diff --git a/go/packages/golist.go b/go/packages/golist.go
index c581bce..b327a4c 100644
--- a/go/packages/golist.go
+++ b/go/packages/golist.go
@@ -26,7 +26,6 @@
 	"golang.org/x/tools/go/internal/packagesdriver"
 	"golang.org/x/tools/internal/gopathwalk"
 	"golang.org/x/tools/internal/semver"
-	"golang.org/x/tools/internal/span"
 )
 
 // debug controls verbose logging.
@@ -287,42 +286,43 @@
 			return fmt.Errorf("could not determine absolute path of file= query path %q: %v", query, err)
 		}
 		dirResponse, err := driver(cfg, pattern)
-		if err != nil {
+		if err != nil || (len(dirResponse.Packages) == 1 && len(dirResponse.Packages[0].Errors) == 1) {
+			// There was an error loading the package. Try to load the file as an ad-hoc package.
+			// Usually the error will appear in a returned package, but may not if we're in modules mode
+			// and the ad-hoc is located outside a module.
 			var queryErr error
-			if dirResponse, queryErr = adHocPackage(cfg, driver, pattern, query); queryErr != nil {
-				return err // return the original error
+			dirResponse, queryErr = driver(cfg, query)
+			if queryErr != nil {
+				// Return the original error if the attempt to fall back failed.
+				return err
 			}
-		}
-		// `go list` can report errors for files that are not listed as part of a package's GoFiles.
-		// In the case of an invalid Go file, we should assume that it is part of package if only
-		// one package is in the response. The file may have valid contents in an overlay.
-		if len(dirResponse.Packages) == 1 {
-			pkg := dirResponse.Packages[0]
-			for i, err := range pkg.Errors {
-				s := errorSpan(err)
-				if !s.IsValid() {
-					break
-				}
-				if len(pkg.CompiledGoFiles) == 0 {
-					break
-				}
-				dir := filepath.Dir(pkg.CompiledGoFiles[0])
-				filename := filepath.Join(dir, filepath.Base(s.URI().Filename()))
-				if info, err := os.Stat(filename); err != nil || info.IsDir() {
-					break
-				}
-				if !contains(pkg.CompiledGoFiles, filename) {
-					pkg.CompiledGoFiles = append(pkg.CompiledGoFiles, filename)
-					pkg.GoFiles = append(pkg.GoFiles, filename)
-					pkg.Errors = append(pkg.Errors[:i], pkg.Errors[i+1:]...)
-				}
+			// If we get nothing back from `go list`, try to make this file into its own ad-hoc package.
+			if len(dirResponse.Packages) == 0 && queryErr == nil {
+				dirResponse.Packages = append(dirResponse.Packages, &Package{
+					ID:              "command-line-arguments",
+					PkgPath:         query,
+					GoFiles:         []string{query},
+					CompiledGoFiles: []string{query},
+					Imports:         make(map[string]*Package),
+				})
+				dirResponse.Roots = append(dirResponse.Roots, "command-line-arguments")
 			}
-		}
-		// A final attempt to construct an ad-hoc package.
-		if len(dirResponse.Packages) == 1 && len(dirResponse.Packages[0].Errors) == 1 {
-			var queryErr error
-			if dirResponse, queryErr = adHocPackage(cfg, driver, pattern, query); queryErr != nil {
-				return err // return the original error
+			// Special case to handle issue #33482:
+			// If this is a file= query for ad-hoc packages where the file only exists on an overlay,
+			// and exists outside of a module, add the file in for the package.
+			if len(dirResponse.Packages) == 1 && (dirResponse.Packages[0].ID == "command-line-arguments" ||
+				filepath.ToSlash(dirResponse.Packages[0].PkgPath) == filepath.ToSlash(query)) {
+				if len(dirResponse.Packages[0].GoFiles) == 0 {
+					filename := filepath.Join(pattern, filepath.Base(query)) // avoid recomputing abspath
+					// TODO(matloob): check if the file is outside of a root dir?
+					for path := range cfg.Overlay {
+						if path == filename {
+							dirResponse.Packages[0].Errors = nil
+							dirResponse.Packages[0].GoFiles = []string{path}
+							dirResponse.Packages[0].CompiledGoFiles = []string{path}
+						}
+					}
+				}
 			}
 		}
 		isRoot := make(map[string]bool, len(dirResponse.Roots))
@@ -350,74 +350,6 @@
 	return nil
 }
 
