v2: Pass BuildTags in an Options struct

v2/execute.go

@@ -79,7 +79,7 @@ func Execute(nameSystems namer.NameSystems, defaultSystem string, getTargets fun
 		buildTags = append(buildTags, buildTag)
 	}
 
-	p := parser.New(buildTags)
+	p := parser.NewWithOptions(parser.Options{BuildTags: buildTags})
 	if err := p.LoadPackages(patterns...); err != nil {
 		return fmt.Errorf("failed making a parser: %v", err)
 	}

v2/generator/snippet_writer_test.go

@@ -27,7 +27,7 @@ import (
 )
 
 func construct(t *testing.T, patterns ...string) *generator.Context {
-	b := parser.New(nil)
+	b := parser.New()
 
 	if err := b.LoadPackages(patterns...); err != nil {
 		t.Fatalf("unexpected error: %v", err)

v2/parser/parse.go

@@ -67,18 +67,29 @@ type fileLine struct {
 	line int
 }
 
-// New constructs a new builder.
-func New(buildTags []string) *Parser {
+// New constructs a new Parser.
+func New() *Parser {
+	return NewWithOptions(Options{})
+}
+
+func NewWithOptions(opts Options) *Parser {
 	return &Parser{
 		goPkgs:                map[string]*packages.Package{},
 		userRequested:         map[string]bool{},
 		fullyProcessed:        map[string]bool{},
 		fset:                  token.NewFileSet(),
 		endLineToCommentGroup: map[fileLine]*ast.CommentGroup{},
-		buildTags:             buildTags,
+		buildTags:             opts.BuildTags,
 	}
 }
 
+// Options holds optional settings for the Parser.
+type Options struct {
+	// BuildTags is a list of optional tags to be specified when loading
+	// packages.
+	BuildTags []string
+}
+
 // FindPackages expands the provided patterns into a list of Go import-paths,
 // much like `go list -find`.
 func (p *Parser) FindPackages(patterns ...string) ([]string, error) {

v2/parser/parse_test.go

@@ -28,7 +28,7 @@ import (
 )
 
 func TestNew(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 	if parser.goPkgs == nil {
 		t.Errorf("expected .goPkgs to be initialized")
 	}
@@ -123,22 +123,22 @@ func keys[T any](m map[string]T) []string {
 func TestAddBuildTags(t *testing.T) {
 	testTags := []string{"foo", "bar", "qux"}
 
-	parser := New(nil)
+	parser := New()
 	if len(parser.buildTags) != 0 {
 		t.Errorf("expected no default build tags, got %v", parser.buildTags)
 	}
-	parser = New(testTags[0:1])
+	parser = NewWithOptions(Options{BuildTags: testTags[0:1]})
 	if want, got := testTags[0:1], parser.buildTags; !sliceEq(want, got) {
 		t.Errorf("wrong build tags:\nwant: %v\ngot:  %v", pretty(want), pretty(got))
 	}
-	parser = New(testTags)
+	parser = NewWithOptions(Options{BuildTags: testTags})
 	if want, got := testTags, parser.buildTags; !sliceEq(want, got) {
 		t.Errorf("wrong build tags:\nwant: %v\ngot:  %v", pretty(want), pretty(got))
 	}
 }
 
 func TestFindPackages(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 
 	// Proper packages with deps.
 	if pkgs, err := parser.FindPackages("./testdata/root1", "./testdata/root2", "./testdata/roots345/..."); err != nil {
@@ -194,7 +194,7 @@ func TestAlreadyLoaded(t *testing.T) {
 		}
 	}
 
-	parser := New(nil)
+	parser := New()
 
 	// Test loading something we don't have.
 	if existing, netNew, err := parser.alreadyLoaded("./testdata/root1"); err != nil {
@@ -243,7 +243,7 @@ func TestAlreadyLoaded(t *testing.T) {
 }
 
 func TestLoadPackagesInternal(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 
 	// Proper packages with deps.
 	if pkgs, err := parser.loadPackages("./testdata/root1", "./testdata/root2", "./testdata/roots345/..."); err != nil {
@@ -339,7 +339,7 @@ func TestLoadPackagesInternal(t *testing.T) {
 }
 
 func TestLoadPackagesTo(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 	u := types.Universe{}
 
 	// Proper packages with deps.
@@ -444,7 +444,7 @@ func TestForEachPackageRecursive(t *testing.T) {
 }
 
 func TestUserRequestedPackages(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 
 	// Proper packages with deps.
 	if err := parser.LoadPackages("./testdata/root1", "./testdata/root2", "./testdata/roots345/..."); err != nil {
@@ -469,7 +469,7 @@ func TestUserRequestedPackages(t *testing.T) {
 }
 
 func TestAddOnePkgToUniverse(t *testing.T) {
-	parser := New(nil)
+	parser := New()
 
 	// Proper packages with deps.
 	if pkgs, err := parser.loadPackages("./testdata/root2"); err != nil {