[dev.cmdgo] cmd/go: remove modload.ModRoot function

In some cases, ModRoot was being called in a multi module context. In
those cases, pass in the correct main module. In other cases, a
mainModule variable was already available, so call MainModules.ModRoot
on that mainModule variable to make it more clear. In yet other cases
ModRoot is just needed to determine GoMod, so determine modroot from
the current directory in those cases.

For #45713

Change-Id: I8c8aa633cfae40d0c8740bdbf985f2b60c9daf2c
Reviewed-on: https://go-review.googlesource.com/c/go/+/339171
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/cmd/go/internal/modload/load.go b/src/cmd/go/internal/modload/load.go
index dd69e2afbf..cb5a2d7a35 100644
--- a/src/cmd/go/internal/modload/load.go
+++ b/src/cmd/go/internal/modload/load.go
@@ -440,7 +440,16 @@ func matchLocalDirs(ctx context.Context, m *search.Match, rs *Requirements) {
 		if !filepath.IsAbs(dir) {
 			absDir = filepath.Join(base.Cwd(), dir)
 		}
-		if search.InDir(absDir, cfg.GOROOTsrc) == "" && search.InDir(absDir, ModRoot()) == "" && pathInModuleCache(ctx, absDir, rs) == "" {
+
+		modRoot := findModuleRoot(absDir)
+		found := false
+		for _, mod := range MainModules.Versions() {
+			if MainModules.ModRoot(mod) == modRoot {
+				found = true
+				break
+			}
+		}
+		if !found && search.InDir(absDir, cfg.GOROOTsrc) == "" && pathInModuleCache(ctx, absDir, rs) == "" {
 			m.Dirs = []string{}
 			m.AddError(fmt.Errorf("directory prefix %s outside available modules", base.ShortPath(absDir)))
 			return
@@ -513,7 +522,7 @@ func resolveLocalPackage(ctx context.Context, dir string, rs *Requirements) (str
 					return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
 				}
 
-				readVendorList()
+				readVendorList(mainModule)
 				pkg := strings.TrimPrefix(suffix, "/vendor/")
 				if _, ok := vendorPkgModule[pkg]; !ok {
 					return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
@@ -582,10 +591,10 @@ func pathInModuleCache(ctx context.Context, dir string, rs *Requirements) string
 	tryMod := func(m module.Version) (string, bool) {
 		var root string
 		var err error
-		if repl, _ := Replacement(m); repl.Path != "" && repl.Version == "" {
+		if repl, replModRoot := Replacement(m); repl.Path != "" && repl.Version == "" {
 			root = repl.Path
 			if !filepath.IsAbs(root) {
-				root = filepath.Join(ModRoot(), root)
+				root = filepath.Join(replModRoot, root)
 			}
 		} else if repl.Path != "" {
 			root, err = modfetch.DownloadDir(repl)