-// adHocPackage attempts to construct an ad-hoc package given a query that failed.
-func adHocPackage(cfg *Config, driver driver, pattern, query string) (*driverResponse, error) {
-	// There was an error loading the package. Try to load the file as an ad-hoc package.
-	// Usually the error will appear in a returned package, but may not if we're in modules mode
-	// and the ad-hoc is located outside a module.
-	dirResponse, err := driver(cfg, query)
-	if err != nil {
-		return nil, err
-	}
-	// If we get nothing back from `go list`, try to make this file into its own ad-hoc package.
-	if len(dirResponse.Packages) == 0 && err == nil {
-		dirResponse.Packages = append(dirResponse.Packages, &Package{
-			ID:              "command-line-arguments",
-			PkgPath:         query,
-			GoFiles:         []string{query},
-			CompiledGoFiles: []string{query},
-			Imports:         make(map[string]*Package),
-		})
-		dirResponse.Roots = append(dirResponse.Roots, "command-line-arguments")
-	}
-	// Special case to handle issue #33482:
-	// If this is a file= query for ad-hoc packages where the file only exists on an overlay,
-	// and exists outside of a module, add the file in for the package.
-	if len(dirResponse.Packages) == 1 && (dirResponse.Packages[0].ID == "command-line-arguments" || dirResponse.Packages[0].PkgPath == filepath.ToSlash(query)) {
-		if len(dirResponse.Packages[0].GoFiles) == 0 {
-			filename := filepath.Join(pattern, filepath.Base(query)) // avoid recomputing abspath
-			// TODO(matloob): check if the file is outside of a root dir?
-			for path := range cfg.Overlay {
-				if path == filename {
-					dirResponse.Packages[0].Errors = nil
-					dirResponse.Packages[0].GoFiles = []string{path}
-					dirResponse.Packages[0].CompiledGoFiles = []string{path}
-				}
-			}
-		}
-	}
-	return dirResponse, nil
-}
-
-func contains(files []string, filename string) bool {
-	for _, f := range files {
-		if f == filename {
-			return true
-		}
-	}
-	return false
-}
-
-// errorSpan attempts to parse a standard `go list` error message
-// by stripping off the trailing error message.
-//
-// It works only on errors whose message is prefixed by colon,
-// followed by a space (": "). For example:
-//
-//   attributes.go:13:1: expected 'package', found 'type'
-//
-func errorSpan(err Error) span.Span {
-	if err.Pos == "" {
-		input := strings.TrimSpace(err.Msg)
-		msgIndex := strings.Index(input, ": ")
-		if msgIndex < 0 {
-			return span.Parse(input)
-		}
-		return span.Parse(input[:msgIndex])
-	}
-	return span.Parse(err.Pos)
-}
-
 // modCacheRegexp splits a path in a module cache into module, module version, and package.
 var modCacheRegexp = regexp.MustCompile(`(.*)@([^/\\]*)(.*)`)
 
diff --git a/go/packages/packages_test.go b/go/packages/packages_test.go
index ff8bcc6..b2b2240 100644
--- a/go/packages/packages_test.go
+++ b/go/packages/packages_test.go
@@ -1099,51 +1099,6 @@
 	}
 }
 
