Toolchain providers

A provider maps a tool name to one Portage package and the executable names the user can shim. It selects only installed package versions. For example, go 1.26 is shorthand for a version-series constraint on dev-lang/go, not a toolchain download.

Included providers

Tool	Gentoo package	Shim commands	Notes
Go	dev-lang/go	go, gofmt	from-file reads go.mod/go.work; sets GOTOOLCHAIN=local
Python	dev-lang/python	python, python3	Uses package-owned python3.13, python3.14, etc.; leaves python-exec system defaults unchanged
Maven	dev-java/maven-bin	mvn	Selects the existing mvn-${SLOT} script; Java runtime selection stays with Gentoo's Java tools

Go versions can only run side by side if the installed ebuilds genuinely permit it. Gentoo already provides separately slotted Python interpreters and Maven versions; no copied Python/Maven ebuilds are required.

eselect version-manager shims install python maven
eselect version-manager list python
eselect version-manager list maven
eselect version-manager set --project python ':3.14'
eselect version-manager set --project maven ':3.10'
python3 --version
mvn --version

An unsatisfied selection fails. system delegates to existing system selectors. Neither Python nor Maven currently implements from-file; it remains an explicit opt-in for Go.

Define a generic provider

Create ~/.config/eselect/version-manager/providers.d/example.conf:

PACKAGE_ATOM="dev-util/example"
COMMANDS="example example-helper"

Then install the shim and select an installed package version:

eselect version-manager shims install example
eselect version-manager set --project example latest

Provider configuration is declarative. Commands must be owned by the selected installed package; a provider cannot invent a binary path or download software.

Providers with the same name follow user-over-system precedence. To replace a built-in provider, set OVERRIDE_BUILTIN="true" explicitly. A command may have only one provider owner; use a provider-name override rather than defining another provider that silently steals a command.

Environment and native requirements

The Go provider sets GOROOT when appropriate and GOTOOLCHAIN=local to avoid implicit downloads. Python relies on a package-owned versioned interpreter; Maven uses its Gentoo-provided versioned script and the existing Java runtime selection.

Custom environment synthesis requires a programmatic provider adapter rather than executable shell code in .eselect.conf. This is a version selector, not an environment-script runner.

The synthetic test providers live in the separate CI fixture overlay. Their fake Go ebuilds are not real toolchain backports.