maps: make Clone preserve nil map

The x/exp/maps.Clone function doesn't preserve nil
the way x/exp/slices.Clone does, but it should be.

Fixes golang/go#53817

Change-Id: Ib1867fb6e31d990d8b8a846e9dba8a5b6ba83c48
Reviewed-on: https://go-review.googlesource.com/c/exp/+/417274
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2 files changed
tree: 8161eeb26099458ae8896daf38c5dbca1039f5c0
  1. apidiff/
  2. cmd/
  3. constraints/
  4. devtools/
  5. ebnf/
  6. ebnflint/
  7. errors/
  8. event/
  9. inotify/
  10. io/
  11. jsonrpc2/
  12. maps/
  13. mmap/
  14. rand/
  15. shiny/
  16. shootout/
  17. slices/
  18. sumdb/
  19. typeparams/
  20. utf8string/
  21. .gitattributes
  22. .gitignore
  23. AUTHORS
  24. codereview.cfg
  25. CONTRIBUTING.md
  26. CONTRIBUTORS
  27. go.mod
  28. go.sum
  29. LICENSE
  30. PATENTS
  31. README.md
README.md

exp

PkgGoDev

This subrepository holds experimental and deprecated (in the old directory) packages.

The idea for this subrepository originated as the pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to go get these packages.

Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.

In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)

Caveat emptor.