Version 1.4.0 allowed hyphen "-" to be in environment variable names, after 1.4.0 this resulted in a parsing error which breaks backwards compatibility. Added back in hyphen support in variable names with associated test cases.

fixtures/hyphen.env

@@ -0,0 +1,3 @@
+OPTION_A=abc
+OPTION-B=def
+

godotenv_test.go

@@ -184,6 +184,16 @@ func TestLoadEqualsEnv(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestLoadHyphenEnv(t *testing.T) {
+	envFileName := "fixtures/hyphen.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "abc",
+		"OPTION-B": "def",
+	}
+
+	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
+}
+
 func TestLoadQuotedEnv(t *testing.T) {
 	envFileName := "fixtures/quoted.env"
 	expectedValues := map[string]string{

parser.go

@@ -96,8 +96,8 @@ loop:
 			break loop
 		case '_':
 		default:
-			// variable name should match [A-Za-z0-9_.]
-			if unicode.IsLetter(rchar) || unicode.IsNumber(rchar) || rchar == '.' {
+			// variable name should match [A-Za-z0-9_.-]
+			if unicode.IsLetter(rchar) || unicode.IsNumber(rchar) || rchar == '.' || rchar == '-' {
 				continue
 			}