gopls/internal/lsp/cache: don't scan for modules when defining a view

With zero-config gopls, we no longer need to scan for modules when
defining the default view for a folder. If there is no go.mod or go.work
file in a parent directory, just use an ad-hoc view until the first file
is opened.

Delete tests that were explicitly testing the view narrowing logic, and
so no longer make sense.

For golang/go#57979

Change-Id: Ib2ff96068b2e17d652f24d5ec05e1f2335a7f222
Reviewed-on: https://go-review.googlesource.com/c/tools/+/553096
Reviewed-by: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

gopls/internal/lsp/cache/view.go

@@ -883,22 +883,9 @@ func defineView(ctx context.Context, fs file.Source, folder *Folder, forFile fil
 
 	// When deriving the best view for a given file, we only want to search
 	// up the directory hierarchy for modfiles.
-	//
-	// If forURI is unset, we still use the legacy heuristic of scanning for
-	// nested modules (this will be removed as part of golang/go#57979).
-	if forFile != nil {
-		def.gomod, err = findRootPattern(ctx, dirURI, "go.mod", fs)
-		if err != nil {
-			return nil, err
-		}
-	} else {
-		// filterFunc is the path filter function for this workspace folder. Notably,
-		// it is relative to folder (which is specified by the user), not root.
-		filterFunc := relPathExcludedByFilterFunc(folder.Dir.Path(), folder.Env.GOMODCACHE, folder.Options.DirectoryFilters)
-		def.gomod, err = findWorkspaceModFile(ctx, folder.Dir, fs, filterFunc)
-		if err != nil {
-			return nil, err
-		}
+	def.gomod, err = findRootPattern(ctx, dirURI, "go.mod", fs)
+	if err != nil {
+		return nil, err
 	}
 
 	// Determine how we load and where to load package information for this view
@@ -1345,18 +1332,6 @@ func allFilesExcluded(files []string, filterFunc func(protocol.DocumentURI) bool
 	return true
 }
 
-// relPathExcludedByFilterFunc returns a func that filters paths relative to the
-// given folder according the given GOMODCACHE value and directory filters (see
-// settings.BuildOptions.DirectoryFilters).
-//
-// The resulting func returns true if the directory should be skipped.
-func relPathExcludedByFilterFunc(folder, gomodcache string, directoryFilters []string) func(string) bool {
-	filterer := buildFilterer(folder, gomodcache, directoryFilters)
-	return func(path string) bool {
-		return relPathExcludedByFilter(path, filterer)
-	}
-}
-
 func relPathExcludedByFilter(path string, filterer *Filterer) bool {
 	path = strings.TrimPrefix(filepath.ToSlash(path), "/")
 	return filterer.Disallow(path)

gopls/internal/test/integration/modfile/modfile_test.go

@@ -11,8 +11,8 @@ import (
 	"testing"
 
 	"golang.org/x/tools/gopls/internal/hooks"
-	. "golang.org/x/tools/gopls/internal/test/integration"
 	"golang.org/x/tools/gopls/internal/test/compare"
+	. "golang.org/x/tools/gopls/internal/test/integration"
 	"golang.org/x/tools/gopls/internal/util/bug"
 
 	"golang.org/x/tools/gopls/internal/lsp/protocol"
@@ -427,8 +427,9 @@ func main() {
 		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
 		{"nested", WithOptions(ProxyFiles(proxy))},
 	}.Run(t, mod, func(t *testing.T, env *Env) {
-		env.OnceMet(
-			InitialWorkspaceLoad,
+		// With zero-config gopls, we must open a/main.go to have a View including a/go.mod.
+		env.OpenFile("a/main.go")
+		env.AfterChange(
 			Diagnostics(env.AtRegexp("a/go.mod", "require")),
 		)
 		env.RunGoCommandInDir("a", "mod", "tidy")

gopls/internal/test/integration/workspace/directoryfilters_test.go

@@ -90,54 +90,6 @@ const X = 1
 	})
 }
 
-func TestDirectoryFiltersWorkspaceModules(t *testing.T) {
-	// Define a module include.com which should be in the workspace, plus a
-	// module exclude.com which should be excluded and therefore come from
-	// the proxy.
-	const files = `
--- include/go.mod --
-module include.com
-
-go 1.12
-
-require exclude.com v1.0.0
-
--- include/go.sum --
-exclude.com v1.0.0 h1:Q5QSfDXY5qyNCBeUiWovUGqcLCRZKoTs9XdBeVz+w1I=
-exclude.com v1.0.0/go.mod h1:hFox2uDlNB2s2Jfd9tHlQVfgqUiLVTmh6ZKat4cvnj4=
-
--- include/include.go --
-package include
-
-import "exclude.com"
-
-var _ = exclude.X // satisfied only by the workspace version
--- exclude/go.mod --
-module exclude.com
-
-go 1.12
--- exclude/exclude.go --
-package exclude
-
-const X = 1
-`
-	const proxy = `
--- exclude.com@v1.0.0/go.mod --
-module exclude.com
-
-go 1.12
--- exclude.com@v1.0.0/exclude.go --
-package exclude
-`
-	WithOptions(
-		Modes(Experimental),
-		ProxyFiles(proxy),
-		Settings{"directoryFilters": []string{"-exclude"}},
-	).Run(t, files, func(t *testing.T, env *Env) {
-		env.Await(Diagnostics(env.AtRegexp("include/include.go", `exclude.(X)`)))
-	})
-}
-
 // Test for golang/go#46438: support for '**' in directory filters.
 func TestDirectoryFilters_Wildcard(t *testing.T) {
 	filters := []string{"-**/bye"}

gopls/internal/test/integration/workspace/workspace_test.go

@@ -7,7 +7,6 @@ package workspace
 import (
 	"context"
 	"fmt"
-	"path/filepath"
 	"strings"
 	"testing"
 
@@ -975,43 +974,6 @@ func main() {
 	})
 }
 
-// Sometimes users may have their module cache within the workspace.
-// We shouldn't consider any module in the module cache to be in the workspace.
-func TestGOMODCACHEInWorkspace(t *testing.T) {
-	const mod = `
--- a/go.mod --
-module a.com
-
-go 1.12
--- a/a.go --
-package a
-
-func _() {}
--- a/c/c.go --
-package c
--- gopath/src/b/b.go --
-package b
--- gopath/pkg/mod/example.com/go.mod --
-module example.com
-
-go 1.12
--- gopath/pkg/mod/example.com/main.go --
-package main
-`
-	WithOptions(
-		EnvVars{"GOPATH": filepath.FromSlash("$SANDBOX_WORKDIR/gopath")},
-		Modes(Default),
-	).Run(t, mod, func(t *testing.T, env *Env) {
-		// Because logs are asynchronous, this test can't use OnceMet.
-		env.Await(
-			// Confirm that the build configuration is seen as valid,
-			// even though there are technically multiple go.mod files in the
-			// worskpace.
-			LogMatching(protocol.Info, ".*view type GoModView.*", 1, false),
-		)
-	})
-}
-
 // Tests the fix for golang/go#52500.
 func TestChangeTestVariant_Issue52500(t *testing.T) {
 	const src = `