Regex versioning: build group is compared before prerelease, making timestamp-based build numbers override prerelease ordering

[XiyangDong]

How are you running Renovate?

None

Which platform you running Renovate on?

None

Which version of Renovate are you using?

v43.128.1

Please tell us more about your question or problem

Problem

When using regex versioning with both prerelease and build capture groups, the build
value is compared as part of the release array before prerelease is ever evaluated. This
makes it impossible to correctly order tags that have an optional pre-release phase and
a build timestamp.

Our tag format

We publish container images with this tagging convention:

3.5.0-ea.1-1778760581    (early access 1, build timestamp)
3.5.0-ea.2-1778760744    (early access 2, build timestamp)                                                                                                                                                     
3.5.0-1781820018          (GA release, build timestamp)                                                                                                                                                        

The intended ordering is:

3.5.0-ea.1-... < 3.5.0-ea.2-... < 3.5.0-...

Within the same EA level, the build timestamp should act as a tiebreaker (multiple builds
can be published for the same EA phase).

Our versioning regex

regex:^(?<major>\d+)\.(?<minor>\d+)(?:\.(?<patch>\d+))?(?:-ea\.(?<prerelease>\d+))?-(?<build>\d+)$

What happens

Renovate proposed updating from 3.5.0-ea.2-1778760581 to 3.5.0-ea.1-1780597972 because
the build timestamp 1780597972 > 1778760581. The EA level (ea.1 < ea.2) was ignored.

Parsing the two versions:

Field	3.5.0-ea.2-1778760581	3.5.0-ea.1-1780597972
major	3	3
minor	5	5
patch	0	0
build	1778760581	1780597972
prerelease	"2"	"1"

_compare() in lib/modules/versioning/generic.ts compares the release array
[major, minor, patch, build] left-to-right and returns on the first difference. Since
build is in the array, it is compared before prerelease is ever checked. The comparison
stops at 1780597972 > 1778760581 and declares ea.1 newer. The prerelease comparison
("2" > "1") never runs.

The same problem affects GA vs EA ordering: GA wins only because its build timestamp
happens to be higher. If an EA build ever had a higher timestamp than the GA build, it
would rank above GA — ordering by accident, not by design.

Root cause

In lib/modules/versioning/regex/index.ts, _parse() appends the build capture group
as a numeric element of the release array: [major, minor, patch, build?, revision?].

In lib/modules/versioning/generic.ts, _compare() compares the release array
exhaustively before consulting prerelease. There is no way for a user to change this
order via configuration.

Why existing workarounds don't work

Workaround	Problem
Use compatibility for the build timestamp	Versions with the same EA level but different timestamps become "equal"; Renovate won't propose updates between them. We need the timestamp tiebreaker within an EA phase.
Capture the timestamp inside the prerelease string (e.g. ea.2-1778760581)	localeCompare with numeric: true does not reliably sort mixed alpha-numeric strings like ea.2-1778760581 vs ea.1-1780597972.
Drop the timestamp from the regex entirely	Loses the ability to tiebreak between multiple builds of the same EA phase.
ignoreUnstable: false	Controls filtering, not comparison order.

Proposed fix

The comparison order should be:

[major, minor, patch] → prerelease → build

rather than the current:

[major, minor, patch, build] → prerelease

One approach: introduce a way to mark the build group as a "post-prerelease tiebreaker"
so it is evaluated after prerelease, not before. This could be an opt-in flag in the
regex versioning config (e.g. buildIsPostPrerelease: true) to avoid changing the default
behavior for existing users.

Environment

• Renovate v43.128.1
• Datasource: Docker (quay.io)
• Versioning: regex

References

• lib/modules/versioning/regex/index.ts — _parse(), where build is pushed into the release array
• lib/modules/versioning/generic.ts — _compare(), where the release array is compared before prerelease
• Renovate regex versioning docs: https://docs.renovatebot.com/modules/versioning/regex/

Logs (if relevant)

Logs

Replace this text with your logs, between the starting and ending triple backticks

[andre-motta]

+1 to adding an option to change the ordering. I dont think this should be changed as default.

[viceice]

I disagree, because it would break a lot other use cases, eg 1.2.3.4-beta.1 and 1.2.3.5-beta.2. that would get wrong order.

[andre-motta]

The ask is not to change permanently but instead having it as an optional argument to change the ordering.
I 100% agree this should not change as default behavior.

[XiyangDong]

Is there anyway we can have regex that satisfy

3.5.1-3 > 3.5.0-3 > 3.5.0-2 > 3.5.0-ea.2-3 > 3.5.0-ea.1-4