From 9090f1aa2d91c842aa56fd36023df2f85a32deb4 Mon Sep 17 00:00:00 2001
From: "Pavel @grbit Griaznov" <grbitt@gmail.com>
Date: Tue, 16 Apr 2024 14:09:55 +0200
Subject: [PATCH] undersocre support for numbers (set default base for
 strconv.Parse to 0)

---
 convert.go     |  4 ++--
 parser_test.go | 44 ++++++++++++++++++++++++++------------------
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/convert.go b/convert.go
index ef06d4b..82c0912 100644
--- a/convert.go
+++ b/convert.go
@@ -224,7 +224,7 @@ func convert(val string, retval reflect.Value, options multiTag) error {
 			retval.SetBool(b)
 		}
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		base, err := getBase(options, 10)
+		base, err := getBase(options, 0)
 
 		if err != nil {
 			return err
@@ -238,7 +238,7 @@ func convert(val string, retval reflect.Value, options multiTag) error {
 
 		retval.SetInt(parsed)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		base, err := getBase(options, 10)
+		base, err := getBase(options, 0)
 
 		if err != nil {
 			return err
diff --git a/parser_test.go b/parser_test.go
index 5700bcd..29921b1 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -13,11 +13,13 @@ import (
 )
 
 type defaultOptions struct {
-	Int        int `long:"i"`
-	IntDefault int `long:"id" default:"1"`
+	Int           int `long:"i"`
+	IntDefault    int `long:"id" default:"1"`
+	IntUnderscore int `long:"idu" default:"1_0"`
 
-	Float64        float64 `long:"f"`
-	Float64Default float64 `long:"fd" default:"-3.14"`
+	Float64           float64 `long:"f"`
+	Float64Default    float64 `long:"fd" default:"-3.14"`
+	Float64Underscore float64 `long:"fdu" default:"-3_3.14"`
 
 	NumericFlag bool `short:"3"`
 
@@ -45,11 +47,13 @@ func TestDefaults(t *testing.T) {
 			msg:  "no arguments, expecting default values",
 			args: []string{},
 			expected: defaultOptions{
-				Int:        0,
-				IntDefault: 1,
+				Int:           0,
+				IntDefault:    1,
+				IntUnderscore: 10,
 
-				Float64:        0.0,
-				Float64Default: -3.14,
+				Float64:           0.0,
+				Float64Default:    -3.14,
+				Float64Underscore: -33.14,
 
 				NumericFlag: false,
 
@@ -68,13 +72,15 @@ func TestDefaults(t *testing.T) {
 		},
 		{
 			msg:  "non-zero value arguments, expecting overwritten arguments",
-			args: []string{"--i=3", "--id=3", "--f=-2.71", "--fd=2.71", "-3", "--str=def", "--strd=def", "--t=3ms", "--td=3ms", "--m=c:3", "--md=c:3", "--s=3", "--sd=3"},
+			args: []string{"--i=3", "--id=3", "--idu=3_3", "--f=-2.71", "--fd=2.71", "--fdu=2_2.71", "-3", "--str=def", "--strd=def", "--t=3ms", "--td=3ms", "--m=c:3", "--md=c:3", "--s=3", "--sd=3"},
 			expected: defaultOptions{
-				Int:        3,
-				IntDefault: 3,
+				Int:           3,
+				IntDefault:    3,
+				IntUnderscore: 33,
 
-				Float64:        -2.71,
-				Float64Default: 2.71,
+				Float64:           -2.71,
+				Float64Default:    2.71,
+				Float64Underscore: 22.71,
 
 				NumericFlag: true,
 
@@ -93,13 +99,15 @@ func TestDefaults(t *testing.T) {
 		},
 		{
 			msg:  "zero value arguments, expecting overwritten arguments",
-			args: []string{"--i=0", "--id=0", "--f=0", "--fd=0", "--str", "", "--strd=\"\"", "--t=0ms", "--td=0s", "--m=:0", "--md=:0", "--s=0", "--sd=0"},
+			args: []string{"--i=0", "--id=0", "--idu=0", "--f=0", "--fd=0", "--fdu=0", "--str", "", "--strd=\"\"", "--t=0ms", "--td=0s", "--m=:0", "--md=:0", "--s=0", "--sd=0"},
 			expected: defaultOptions{
-				Int:        0,
-				IntDefault: 0,
+				Int:           0,
+				IntDefault:    0,
+				IntUnderscore: 0,
 
-				Float64:        0,
-				Float64Default: 0,
+				Float64:           0,
+				Float64Default:    0,
+				Float64Underscore: 0,
 
 				String:        "",
 				StringDefault: "",