pkg/edit: Fix crash in edit:complete-filename when given no arguments.

This fixes #1799.

pkg/edit/complete/generators.go

@@ -22,6 +22,9 @@ var eachExternal = fsutil.EachExternal
 // GenerateFileNames returns filename candidates that are suitable for completing
 // the last argument. It can be used in Config.ArgGenerator.
 func GenerateFileNames(args []string) ([]RawItem, error) {
+	if len(args) == 0 {
+		return nil, nil
+	}
 	return generateFileNames(args[len(args)-1], false)
 }
 

pkg/edit/completion_test.elvts

@@ -1,9 +1,16 @@
-//each:complex-candidate-in-global
+/////////////////////
+# complete-filename #
+/////////////////////
+//complete-filename-in-global
+// Don't crash with no argument. Regression test for b.elv.sh/1799.
+~> complete-filename
 
 /////////////////////
 # complex-candidate #
 /////////////////////
 
+//each:complex-candidate-in-global
+
 ## construction ##
 ~> complex-candidate a/b
 ▶ (edit:complex-candidate a/b &code-suffix='' &display=[^styled])

pkg/edit/transcripts_test.go

@@ -4,6 +4,7 @@ import (
 	"embed"
 	"testing"
 
+	"src.elv.sh/pkg/edit/complete"
 	"src.elv.sh/pkg/eval"
 	"src.elv.sh/pkg/eval/evaltest"
 )
@@ -21,6 +22,8 @@ func TestTranscripts(t *testing.T) {
 		"binding-map-in-global", fnInGlobal("binding-map", makeBindingMap),
 		"wordify-in-global", fnInGlobal("wordify", wordify),
 		"complete-getopt-in-global", fnInGlobal("complete-getopt", completeGetopt),
+		"complete-filename-in-global", fnInGlobal("complete-filename",
+			wrapArgGenerator(complete.GenerateFileNames)),
 		"complex-candidate-in-global", fnInGlobal("complex-candidate", complexCandidate),
 		"add-var-in-global", fnInGlobal("add-var", addVar),
 		"add-vars-in-global", fnInGlobal("add-vars", addVars),