[meta] attrversion.sh: only emit versions for attributes in the checked-out headers - #2363

Fixes #2361

Problem

meta/attrversion.sh collects SAI_METADATA_ATTR_VERSION_* from every vX.Y.Z tag from v1.10.0 up. A clone usually carries all upstream tags, including releases published after the checked-out commit or cut on newer release branches. So the script emitted defines for attributes that do not exist in the checked-out headers, and its output changed whenever a new release was tagged.

For example, v1.17.5 checked out in a clone that has v1.19.1 produces 5,821 defines for the 2,650 attributes in its headers. sonic-sairedis's SWIG binding turns every define into a constant, and the extra ones push pysairedis_wrap.cpp past GCC's max-gcse-memory (-Werror=disabled-optimization). That broke builds of unchanged pinned commits once v1.19.1 was tagged (worked around in sonic-net/sonic-sairedis#2108 and #2109).

Change

The script keeps scanning the same tags, but it now buffers the scan and only prints a define for attributes found in the checked-out headers (committed HEAD or working tree). Every remaining attribute keeps the version of the first tag that contains it, as before.

-        perl -ne '/^(\S+):..\/(\S+)\/\S+.h:\s+(SAI_\w+_ATTR_\w+)/;
-        print "#define SAI_METADATA_ATTR_VERSION_$3 \"$1\" /* $2 */\n" if not defined $h{$3};$h{$3}=1' > $OUTPUT
+        perl -ne '/^(\S+):..\/(\S+)\/\S+.h:\s+(SAI_\w+_ATTR_\w+)/ or next;
+        push @attrs, [$1, $2, $3]; $head{$3} = 1 if $1 eq "HEAD";
+        END { for (@attrs) { my ($ver, $dir, $attr) = @$_;
+            print "#define SAI_METADATA_ATTR_VERSION_$attr \"$ver\" /* $dir */\n" if $head{$attr} and not $h{$attr}++ } }' > $OUTPUT

Why not git tag --merged HEAD (as suggested in #2361)

Point releases are tagged on release branches, and those tags are usually not ancestors of master or of later branches. With --merged HEAD, attributes first released in a point release get the next ancestor tag's version instead. That changes 106 versions on master, 94 on v1.18 and 59 on v1.17. For example, SAI_ACL_TABLE_ATTR_FIELD_NEXT_HOP_USER_META moves from v1.17.1 to v1.18.0. These versions feed sai_attr_metadata_t.apiversion, which syncd compares with the vendor's sai_query_api_version().

Ignoring tags newer than inc/saiversion.h was also considered. It mislabels attributes too, because master's version often lags release-branch point releases: at f60c11f (1.18.0, with v1.18.1 already released) it changes 12 attributes from v1.18.1 to HEAD.

Testing

All tests were run against a full clone with tags up to v1.19.1, comparing the old and new script on the same commit. The v1.19 branch tip is currently the same commit as master, so the master results cover it:

• Full meta make: run as in CI (plain, and with doc/custom-headers copied into custom/) on master/v1.19, v1.18 and v1.17, in a Debian bookworm environment with doxygen 1.9.4 and GCC 12.
  • All generated files, including saimetadata.c, are byte-identical. The only exception is SAI_METADATA_HAVE_ATTR_VERSION in saimetadata.h.
  • No build logs no version defined.
  • On the release branches, make was run with size.sh pointed at HEAD. Its hardcoded origin/master fails the struct-size check there, whichever version of this script is used.
• HEAD label: attributes that are not in any release (the custom-header attributes, a local commit, an uncommitted edit) are still labelled HEAD.
• Removed defines:
  • On master, the 12 removed are for DASH meter attributes (SAI_METER_BUCKET_ATTR_* and related) that Convert DASH meter bucket object to table entry #2056 removed from the headers.
  • On release branches, the others removed are attributes that only exist in later releases.

Notes

• What still depends on the clone's tags: the set of defines now depends only on the checkout. An attribute's version can still change if a release containing it is tagged later. For example, an attribute that is labelled HEAD today, or labelled with a later branch's release, gets the version of the first release that contains it, wherever that release was tagged. That's what the version means. It doesn't change the number of defines.
• Shallow clones and clones without tags: these behave as before.