feat(bun): generate native Go array slices for PostgreSQL array columns

Bun's pgdialect scans/appends native slices directly, so array columns
(text[], integer[], uuid[], ...) always generate as plain []string,
[]int32, etc. with an explicit "array" bun tag, regardless of --types
(sqltypes/stdlib/baselib). The SqlXxxArray wrapper types are no longer
used for Bun array columns (gorm is unaffected and keeps using them).

Adds --array-nullable pointer_slice to represent nullable array columns
as *[]T instead of []T, so callers can distinguish SQL NULL (nil) from
'{}' (pointer to an empty slice). Verified end-to-end against a live
PostgreSQL instance for NULL/{}/populated arrays in every --types mode.

Closes #13

vendor/github.com/uptrace/bun/migrate/migrations.go

@@ -0,0 +1,177 @@
+package migrate
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strings"
+)
+
+// MigrationsOption configures a Migrations instance.
+type MigrationsOption func(m *Migrations)
+
+// WithMigrationsDirectory sets the directory where migration files are stored.
+func WithMigrationsDirectory(directory string) MigrationsOption {
+	return func(m *Migrations) {
+		m.explicitDirectory = directory
+	}
+}
+
+// Migrations is a collection of registered migrations.
+type Migrations struct {
+	ms MigrationSlice
+
+	explicitDirectory string
+	implicitDirectory string
+}
+
+// NewMigrations creates a new collection of migrations.
+func NewMigrations(opts ...MigrationsOption) *Migrations {
+	m := new(Migrations)
+	for _, opt := range opts {
+		opt(m)
+	}
+	m.implicitDirectory = filepath.Dir(migrationFile())
+	return m
+}
+
+// Sorted returns a copy of the migrations sorted by name in ascending order.
+func (m *Migrations) Sorted() MigrationSlice {
+	migrations := make(MigrationSlice, len(m.ms))
+	copy(migrations, m.ms)
+	sortAsc(migrations)
+	return migrations
+}
+
+// MustRegister is like Register but panics on error.
+func (m *Migrations) MustRegister(up, down MigrationFunc) {
+	if err := m.Register(up, down); err != nil {
+		panic(err)
+	}
+}
+
+// Register registers up and down migration functions derived from the caller's file name.
+func (m *Migrations) Register(up, down MigrationFunc) error {
+	fpath := migrationFile()
+	name, comment, err := extractMigrationName(fpath)
+	if err != nil {
+		return err
+	}
+
+	m.Add(Migration{
+		Name:    name,
+		Comment: comment,
+		Up:      wrapGoMigrationFunc(up),
+		Down:    wrapGoMigrationFunc(down),
+	})
+
+	return nil
+}
+
+// Add appends a migration to the collection.
+func (m *Migrations) Add(migration Migration) {
+	if migration.Name == "" {
+		panic("migration name is required")
+	}
+	m.ms = append(m.ms, migration)
+}
+
+// DiscoverCaller discovers SQL migration files in the caller's directory.
+func (m *Migrations) DiscoverCaller() error {
+	dir := filepath.Dir(migrationFile())
+	return m.Discover(os.DirFS(dir))
+}
+
+// Discover discovers SQL migration files in the given filesystem.
+func (m *Migrations) Discover(fsys fs.FS) error {
+	return fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+
+		if !strings.HasSuffix(path, ".up.sql") && !strings.HasSuffix(path, ".down.sql") {
+			return nil
+		}
+
+		name, comment, err := extractMigrationName(path)
+		if err != nil {
+			return err
+		}
+
+		migration := m.getOrCreateMigration(name)
+		migration.Comment = comment
+		migrationFunc := newSQLMigrationFunc(fsys, path)
+
+		if strings.HasSuffix(path, ".up.sql") {
+			migration.Up = migrationFunc
+			return nil
+		}
+		if strings.HasSuffix(path, ".down.sql") {
+			migration.Down = migrationFunc
+			return nil
+		}
+
+		return errors.New("migrate: not reached")
+	})
+}
+
+func (m *Migrations) getOrCreateMigration(name string) *Migration {
+	for i := range m.ms {
+		mig := &m.ms[i]
+		if mig.Name == name {
+			return mig
+		}
+	}
+
+	m.ms = append(m.ms, Migration{Name: name})
+	return &m.ms[len(m.ms)-1]
+}
+
+func (m *Migrations) getDirectory() string {
+	if m.explicitDirectory != "" {
+		return m.explicitDirectory
+	}
+	if m.implicitDirectory != "" {
+		return m.implicitDirectory
+	}
+	return filepath.Dir(migrationFile())
+}
+
+func migrationFile() string {
+	const depth = 32
+	var pcs [depth]uintptr
+	n := runtime.Callers(1, pcs[:])
+	frames := runtime.CallersFrames(pcs[:n])
+
+	for {
+		f, ok := frames.Next()
+		if !ok {
+			break
+		}
+		if !strings.Contains(f.Function, "/bun/migrate.") {
+			return f.File
+		}
+	}
+
+	return ""
+}
+
+var fnameRE = regexp.MustCompile(`^(\d{1,14})_([0-9a-z_\-]+)\.`)
+
+func extractMigrationName(fpath string) (string, string, error) {
+	fname := filepath.Base(fpath)
+
+	matches := fnameRE.FindStringSubmatch(fname)
+	if matches == nil {
+		return "", "", fmt.Errorf("migrate: unsupported migration name format: %q", fname)
+	}
+
+	return matches[1], matches[2], nil
+}