cmd/go: add minimal support for vgo transition #25069
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Did you just dupe yourself? #24916 |
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Change https://golang.org/cl/109340 mentions this issue: |
bcmills
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NeedsFix
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@gopherbot, please make this a backport candidate for Go 1.9 and 1.10. |
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Backport issue(s) opened: #25139 (for 1.10), #25140 (for 1.9). Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases. |
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There's a bit of a chicken and egg situation with this. The sooner that point releases for Go 1.9 and 1.10 are released with this support, the easier it will be to start adopting vgo. Releasing those then introduces a behavior that must be supported according to https://golang.org/doc/go1compat. If something about the vgo proposal affected by this change is modified, or it is dropped entirely, then we are saddled with unused or incorrect behavior that can't be removed. As far as I am concerned, this support can't be added soon enough. Waiting for a full release of vgo (in Go 1.12) before adding this support would make testing vgo (now and in Go 1.11) in a backwards compatible way impossible. |
What would this achieve? The old "go get" (even "go get -d", "download only") will fail to process a package with |
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By "download code exactly as it has" I mean that it will decide which repositories and which commits to use as before. Once downloaded the interpretation of that code is handled by the logic in "go build" that we will change. |
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Change https://golang.org/cl/114500 mentions this issue: |
…cy operation We want authors to be able to publish code that works with both the current standard go command and the planned new go command support for modules. If authors have tagged their code v2 or later, semantic import versioning means the import paths must include a v2 path element after the path prefix naming the module. One option for making this convention compatible with original go get is to move code into a v2 subdirectory of the root. That makes sense for some authors, but many authors would prefer not to move all the code into a v2 subdirectory for a transition and then move it back up once we everyone has a module-aware go command. Instead, this CL teaches the old (non-module-aware) go command a tiny amount about modules and their import paths, to expand the options for authors who want to publish compatible packages. If an author has a v2 of a package, say my/thing/v2/sub/pkg, in the my/thing repo's sub/pkg subdirectory (no v2 in the file system path), then old go get continues to import that package as my/thing/sub/pkg. But when go get is processing code in any module (code in a tree with a go.mod file) and encounters a path like my/thing/v2/sub/pkg, it will check to see if my/thing/go.mod says "module my/thing/v2". If so, the go command will read the import my/thing/v2/sub/pkg as if it said my/thing/sub/pkg, which is the correct "old" import path for the package in question. This CL will be back-ported to Go 1.10 and Go 1.9 as well. Once users have updated to the latest Go point releases containing this new logic, authors will be able to update to using modules within their own repos, including using semantic import paths with vN path elements, and old go get will still be able to consume those repositories. This CL also makes "go get" ignore meta go-import lines using the new "mod" VCS type. This allows a package to specify both a "mod" type and a "git" type, to present more efficient module access to module-aware go but still present a Git repo to the old "go get". Fixes #24751. Fixes #25069. Backport fixes #25139. Change-Id: I378955613a0d63834d4f50f121f4db7e4d87dc0a Reviewed-on: https://go-review.googlesource.com/114500 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Bryan C. Mills <bcmills@google.com>
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Change https://golang.org/cl/115298 mentions this issue: |
…y operation We want authors to be able to publish code that works with both the current standard go command and the planned new go command support for modules. If authors have tagged their code v2 or later, semantic import versioning means the import paths must include a v2 path element after the path prefix naming the module. One option for making this convention compatible with original go get is to move code into a v2 subdirectory of the root. That makes sense for some authors, but many authors would prefer not to move all the code into a v2 subdirectory for a transition and then move it back up once we everyone has a module-aware go command. Instead, this CL teaches the old (non-module-aware) go command a tiny amount about modules and their import paths, to expand the options for authors who want to publish compatible packages. If an author has a v2 of a package, say my/thing/v2/sub/pkg, in the my/thing repo's sub/pkg subdirectory (no v2 in the file system path), then old go get continues to import that package as my/thing/sub/pkg. But when go get is processing code in any module (code in a tree with a go.mod file) and encounters a path like my/thing/v2/sub/pkg, it will check to see if my/thing/go.mod says "module my/thing/v2". If so, the go command will read the import my/thing/v2/sub/pkg as if it said my/thing/sub/pkg, which is the correct "old" import path for the package in question. This CL will be back-ported to Go 1.10 and Go 1.9 as well. Once users have updated to the latest Go point releases containing this new logic, authors will be able to update to using modules within their own repos, including using semantic import paths with vN path elements, and old go get will still be able to consume those repositories. This CL also makes "go get" ignore meta go-import lines using the new "mod" VCS type. This allows a package to specify both a "mod" type and a "git" type, to present more efficient module access to module-aware go but still present a Git repo to the old "go get". Fixes #24751. Fixes #25069. This backport to Go 1.9 also had to pick up p.Internal.RawImports from CL 74750 and CL 74356 and use it to prepare an updated set of -importmap arguments for the compiler. (The old code only understood vendor-related rewriting of import paths.) Backport fixes #25140. Change-Id: I378955613a0d63834d4f50f121f4db7e4d87dc0a Reviewed-on: https://go-review.googlesource.com/115298 Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Bryan C. Mills <bcmills@google.com> Reviewed-by: Andrew Bonventre <andybons@golang.org>
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I wrote a CLI tool that hopefully helps with this transition in the community: https://github.com/marwan-at-work/mod If you have, or know of, a Go package that is tagged >= 2 but does not use Semantic Import Versioning, feel free to use this tool and let me know if it works/doesn't. I think eventually this should be part of the |
Quoting #24301 (comment):
Define “new” code as code with a go.mod file in the same directory or a parent directory. The old go get must continue to download code exactly as it always has. I propose that the “go build” step adjust its handling of imports in “new” code. Specifically, if an import in new code says x/y/v2/z but x/y/v2/z does not exist and x/y/go.mod says “module x/y/v2”, then go build will read the import as x/y/z instead. We would push this update as a point release for Go 1.9 and Go 1.10.
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