Restore 1.16 compatibility (#22)

Author: itzg

.github/workflows/test.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v4
       with:
-        go-version: '1.20'
+        go-version: '1.16'
 
     - name: Test
       run: go test -v ./...

addtional_test.go

@@ -26,7 +26,7 @@ func TestTime(t *testing.T) {
 
 	err = flagset.Parse([]string{"-t", "2016-Dec-13==16:03:02"})
 	require.NoError(t, err)
-	expeted, _ := time.Parse(time.DateTime, "2016-12-13 16:03:02")
+	expeted, _ := time.Parse("2006-01-02 15:04:05", "2016-12-13 16:03:02")
 	assert.Equal(t, expeted, config.T)
 }
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/itzg/go-flagsfiller
 
-go 1.20
+go 1.16
 
 require (
 	github.com/iancoleman/strcase v0.2.0

time.go

@@ -12,8 +12,9 @@ func init() {
 }
 
 // DefaultTimeLayout is the default layout string to parse time, following golang time.Parse() format,
-// could be overriden by struct field tag "layout"
-var DefaultTimeLayout = time.DateTime
+// can be overridden per field by field tag "layout". Default value is "2006-01-02 15:04:05", which is
+// the same as time.DateTime in Go 1.20
+var DefaultTimeLayout = "2006-01-02 15:04:05"
 
 type timeValue struct {
 	t      *time.Time