nodetag number, and $last_nodetag_no
-# to its number.  (Find these values in the last line of the current
-# nodetags.h file.)  The script will then complain if those values don't
-# match reality, providing a cross-check that we haven't broken ABI by
-# adding or removing nodetags.
-# In HEAD, these variables should be left undef, since we don't promise
-# ABI stability during development.
-
-my $last_nodetag = undef;
-my $last_nodetag_no = undef;
-
 # output file names
 my @output_files;
 
@@ -615,30 +601,21 @@ open my $nt, '>', "$output_path/nodetags.h$tmpext"
 printf $nt $header_comment, 'nodetags.h';
 
 my $tagno = 0;
-my $last_tag = undef;
 foreach my $n (@node_types, @extra_tags)
 {
 	next if elem $n, @abstract_types;
 	if (defined $manual_nodetag_number{$n})
 	{
-		# do not change $tagno or $last_tag
+		# do not change $tagno
 		print $nt "\tT_${n} = $manual_nodetag_number{$n},\n";
 	}
 	else
 	{
 		$tagno++;
-		$last_tag = $n;
 		print $nt "\tT_${n} = $tagno,\n";
 	}
 }
 
-# verify that last auto-assigned nodetag stays stable
-die "ABI stability break: last nodetag is $last_tag not $last_nodetag\n"
-  if (defined $last_nodetag && $last_nodetag ne $last_tag);
-die
-  "ABI stability break: last nodetag number is $tagno not $last_nodetag_no\n"
-  if (defined $last_nodetag_no && $last_nodetag_no != $tagno);
-
 close $nt;
 
 
diff --git a/src/tools/RELEASE_CHANGES b/src/tools/RELEASE_CHANGES
index f0d005a6141..653318fd770 100644
--- a/src/tools/RELEASE_CHANGES
+++ b/src/tools/RELEASE_CHANGES
@@ -118,10 +118,6 @@ Starting a New Development Cycle
 * In the newly-made branch, replace "devel" with the branch's major version
   number in the URLs appearing in the top-level README and Makefile files.
 
-* In the newly-made branch, change src/backend/nodes/gen_node_support.pl
-  to enforce ABI stability of the NodeTag list (see "ARM ABI STABILITY
-  CHECK HERE" therein).
-
 * Notify the private committers email list, to ensure all committers
   are aware of the new branch even if they're not paying close attention
   to pgsql-hackers.