Remove internal string set (#2219)

* remove internal string set

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* incorporate changes from #2227

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* beef up the pkg.License.Merg() doc string

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

internal/file/zip_file_manifest.go

@@ -6,7 +6,8 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/anchore/syft/internal"
+	"github.com/scylladb/go-set/strset"
+
 	"github.com/anchore/syft/internal/log"
 )
 
@@ -40,7 +41,7 @@ func (z ZipFileManifest) Add(entry string, info os.FileInfo) {
 
 // GlobMatch returns the path keys that match the given value(s).
 func (z ZipFileManifest) GlobMatch(patterns ...string) []string {
-	uniqueMatches := internal.NewStringSet()
+	uniqueMatches := strset.New()
 
 	for _, pattern := range patterns {
 		for entry := range z {
@@ -54,7 +55,7 @@ func (z ZipFileManifest) GlobMatch(patterns ...string) []string {
 		}
 	}
 
-	results := uniqueMatches.ToSlice()
+	results := uniqueMatches.List()
 	sort.Strings(results)
 
 	return results

internal/licenses/list.go

@@ -1,20 +1,21 @@
 package licenses
 
-import "github.com/anchore/syft/internal"
-
 // all of these taken from https://github.com/golang/pkgsite/blob/8996ff632abee854aef1b764ca0501f262f8f523/internal/licenses/licenses.go#L338
 // which unfortunately is not exported. But fortunately is under BSD-style license. Take note that this list has
 // been manually updated to include more license filenames (see https://github.com/anchore/syft/pull/2227).
 
-var (
-	FileNames = []string{
+func FileNames() []string {
+	return []string{
+		"AL2.0",
 		"COPYING",
 		"COPYING.md",
 		"COPYING.markdown",
 		"COPYING.txt",
+		"LGPL2.1",
 		"LICENCE",
 		"LICENCE.md",
 		"LICENCE.markdown",
+		"licence.txt",
 		"LICENCE.txt",
 		"LICENSE",
 		"LICENSE.md",
@@ -49,9 +50,5 @@ var (
 		"MIT_LICENCE",
 		"UNLICENSE",
 		"UNLICENCE",
-		"AL2.0",
-		"LGPL2.1",
 	}
-
-	FileNameSet = internal.NewStringSet(FileNames...)
-)
+}