New protoc versioning breaks configure

[peternewman]

checking for protoc... /usr/local/bin/protoc
+ test -z /usr/local/bin/protoc
+ test -n 2.3.0
+ printf '%s\n' 'configure:25925: checking protoc version'
+ printf %s 'checking protoc version... '
++ /usr/local/bin/protoc --version
++ grep libprotoc
++ sed 's/.*\([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\).*/\1/g'
+ protoc_version='libprotoc 23.3'
+ required=2.3.0
++ echo 2.3.0
++ sed 's/[^0-9].*//'
+ required_major=2
++ echo 2.3.0
++ sed 's/[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*/\1/'
+ required_minor=3
++ echo 2.3.0
++ sed 's/^.*[^0-9]//'
+ required_patch=0
++ echo libprotoc 23.3
++ sed 's/[^0-9].*//'
+ actual_major=
++ echo libprotoc 23.3
++ sed 's/[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*/\1/'
+ actual_minor='libprotoc 23.3'
++ echo libprotoc 23.3
++ sed 's/^.*[^0-9]//'
+ actual_patch=3
++ expr '>' 2 '|' = 2 '&' libprotoc 23.3 '>' 3 '|' = 2 '&' libprotoc 23.3 = 3 '&' 3 '>=' 0
expr: syntax error
+ protoc_version_proper=
+ test '' = 1
+ as_fn_error 1 'protoc version too old libprotoc 23.3 < 2.3.0' 25948 5
+ as_status=1
+ test 1 -eq 0
+ test 5
+ as_lineno=25948
+ as_lineno_stack=as_lineno_stack=
+ printf '%s\n' 'configure:25948: error: protoc version too old libprotoc 23.3 < 2.3.0'
+ printf '%s\n' 'configure: error: protoc version too old libprotoc 23.3 < 2.3.0'
configure: error: protoc version too old libprotoc 23.3 < 2.3.0

See https://github.com/OpenLightingProject/ola/actions/runs/5341378456/jobs/9682134019

https://protobuf.dev/support/version-support/

[yardenac]

Is this version check even still necessary? 2.3.0 and 2.4.0 are both over 12 years old.

Checking against both the old and new version schemes would lead to some unwieldy spaghetti logic, so it might be best to just get rid of the check.

[yardenac]

Current check happens at https://github.com/OpenLightingProject/ola/blob/master/config/ola.m4#L50 and is called from https://github.com/OpenLightingProject/ola/blob/master/configure.ac#L851 - as you can see, the current code assumes a three-part version, while newer protoc returns a two-part one.

[peternewman]

Is this version check even still necessary? 2.3.0 and 2.4.0 are both over 12 years old.

Checking against both the old and new version schemes would lead to some unwieldy spaghetti logic, so it might be best to just get rid of the check.

While there may be vanishingly few people running that old version, given they've just done something as out there as breaking away from semver, there's no guarantee we won't need to support further special edge cases in future unfortunately.

I didn't think it would be too hard to fix or workaround, and indeed it wasn't, a bit of poking of the sed massaging before the version check has resulted in this code which seems to work on both new and old versions:
#1875

Clearly there are other issues with my mac build, but I should be able to just cherry-pick that into a new branch to get it merged in.

[SpotlightKid]

Additionally. unfortunately, protobuf also requires at least C++14 but the configure only set -std=gnu++11, making the compilation of the test programs, which check for the protobuf headers, fail.

(This is after applying the fix for the protobuf version check in #1875.)

configure:25968: checking for google/protobuf/compiler/command_line_interface.h
configure:25968: g++ -c -g -O2 -std=gnu++11   conftest.cpp >&5
In file included from /usr/include/absl/base/config.h:86,
                 from /usr/include/absl/base/attributes.h:37,
                 from /usr/include/absl/base/internal/raw_logging.h:24,
                 from /usr/include/absl/container/internal/btree.h:61,
                 from /usr/include/absl/container/btree_map.h:56,
                 from /usr/include/google/protobuf/compiler/command_line_interface.h:48,
                 from conftest.cpp:178:
/usr/include/absl/base/policy_checks.h:79:2: error: #error "C++ versions less than C++14 are not supported."
   79 | #error "C++ versions less than C++14 are not supported."
      |  ^~~~~

[peternewman]

This says that protobuf supported C++11 until just before version 22.0:
https://protobuf.dev/news/2022-08-03/
Likewise this release of Abseil should work with C++11:
https://github.com/abseil/abseil-cpp/tree/20220623.1