Support :all syntax correctly when embedding

test/embed/BUILD

@@ -3,13 +3,13 @@ subinclude("//build_defs:go")
 go_library(
     name = "embed",
     srcs = ["embed.go"],
-    resources = ["hello.txt"],
+    resources = ["hello.txt", "subdir"],
 )
 
 go_test(
     name = "embed_test",
     srcs = ["embed_test.go"],
-    resources = ["hello.txt"],
+    resources = ["hello.txt", "subdir"],
     deps = [
         ":embed",
         "//third_party/go:testify",

test/embed/embed.go

@@ -1,6 +1,12 @@
 package embed
 
-import _ "embed"
+import "embed"
 
 //go:embed hello.txt
 var hello string
+
+//go:embed subdir
+var subdir embed.FS
+
+//go:embed all:subdir
+var subdirAll embed.FS

test/embed/embed_test.go

@@ -10,3 +10,14 @@ import (
 func TestLibEmbed(t *testing.T) {
 	assert.Equal(t, "hello", strings.TrimSpace(hello))
 }
+
+func TestEmbedDir(t *testing.T) {
+	_, err := subdir.ReadFile("subdir/_test.txt")
+	assert.Error(t, err)
+}
+
+func TestEmbedDirAll(t *testing.T) {
+	b, err := subdirAll.ReadFile("subdir/_test.txt")
+	assert.NoError(t, err)
+	assert.Equal(t, "hello", strings.TrimSpace(string(b)))
+}

test/embed/subdir/_test.txt

@@ -0,0 +1 @@
+hello

tools/please_go/embed/embed.go

@@ -7,6 +7,7 @@ import (
 	"go/build"
 	"io"
 	"io/fs"
+	"log"
 	"path"
 	"path/filepath"
 	"strings"
@@ -54,6 +55,7 @@ func Parse(gofiles []string) (*Cfg, error) {
 // AddPackage parses a go package and adds any embed patterns to the configuration
 func (cfg *Cfg) AddPackage(pkg *build.Package) error {
 	for _, pattern := range append(append(pkg.EmbedPatterns, pkg.TestEmbedPatterns...), pkg.XTestEmbedPatterns...) {
+		log.Printf("here %s", pattern)
 		paths, err := relglob(pkg.Dir, pattern)
 		if err != nil {
 			return err
@@ -79,6 +81,13 @@ func dirs(files []string) []string {
 }
 
 func relglob(dir, pattern string) ([]string, error) {
+	// Go allows prefixing the pattern with all: which picks up files prefixed with . or _ (by default these should be ignored)
+	includeHidden := false
+	if strings.HasPrefix(pattern, "all:") {
+		pattern = strings.TrimPrefix(pattern, "all:")
+		includeHidden = true
+	}
+
 	paths, err := filepath.Glob(path.Join(dir, pattern))
 	if err == nil && len(paths) == 0 {
 		return nil, fmt.Errorf("pattern %s: no matching paths found", pattern)
@@ -89,7 +98,9 @@ func relglob(dir, pattern string) ([]string, error) {
 			if err != nil {
 				return err
 			} else if !d.IsDir() {
-				ret = append(ret, strings.TrimLeft(strings.TrimPrefix(path, dir), string(filepath.Separator)))
+				if hidden := strings.HasPrefix(d.Name(), ".") || strings.HasPrefix(d.Name(), "_"); !hidden || includeHidden {
+					ret = append(ret, strings.TrimLeft(strings.TrimPrefix(path, dir), string(filepath.Separator)))
+				}
 			}
 			return nil
 		}); err != nil {