ign-msgs 8.7.1 failed to build on ubuntu/jammy::amd64

[azeey]

The original build was https://build.osrfoundation.org/job/gz-msgs8-debbuilder/636/. I reran it thinking it was a networking issue, but it failed the same way: https://build.osrfoundation.org/job/gz-msgs8-debbuilder/646/

Error messages:

00:08:06.384 autopkgtest [20:57:49]: test build: [-----------------------
00:08:06.384 In file included from /usr/lib/x86_64-linux-gnu/pkgconfig/../../..//include/ignition/msgs8/ignition/msgs.hh:29,
00:08:06.908                  from igntest.c:3:
00:08:06.908 /usr/lib/x86_64-linux-gnu/pkgconfig/../../..//include/ignition/msgs8/ignition/msgs/Utility.hh:24:10: fatal error: ignition/math/AxisAlignedBox.hh: No such file or directory
00:08:07.314    24 | #include <ignition/math/AxisAlignedBox.hh>
00:08:07.734       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00:08:07.734 compilation terminated.
00:08:07.734 autopkgtest [20:57:49]: test build: -----------------------]
autopkgtest [20:57:49]: test build:  - - - - - - - - - - results - - - - - - - - - -
build                FAIL non-zero exit status 1
autopkgtest [20:57:50]: test build:  - - - - - - - - - - stderr - - - - - - - - - -
In file included from /usr/lib/x86_64-linux-gnu/pkgconfig/../../..//include/ignition/msgs8/ignition/msgs.hh:29,
                 from igntest.c:3:
/usr/lib/x86_64-linux-gnu/pkgconfig/../../..//include/ignition/msgs8/ignition/msgs/Utility.hh:24:10: fatal error: ignition/math/AxisAlignedBox.hh: No such file or directory
   24 | #include <ignition/math/AxisAlignedBox.hh>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
autopkgtest [20:57:50]: @@@@@@@@@@@@@@@@@@@@ summary
build                FAIL non-zero exit status 1

[j-rivero]

Umm this one is nice:

The ign-msgs 8.7.1 debbuilder fails in the autopkgtest (DEP-8 build) stage with ignition/math/AxisAlignedBox.hh: No such file or directory.

The actual root cause — a malformed pkg-config file. The DEP-8 build test compiles a consumer with only: g++ ... pkg-config --cflags --libs ignition-msgs8 so if we compare the pkg-config .pcs files for ignition-msgs8.pc:

8.7.0:  Requires: ignition-cmake2 >= 1.1  protobuf >= 3  ignition-math6
8.7.1:  Requires: ignition-cmake2 >= 1.1  protobuf >=    ignition-math6
                                                      ^^^^^ empty version, dangling ">="

protobuf >= 3 became protobuf >= (empty). pkg-config then parses the next token ignition-math6 as protobuf's version constraint, so ignition-math6 is no longer a required package and its include path is dropped.

The chain of events:

1. ign-cmake2's FindIgnProtobuf.cmake:27 unconditionally emits the pkg-config token: ign_pkg_config_entry(IgnProtobuf "protobuf >= ${IgnProtobuf_FIND_VERSION}") with no guard for an empty version. (The same unguarded line still exists in gz-cmake 3/4/main as FindGzProtobuf.cmake:27.)
2. gz-msgs commit 0c0926c "GzProtobuf: Do not require version 3" (GzProtobuf: Do not require version 3 do support Protobuf 4.23.2 (23.2) #346) (Silvio Traversaro, 2023) removed the VERSION 3 arg from ign_find_package(IgnProtobuf …) to allow protobuf 4+/30 discovery via CONFIG mode. This made IgnProtobuf_FIND_VERSION empty.
3. GzProtobuf: Do not require version 3 do support Protobuf 4.23.2 (23.2) #346 landed after the 8.7.0 tag (2022). 8.7.1 (Feb 2026) is the first Fortress release built with it — which is why a "patch" release regressed.

I'm going to patch the ign-cmake2, release and release bump in gz-msgs to get correct build.