Fix: validation now rejects phone codes starting with +0 (#1476)

## Fixes Or Enhances

This PR fixes a bug where the validation incorrectly allowed phone codes
starting with +0.
A unit test has also been added for E.164 validation.

Connected to: #1475

**Make sure that you've checked the boxes below before you submit PR:**
- [x] Tests exist or have been written that cover this particular
change.

@go-playground/validator-maintainers

Author: nodivbyzero

regexes.go

@@ -20,7 +20,7 @@ const (
 	hslRegexString                   = "^hsl\\(\\s*(?:0|[1-9]\\d?|[12]\\d\\d|3[0-5]\\d|360)\\s*,\\s*(?:(?:0|[1-9]\\d?|100)%)\\s*,\\s*(?:(?:0|[1-9]\\d?|100)%)\\s*\\)$"
 	hslaRegexString                  = "^hsla\\(\\s*(?:0|[1-9]\\d?|[12]\\d\\d|3[0-5]\\d|360)\\s*,\\s*(?:(?:0|[1-9]\\d?|100)%)\\s*,\\s*(?:(?:0|[1-9]\\d?|100)%)\\s*,\\s*(?:(?:0.[1-9]*)|[01])\\s*\\)$"
 	emailRegexString                 = "^(?:(?:(?:(?:[a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+(?:\\.([a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+)*)|(?:(?:\\x22)(?:(?:(?:(?:\\x20|\\x09)*(?:\\x0d\\x0a))?(?:\\x20|\\x09)+)?(?:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f]|\\x21|[\\x23-\\x5b]|[\\x5d-\\x7e]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(?:(?:[\\x01-\\x09\\x0b\\x0c\\x0d-\\x7f]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}]))))*(?:(?:(?:\\x20|\\x09)*(?:\\x0d\\x0a))?(\\x20|\\x09)+)?(?:\\x22))))@(?:(?:(?:[a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(?:(?:[a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])(?:[a-zA-Z]|\\d|-|\\.|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*(?:[a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.)+(?:(?:[a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(?:(?:[a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])(?:[a-zA-Z]|\\d|-|\\.|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*(?:[a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.?$"
-	e164RegexString                  = "^\\+[1-9]?[0-9]{7,14}$"
+	e164RegexString                  = "^\\+?[1-9]\\d{1,14}$"
 	base32RegexString                = "^(?:[A-Z2-7]{8})*(?:[A-Z2-7]{2}={6}|[A-Z2-7]{4}={4}|[A-Z2-7]{5}={3}|[A-Z2-7]{7}=|[A-Z2-7]{8})$"
 	base64RegexString                = "^(?:[A-Za-z0-9+\\/]{4})*(?:[A-Za-z0-9+\\/]{2}==|[A-Za-z0-9+\\/]{3}=|[A-Za-z0-9+\\/]{4})$"
 	base64URLRegexString             = "^(?:[A-Za-z0-9-_]{4})*(?:[A-Za-z0-9-_]{2}==|[A-Za-z0-9-_]{3}=|[A-Za-z0-9-_]{4})$"

validator_test.go

@@ -8734,6 +8734,33 @@ func TestRgb(t *testing.T) {
 	AssertError(t, errs, "", "", "", "", "rgb")
 }
 
+func TestE164(t *testing.T) {
+	validate := New()
+
+	s := "+12025550123"
+	errs := validate.Var(s, "e164")
+	Equal(t, errs, nil)
+
+	s = "+447911123456"
+	errs = validate.Var(s, "e164")
+	Equal(t, errs, nil)
+
+	s = "0123456789" // invalid: starts with 0
+	errs = validate.Var(s, "e164")
+	NotEqual(t, errs, nil)
+	AssertError(t, errs, "", "", "", "", "e164")
+
+	s = "++12025550123" // invalid: double +
+	errs = validate.Var(s, "e164")
+	NotEqual(t, errs, nil)
+	AssertError(t, errs, "", "", "", "", "e164")
+
+	s = "+1 202-555-0123" // invalid: contains spaces or dashes
+	errs = validate.Var(s, "e164")
+	NotEqual(t, errs, nil)
+	AssertError(t, errs, "", "", "", "", "e164")
+}
+
 func TestEmail(t *testing.T) {
 	validate := New()