modfile: fix crash on AddGoStmt in empty File

AddGoStmt uses File.Syntax without checking whether
it is nil or not. This causes crashes when using it on empty files that
have not had their Syntax member initialized to a valid pointer.

This change fixes it by ensuring File.Syntax is a valid pointer before
proceeding.

Fixes golang/go#62457.

Change-Id: Iab02039f79e73d939ca5d3e48b29faa5e0a9a5ec
Reviewed-on: https://go-review.googlesource.com/c/mod/+/570115
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2 files changed
tree: 301b984a960c82ee6d7727433043d8abe657b065
  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.