[internal-branch.go1.16-vendor] module: allow leading dots in import path elements

These were always disallowed, but the restriction wasn't enforced in
most cases until Go 1.16. That's broken more projects than we hoped.

This change allows leading dots in import path elements. Leading dots
are still not allowed in module path elements. Leading dots were
always allowed in file path elements. Trailing dots are still
forbidden in all cases.

For golang/go#44647

Change-Id: Id9cf728a341931565ab9e81f600b2341aa178683
Reviewed-on: https://go-review.googlesource.com/c/mod/+/297089
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
(cherry picked from commit c8bb1bd8a2aaa5c50fa106c8116850d503792d16)
Reviewed-on: https://go-review.googlesource.com/c/mod/+/298009
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
2 files changed
tree: ae949034564029b75fabc52bceabdbc61381ea7e
  1. LICENSE
  2. PATENTS
  3. README.md
  4. codereview.cfg
  5. go.mod
  6. go.sum
  7. gosumcheck/
  8. internal/
  9. modfile/
  10. module/
  11. semver/
  12. sumdb/
  13. zip/
README.md

mod

PkgGoDev

This repository holds packages for writing tools that work directly with Go module mechanics. That is, it is for direct manipulation of Go modules themselves.

It is NOT about supporting general development tools that need to do things like load packages in module mode. That use case, where modules are incidental rather than the focus, should remain in x/tools, specifically x/tools/go/packages.

The specific case of loading packages should still be done by invoking the go command, which remains the single point of truth for package loading algorithms.