fix: do not init empty arrays (#321)

Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

Author: caarlos0

env.go

@@ -416,12 +416,14 @@ func doParseSlice(ref reflect.Value, processField processFieldFn, opts Options)
 			}
 		}
 
-		if reflect.Ptr == ref.Kind() {
-			resultPtr := reflect.New(sliceType)
-			resultPtr.Elem().Set(result)
-			result = resultPtr
+		if result.Len() > 0 {
+			if reflect.Ptr == ref.Kind() {
+				resultPtr := reflect.New(sliceType)
+				resultPtr.Elem().Set(result)
+				result = resultPtr
+			}
+			ref.Set(result)
 		}
-		ref.Set(result)
 	}
 
 	return nil

env_test.go

@@ -2125,3 +2125,23 @@ func TestIssue298ErrorNestedFieldRequiredNotSet(t *testing.T) {
 	isErrorWithMessage(t, err, `env: required environment variable "FOO_0_STR" is not set`)
 	isTrue(t, errors.Is(err, EnvVarIsNotSetError{}))
 }
+
+func TestIssue320(t *testing.T) {
+	type Test struct {
+		Str string `env:"STR"`
+		Num int    `env:"NUM"`
+	}
+	type ComplexConfig struct {
+		Foo *[]Test `envPrefix:"FOO_"`
+		Bar []Test  `envPrefix:"BAR"`
+		Baz []Test  `env:",init"`
+	}
+
+	cfg := ComplexConfig{}
+
+	isNoErr(t, Parse(&cfg))
+
+	isEqual(t, cfg.Foo, nil)
+	isEqual(t, cfg.Bar, nil)
+	isEqual(t, cfg.Baz, nil)
+}

go.mod

@@ -2,4 +2,6 @@ module github.com/caarlos0/env/v11
 
 retract v11.0.1 // v11.0.1 accidentally introduced a breaking change regarding the behavior of nil pointers. You can now chose to auto-initialize them by setting the `init` tag option.
 
+retract v11.2.0 // v11.2.0 accidentally introduced a breaking change regarding the behavior of nil slices of complex types.
+
 go 1.18