-func TestContainsInOverlays(t *testing.T) { packagestest.TestAll(t, testcontainsInOverlays) }
-func testcontainsInOverlays(t *testing.T, exporter packagestest.Exporter) {
-	// This test checks a specific case where a file is empty on disk.
-	// In this case, `go list` will return the package golang.org/fake/c
-	// with only c.go as a GoFile, with an error message for c2.go.
-	// Since there is only one possible package for c2.go to be a part of,
-	// go/packages will parse the filename out of error and add it to GoFiles and CompiledGoFiles.
-	exported := packagestest.Export(t, exporter, []packagestest.Module{{
-		Name: "golang.org/fake",
-		Files: map[string]interface{}{
-			"c/c.go":  `package c; const C = "c"`,
-			"c/c2.go": ``,
-		}}})
-	defer exported.Cleanup()
-
-	dir := filepath.Dir(exported.File("golang.org/fake", "c/c.go"))
-
-	for _, test := range []struct {
-		overlay map[string][]byte
-		want    string
-	}{
-		{
-			overlay: map[string][]byte{filepath.Join(dir, "c2.go"): []byte(`nonsense`)},
-			want:    "golang.org/fake/c",
-		},
-	} {
-		exported.Config.Overlay = test.overlay
-		exported.Config.Mode = packages.LoadImports
-		exported.Config.Logf = t.Logf
-		for filename := range exported.Config.Overlay {
-			initial, err := packages.Load(exported.Config, "file="+filename)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if len(initial) == 0 {
-				t.Fatalf("no packages for %s", filename)
-			}
-			pkg := initial[0]
-			if pkg.PkgPath != test.want {
-				t.Errorf("got %s, want %s", pkg.PkgPath, test.want)
-			}
-		}
-	}
-}
-
 func TestAdHocPackagesBadImport(t *testing.T) {
 	// This test doesn't use packagestest because we are testing ad-hoc packages,
 	// which are outside of $GOPATH and outside of a module.
@@ -1210,36 +1165,38 @@
 
 	// Make sure that the user's value of GO111MODULE does not affect test results.
 	for _, go111module := range []string{"off", "auto", "on"} {
-		config := &packages.Config{
-			Dir:  tmp,
-			Env:  append(os.Environ(), "GOPACKAGESDRIVER=off", fmt.Sprintf("GO111MODULE=%s", go111module)),
-			Mode: packages.LoadAllSyntax,
-			Overlay: map[string][]byte{
-				filename: content,
-			},
-			Logf: t.Logf,
-		}
-		initial, err := packages.Load(config, fmt.Sprintf("file=%s", filename))
-		if err != nil {
-			t.Fatal(err)
-		}
-		if len(initial) == 0 {
-			t.Fatalf("no packages for %s with GO111MODULE=%s", filename, go111module)
-		}
-		// Check value of a.A.
-		a := initial[0]
-		if a.Errors != nil {
-			t.Fatalf("a: got errors %+v, want no error", err)
-		}
-		aA := constant(a, "A")
-		if aA == nil {
-			t.Errorf("a.A: got nil")
-			return
-		}
-		got := aA.Val().String()
-		if want := "1"; got != want {
-			t.Errorf("a.A: got %s, want %s", got, want)
-		}
+		t.Run("GO111MODULE="+go111module, func(t *testing.T) {
+			config := &packages.Config{
+				Dir:  tmp,
+				Env:  append(os.Environ(), "GOPACKAGESDRIVER=off", fmt.Sprintf("GO111MODULE=%s", go111module)),
+				Mode: packages.LoadAllSyntax,
+				Overlay: map[string][]byte{
+					filename: content,
+				},
+				Logf: t.Logf,
+			}
+			initial, err := packages.Load(config, fmt.Sprintf("file=%s", filename))
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(initial) == 0 {
+				t.Fatalf("no packages for %s", filename)
+			}
+			// Check value of a.A.
+			a := initial[0]
+			if a.Errors != nil {
+				t.Fatalf("a: got errors %+v, want no error", err)
+			}
+			aA := constant(a, "A")
+			if aA == nil {
+				t.Errorf("a.A: got nil")
+				return
+			}
+			got := aA.Val().String()
+			if want := "1"; got != want {
+				t.Errorf("a.A: got %s, want %s", got, want)
+			}
+		})
 	}
 }
 
@@ -2273,14 +2230,10 @@
 	}()
 
 	exported.Config.Mode = packages.NeedImports | packages.NeedFiles
-	exported.Config.Logf = t.Logf
 	pkgs, err := packages.Load(exported.Config, "file="+filename)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(pkgs) == 0 {
-		t.Fatalf("no packages for %s", filename)
-	}
 	if len(pkgs) != 1 && pkgs[0].PkgPath != "command-line-arguments" {
 		t.Fatalf("packages.Load: want [command-line-arguments], got %v", pkgs)
 	}