modfile: Add support for tool lines

Add new tool directive to go.mod parser and functions
to add and drop them.

For golang/go#48429

Change-Id: I37667a69ded9d59ea248ec48ad35c87592103218
Reviewed-on: https://go-review.googlesource.com/c/mod/+/508355
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
3 files changed
tree: d0ccf8c7c7c5df9e78766044e5147f50555a24cb
  1. gosumcheck/
  2. internal/
  3. modfile/
  4. module/
  5. semver/
  6. sumdb/
  7. zip/
  8. codereview.cfg
  9. go.mod
  10. go.sum
  11. LICENSE
  12. PATENTS
  13. README.md
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.