From b36a38a7bbfe12e1d70d5b23ba226a6ef31f7c58 Mon Sep 17 00:00:00 2001
From: Nathan Baulch <nathan.baulch@gmail.com>
Date: Fri, 30 May 2025 22:05:46 +1000
Subject: [PATCH] Use reflect.Value.IsZero for omitempty checks

---
 marshaler.go      | 50 +----------------------------------------------
 marshaler_test.go | 22 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 49 deletions(-)

diff --git a/marshaler.go b/marshaler.go
index 161acd93..2d3d7808 100644
--- a/marshaler.go
+++ b/marshaler.go
@@ -381,7 +381,7 @@ func isNil(v reflect.Value) bool {
 }
 
 func shouldOmitEmpty(options valueOptions, v reflect.Value) bool {
-	return options.omitempty && isEmptyValue(v)
+	return options.omitempty && v.IsZero()
 }
 
 func (enc *Encoder) encodeKv(b []byte, ctx encoderCtx, options valueOptions, v reflect.Value) ([]byte, error) {
@@ -418,54 +418,6 @@ func (enc *Encoder) commented(commented bool, b []byte) []byte {
 	return b
 }
 
-func isEmptyValue(v reflect.Value) bool {
-	switch v.Kind() {
-	case reflect.Struct:
-		return isEmptyStruct(v)
-	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
-		return v.Len() == 0
-	case reflect.Bool:
-		return !v.Bool()
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return v.Int() == 0
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		return v.Uint() == 0
-	case reflect.Float32, reflect.Float64:
-		return v.Float() == 0
-	case reflect.Interface, reflect.Ptr:
-		return v.IsNil()
-	}
-	return false
-}
-
-func isEmptyStruct(v reflect.Value) bool {
-	// TODO: merge with walkStruct and cache.
-	typ := v.Type()
-	for i := 0; i < typ.NumField(); i++ {
-		fieldType := typ.Field(i)
-
-		// only consider exported fields
-		if fieldType.PkgPath != "" {
-			continue
-		}
-
-		tag := fieldType.Tag.Get("toml")
-
-		// special field name to skip field
-		if tag == "-" {
-			continue
-		}
-
-		f := v.Field(i)
-
-		if !isEmptyValue(f) {
-			return false
-		}
-	}
-
-	return true
-}
-
 const literalQuote = '\''
 
 func (enc *Encoder) encodeString(b []byte, v string, options valueOptions) []byte {
diff --git a/marshaler_test.go b/marshaler_test.go
index 9c069a04..2133b930 100644
--- a/marshaler_test.go
+++ b/marshaler_test.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"math"
 	"math/big"
+	"net/netip"
 	"reflect"
 	"strings"
 	"testing"
@@ -1069,6 +1070,8 @@ func TestEncoderOmitempty(t *testing.T) {
 		Ptr     *string           `toml:",omitempty,multiline"`
 		Iface   interface{}       `toml:",omitempty,multiline"`
 		Struct  struct{}          `toml:",omitempty,multiline"`
+		Time    time.Time         `toml:",omitempty,multiline"`
+		IP      netip.Addr        `toml:",omitempty,multiline"`
 	}
 
 	d := doc{}
@@ -1081,6 +1084,25 @@ func TestEncoderOmitempty(t *testing.T) {
 	assert.Equal(t, expected, string(b))
 }
 
+func TestEncoderOmitemptyComparableStruct(t *testing.T) {
+	type doc struct {
+		Time time.Time  `toml:",omitempty"`
+		IP   netip.Addr `toml:",omitempty"`
+	}
+
+	d := doc{
+		Time: time.Date(2001, 2, 3, 4, 5, 6, 7, time.UTC),
+		IP:   netip.MustParseAddr("192.168.178.35"),
+	}
+
+	b, err := toml.Marshal(d)
+	assert.NoError(t, err)
+
+	expected := "Time = 2001-02-03T04:05:06.000000007Z\nIP = '192.168.178.35'\n"
+
+	assert.Equal(t, expected, string(b))
+}
+
 func TestEncoderTagFieldName(t *testing.T) {
 	type doc struct {
 		String string `toml:"hello"`