go/packages: fix staticcheck warnings

Ran gopls with staticcheck enabled and found these warnings.

Change-Id: I0b41c0daa19ac98c778d643530c9cb3f5f994399
Reviewed-on: https://go-review.googlesource.com/c/tools/+/201442
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

go/packages/golist.go

@@ -465,6 +465,10 @@ func runNamedQueries(cfg *Config, driver driver, response *responseDeduper, quer
 		}
 
 		files, err := ioutil.ReadDir(modRoot)
+		if err != nil {
+			panic(err) // See above.
+		}
+
 		for _, f := range files {
 			if strings.HasSuffix(f.Name(), ".go") {
 				simpleMatches = append(simpleMatches, rel)
@@ -532,7 +536,7 @@ func runNamedQueries(cfg *Config, driver driver, response *responseDeduper, quer
 		// We're only trying to look at stuff in the module cache, so
 		// disable the network. This should speed things up, and has
 		// prevented errors in at least one case, #28518.
-		tmpCfg.Env = append(append([]string{"GOPROXY=off"}, cfg.Env...))
+		tmpCfg.Env = append([]string{"GOPROXY=off"}, cfg.Env...)
 
 		var err error
 		tmpCfg.Dir, err = ioutil.TempDir("", "gopackages-modquery")
@@ -580,17 +584,29 @@ func roots(cfg *Config) ([]gopathwalk.Root, string, error) {
 
 	var roots []gopathwalk.Root
 	// Always add GOROOT.
-	roots = append(roots, gopathwalk.Root{filepath.Join(goroot, "/src"), gopathwalk.RootGOROOT})
+	roots = append(roots, gopathwalk.Root{
+		Path: filepath.Join(goroot, "/src"),
+		Type: gopathwalk.RootGOROOT,
+	})
 	// If modules are enabled, scan the module dir.
 	if modDir != "" {
-		roots = append(roots, gopathwalk.Root{modDir, gopathwalk.RootCurrentModule})
+		roots = append(roots, gopathwalk.Root{
+			Path: modDir,
+			Type: gopathwalk.RootCurrentModule,
+		})
 	}
 	// Add either GOPATH/src or GOPATH/pkg/mod, depending on module mode.
 	for _, p := range gopath {
 		if modDir != "" {
-			roots = append(roots, gopathwalk.Root{filepath.Join(p, "/pkg/mod"), gopathwalk.RootModuleCache})
+			roots = append(roots, gopathwalk.Root{
+				Path: filepath.Join(p, "/pkg/mod"),
+				Type: gopathwalk.RootModuleCache,
+			})
 		} else {
-			roots = append(roots, gopathwalk.Root{filepath.Join(p, "/src"), gopathwalk.RootGOPATH})
+			roots = append(roots, gopathwalk.Root{
+				Path: filepath.Join(p, "/src"),
+				Type: gopathwalk.RootGOPATH,
+			})
 		}
 	}
 
@@ -983,7 +999,7 @@ func invokeGo(cfg *Config, args ...string) (*bytes.Buffer, error) {
 			//    (the Graphic characters without spaces) and may also exclude the
 			//    characters !"#$%&'()*,:;<=>?[\]^`{|} and the Unicode replacement character U+FFFD.
 			return unicode.IsOneOf([]*unicode.RangeTable{unicode.L, unicode.M, unicode.N, unicode.P, unicode.S}, r) &&
-				strings.IndexRune("!\"#$%&'()*,:;<=>?[\\]^`{|}\uFFFD", r) == -1
+				!strings.ContainsRune("!\"#$%&'()*,:;<=>?[\\]^`{|}\uFFFD", r)
 		}
 		if len(stderr.String()) > 0 && strings.HasPrefix(stderr.String(), "# ") {
 			if strings.HasPrefix(strings.TrimLeftFunc(stderr.String()[len("# "):], isPkgPathRune), "\n") {

go/packages/packages_test.go

@@ -96,7 +96,7 @@ func testLoadImportsGraph(t *testing.T, exporter packagestest.Exporter) {
 	}
 
 	// Check graph topology.
-	graph, all := importGraph(initial)
+	graph, _ := importGraph(initial)
 	wantGraph := `
   container/list
   golang.org/fake/a
@@ -135,7 +135,7 @@ func testLoadImportsGraph(t *testing.T, exporter packagestest.Exporter) {
 	}
 
 	// Check graph topology.
-	graph, all = importGraph(initial)
+	graph, all := importGraph(initial)
 	wantGraph = `
   container/list
   golang.org/fake/a
@@ -227,7 +227,7 @@ func testLoadImportsGraph(t *testing.T, exporter packagestest.Exporter) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		graph, all = importGraph(initial)
+		graph, _ = importGraph(initial)
 		wantGraph = `
 * golang.org/fake/subdir/d
 * golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
@@ -1576,11 +1576,11 @@ func testSizes(t *testing.T, exporter packagestest.Exporter) {
 	}
 }
 
-// TestContains_FallbackSticks ensures that when there are both contains and non-contains queries
+// TestContainsFallbackSticks ensures that when there are both contains and non-contains queries
 // the decision whether to fallback to the pre-1.11 go list sticks across both sets of calls to
 // go list.
-func TestContains_FallbackSticks(t *testing.T) { packagestest.TestAll(t, testContains_FallbackSticks) }
-func testContains_FallbackSticks(t *testing.T, exporter packagestest.Exporter) {
+func TestContainsFallbackSticks(t *testing.T) { packagestest.TestAll(t, testContainsFallbackSticks) }
+func testContainsFallbackSticks(t *testing.T, exporter packagestest.Exporter) {
 	exported := packagestest.Export(t, exporter, []packagestest.Module{{
 		Name: "golang.org/fake",
 		Files: map[string]interface{}{
@@ -2590,7 +2590,7 @@ func constant(p *packages.Package, name string) *types.Const {
 }
 
 func copyAll(srcPath, dstPath string) error {
-	return filepath.Walk(srcPath, func(path string, info os.FileInfo, err error) error {
+	return filepath.Walk(srcPath, func(path string, info os.FileInfo, _ error) error {
 		if info.IsDir() {
 			return nil
 		}

go/packages/packagestest/expect.go

@@ -156,7 +156,7 @@ func (e *Exported) getNotes() error {
 			}
 			l, err := expect.Parse(e.ExpectFileSet, filename, content)
 			if err != nil {
-				return fmt.Errorf("Failed to extract expectations: %v", err)
+				return fmt.Errorf("failed to extract expectations: %v", err)
 			}
 			notes = append(notes, l...)
 		}

go/packages/packagestest/export.go

@@ -240,7 +240,7 @@ func Copy(source string) Writer {
 		if !stat.Mode().IsRegular() {
 			// cannot copy non-regular files (e.g., directories,
 			// symlinks, devices, etc.)
-			return fmt.Errorf("Cannot copy non regular file %s", source)
+			return fmt.Errorf("cannot copy non regular file %s", source)
 		}
 		contents, err := ioutil.ReadFile(source)
 		if err != nil {