Proposal: TINYGOTOOLCHAIN - Toolchain version management for TinyGo

[sivchari]

Summary

Add Go 1.21-style toolchain version management to TinyGo, enabling reproducible builds by specifying the required TinyGo version.

Motivation

The motivation that I propose is to reproducible builds. I sometime want to ensure the same TinyGo version is used across different machines.

Proposed Design

We add new env value like TINYGOTOOLCHAIN following the GOTOOLCHAIN.
The usage is like this

# Use specific version (auto-download if not cached)
TINYGOTOOLCHAIN=tinygo0.40.1 tinygo build

# Use only system-installed TinyGo
TINYGOTOOLCHAIN=local tinygo build

If the specific version is not cached, it automatically downloads the version from GitHub releases. I don't determine the destination where TinyGo which installed via TINYGOTOOLCHAIN yet, so would like to discuss it.

If it make sense to you, I'd like to implement this feature. What do you think ?

[eliasnaur]

Why not the other way around? That is, making TinyGo work as a GOTOOLCHAIN, similar to what Embedded Go did.

[sivchari]

Thanks for the pointer! I tried implementing this pattern and it works well.

Prototype: https://github.com/sivchari/tinygo-dl

go install github.com/sivchari/tinygo-dl/tinygo0.40.1@latest
tinygo0.40.1 download
tinygo0.40.1 version
# tinygo version 0.40.1 darwin/arm64

This is simpler than adding a new TINYGOTOOLCHAIN environment variable. If TinyGo officially supports this pattern (e.g., github.com/tinygo-org/dl), it sounds great.

[eliasnaur]

Does GOTOOLCHAIN=tinygo go build <program> build a program with TinyGo? That's the bigger part of the work.

[sivchari]

I've investigated.

$ GOTOOLCHAIN=tinygo go build ./...
go: invalid GOTOOLCHAIN "tinygo"

Go requires toolchain names to start with go1 or contain -go1 (see https://github.com/golang/go/blob/master/src/cmd/go/internal/toolchain/select.go#L283-L285).

So what about renaming tinygo to go1.XX-tinygo ? It also happened failure. Since when Go switches toolchains, it sets GOTOOLCHAIN_INTERNAL_SWITCH_VERSION and expects the target binary to be that Go version. TinyGo internally calls go env, which invokes the system Go. That Go sees the env var and fails because its version doesn't match go1.25-tinygo.

Please let me know if I've misunderstood anything.

[eliasnaur]

There's no misunderstanding, making TinyGo work with as a GOTOOLCHAIN is a big change.

[sivchari]

Hello, @deadprogram
What are your thoughts on this proposal? While the title mentions TINYGOTOOLCHAIN, I believe the dl pattern is the better choice. Since adopting this approach requires creating a repository, I'd like to discuss how to proceed. I'll also change the issue title once the policy is finalized.